OEO102040 LTE ERAN2.1 Scheduling Feature ISSUE 1.01

LTE eRAN2.1 Scheduling Feature

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LTE eRAN2.1 Scheduling Feature

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LTE eRAN2.1 Scheduling Feature

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LTE eRAN2.1 Scheduling Feature

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LTE eRAN2.1 Scheduling Feature

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LTE air interface scheduling is the responsibility of the eNodeB, however additional scheduling and QoS (Quality of Service) handling could take place in the EPC (Evolved Packet Core).

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Typically, the main goal of scheduling is to meet the different users’ expectations. Historically the radio interface is the “weak link” or “bottle neck” in the overall end-to-end service. This is typically due to limited physical resources, i.e. limited bandwidth or channels. The scheduling in previous systems, such as GSM and UMTS, was easier. This was due to the fact that voice was the main service and required a dedicated channel. As such, the number of channels (or elements) on the base station limited the number of simultaneous calls.

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The eNodeB implements scheduling at the Medium Access Control (MAC) layer and provides time-and-frequency resources for uplink and downlink through scheduling. On the premise of guaranteed Quality of Service (QoS), scheduling aims to transmit data on the channel with better quality and maximize system throughput by using different channel qualities among UEs.

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LTE eRAN2.1 Scheduling Feature

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Huawei eNodeB supports four scheduling strategies: 

Max C/I

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Round Robin (RR)

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Proportional Fair (PF)

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Enhanced Proportional Fair (EPF)

The downlink scheduling strategy is decided by the DlschStrategy parameter, and the uplink scheduling strategy is decided by the UlschStrategy parameter.

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With Max C/I, RR, and PF scheduling strategies, dynamic scheduling is used for all services. With the EPF scheduling strategy, only the VoIP services use semi-persistent scheduling.

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LTE eRAN2.1 Scheduling Feature

Parameter

Meaning

DlschStrategy

Indicates the switch of the DL scheduling policy. According to the Max C/I scheduling policy, the UE with good-quality channels are scheduled and hence the spectral efficiency is very high. The QoS and fairness among users, however, cannot be ensured. The Max C/I scheduling policy can be used to verify the maximum capacity of the system. The RR scheduling policy is the fairest scheduling policy. When RR is adopted, the smallest system capacity is the smallest. Therefore, RR is used only to verify the upper bound of the scheduling fairness in the system. In terms of the scheduling effect, the PF scheduling policy is between the previous two policies. Therefore, PF can be used to verify the capacity, coverage, and fairness of the system. The EPF scheduling policy supports the features such as user QoS, system capacity, and channel frequency selection. The basic scheduling policy is mainly used for the performance test purpose. During common operation, the EPF scheduling policy is recommended.

UlschStrategy

Indicates the priority of the UL user scheduling algorithm and the policy of arranging the priority of users. According to the Max C/I scheduling policy, the UEs with good-quality channels are scheduled, thus the spectral efficiency is very high. The QoS of and fairness among users, however, cannot be ensured. The Max C/I scheduling policy can be used to verify the maximum capacity of the system. The fairest scheduling policy is RR. When RR is used, the system capacity, however, is the smallest. Therefore, RR is used only to verify the upper limit of the scheduling fairness in the system. In application effects, the PF scheduling policy is between the previous two policies. Thus, PF can be used to verify the capacity, coverage, and fairness of the system. According to the EPF scheduling policy, the features such as user QoS, system capacity, and channel frequency selection are considered. The basic scheduling policy is used during the performance test. In commercial scenarios, you are advised to use the EPF scheduling policy.

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LTE eRAN2.1 Scheduling Feature

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Semi-Persistent Scheduling 

Semi-persistent scheduling is introduced to reduce the overhead of control signaling. Semi-persistent scheduling is a process where one user uses the same time-and-frequency resources in a specified semi-persistent scheduling period (20 ms in Huawei eNodeB) until they are released. Semi-persistent scheduling is mainly used for processing services with a constant rate, regular packet arrival, and low delay requirements, such as the Voice over IP (VoIP). By adopting semi-persistent scheduling, VoIP services can save the overhead of control signaling and increase the VoIP capacity.

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Dynamic Scheduling 

In dynamic scheduling, scheduling is performed every Transmission Time Interval (TTI) of 1 ms and all the UEs to be scheduled are notified with the scheduling information through control signaling within this TTI. Dynamic scheduling has no requirements on the size and arrival time of data packets. Therefore, dynamic scheduling is applicable for all services.

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LTE eRAN2.1 Scheduling Feature

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LTE Default and Dedicated EPS bearers are capable of transporting a large variety of traffic types between the UE and the PDN. This could range from regular Internet browsing based on HTTP, through to real time voice services based on RTP. Above table outlines the traffic types which can potentially be encountered, including detail on the characteristics of the traffic and its associated QCI (QoS Class Identifier) value.

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The QCI is a parameter associated with each EPS bearer which will determine the bearer level packet forwarding treatment e.g. scheduling weights, admission thresholds, queue management etc. The QCI value of an EPS bearer will be established during the Default or Dedicated EPS bearer setup procedure.

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The Packet Delay Budget (PDB) defines an upper bound for the time that a packet may be delayed between the UE and the EPC.

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LTE eRAN2.1 Scheduling Feature

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Scheduling is a very complicated algorithm that involve a lot of input parameters, as shown in the above figure.

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LTE eRAN2.1 Scheduling Feature

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The signaling required for scheduling downlink resources is firstly dependent on the type of resources being scheduled. The LTE system defines various DCI (Downlink Control Information). These enable both downlink and uplink scheduling, as well as linking to different MIMO and diversity options.

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LTE eRAN2.1 Scheduling Feature

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LTE eRAN2.1 Scheduling Feature

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The type 1 resource block assignment information consists of three fields: 

The first field is used to indicate the selected RBG subset among P RBG subsets

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The second field with one bit is used to indicate a shift of the resource allocation span within a subset. A bit value of 1 indicates a shift is triggered. Otherwise a shift is not triggered.

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The third field includes a bitmap, where each bit of the bitmap addresses a single PRB in the selected RBG subset in such a way that MSB to LSB of the bitmap are mapped to the PRBs in the increasing frequency order

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LTE eRAN2.1 Scheduling Feature

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LTE eRAN2.1 Scheduling Feature

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LTE eRAN2.1 Scheduling Feature

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VoIP service 

The VoIP service experiencing semi-persistent scheduling has the highest priority. Semi-persistent scheduling is used in the talk spurts of the VoIP services.

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Control-plane data and IMS signaling 

Control-plane data consists of common control messages and UE-level control messages. Common control messages consist of broadcast messages, paging messages, and random access response messages. UE-level control messages consist of Signaling Radio Bearer 0 (SRB0), SRB1, and SRB2.

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The scheduling of IMS signaling is the same as that of UE-level control messages.

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HARQ retransmission data

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Other initial transmission services 

Other initial transmission services refer to the initial transmission services of other QCIs excluding VoIP services and IMS signaling.

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LTE eRAN2.1 Scheduling Feature

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Downlink scheduling allocates time-and-frequency resources at the Physical Downlink Shared Channel (PDSCH) for transmission of system messages and downlink data. Downlink scheduling described in this chapter is based on the EPF scheduling strategy.

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Downlink scheduling calculates available scheduling resources based on the current remaining power. In addition, the scheduling priority and Modulation and Coding Scheme (MCS) are determined based on the amount of data at the Radio Link Control (RLC) layer, QoS requirements of bearers, and UE channel quality. In downlink scheduling, the UE channel quality information is obtained through the CQIs reported by the UE. The prioritization and MCS selection of scheduling depend on the CQI information. Therefore, if reported CQIs cannot properly reflect the actual channel conditions, the downlink resource efficiency is low.

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LTE eRAN2.1 Scheduling Feature

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Generally, VoIP services adopt dynamic scheduling for the transient state and silent period and semi-persistent scheduling for the talk spurts.

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In downlink scheduling, if the VoIP service is in the talk spurts, semi-persistent scheduling is activated. If the VoIP service is in the silent period, the resources allocated to semipersistent scheduling are released. If the VoIP service transits from the talk spurts to the silent period, semi-persistent scheduling should be activated again. If PDCCH resources are insufficient in this case and the semi-persistent scheduling indication fails to be delivered, the UE uses dynamic scheduling. In a TTI of semi-persistent scheduling, dynamic scheduling is used instead of semi-persistent scheduling if large-size data packets appear

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LTE eRAN2.1 Scheduling Feature

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The resource of semi-persistent scheduling is a semi-persistent scheduling period in the time domain and is the system wideband in the frequency domain. When semi-persistent scheduling is activated, associated RBs are allocated to semi-persistent scheduling. When the VoIP service enters the silent period, related RBs are released. If a new VoIP service is admitted at this time, it can use these RBs.

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The eNodeB sets the upper and lower thresholds for time-and-frequency resources of semi-persistent scheduling in each TTI. Thus, failures of scheduling other services caused by excessive resource usage of semi-persistent scheduling can be prevented. The threshold algorithm is fixed setting in Huawei eNodeB. If resources of semi-persistent scheduling exceed the upper threshold, admission requests of new VoIP services are rejected. If resources of semi-persistent scheduling are fewer than the lower threshold, new VoIP services are admitted.

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VoIP services are prioritized by the waiting time. The VoIP service with longer waiting time has a higher priority. The process for selecting the MCS and determining the number of RBs is described as shown above.

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If initial transmission in semi-persistent scheduling of the VoIP service fails, retransmission of data is required. Data retransmissions of downlink VoIP services use dynamic scheduling and the downlink asynchronous adaptive HARQ retransmission.

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LTE eRAN2.1 Scheduling Feature

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The scheduling priority of control-plane data is only lower than that of VoIP services. Control-plane data is subject to dynamic scheduling. Control-plane data consists of common control messages and UE-level control messages. The scheduling of IMS signaling is the same as that of UE-level control messages.

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LTE eRAN2.1 Scheduling Feature

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HARQ retransmissions of Huawei eNodeB are classified into urgent HARQ retransmissions and non-urgent HARQ retransmissions.

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The scheduling priority of the urgent HARQ retransmission is lower than that of SRB0 and higher than that of SRB1 and SRB2. The scheduling priority of the non-urgent HARQ retransmission is lower than that of control-plane messages and higher than that of other initial transmission services. The HARQ retransmission (both urgent and non urgent) with longer waiting time has a higher scheduling priority. If all the retransmissions have the same waiting time, a retransmission is randomly selected.

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If the UE has VoIP services for semi-persistent scheduling, HARQ retransmissions of other services cannot be performed on the UE during the TTI of the semi-persistent scheduling. If SRB1, SRB2, and IMS signaling are scheduled in the current TTI, non-urgent HARQ retransmissions cannot be scheduled in this TTI.

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LTE eRAN2.1 Scheduling Feature

1. Eliminate the following UEs that do not need prioritization. 

UEs that experience semi-persistent scheduling in the current TTI

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UEs that experience HARQ retransmission scheduling in the current TTI

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UEs that run out of HARQ process numbers

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UEs that enter the measurement gap

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UEs that enter the DRX dormant period

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UEs that stay out of synchronization and have failed radio links

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LTE eRAN2.1 Scheduling Feature

2. Eliminate services (both non-Guaranteed Bit Rate (GBR) and GBR services) whose rates have met the guaranteed rates. These services do not need prioritization. The decision of whether rates meet the guaranteed rate is not made on the GBR services with QCI of 1. Such GBR services are prioritized directly. 

Note：

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Huawei eNodeB sets the minimum guaranteed rate Min_GBR for non-GBR services. In downlink scheduling, when the rate of the non-GBR service is greater than Min_GBR or there is no data to be sent in the buffer, the guaranteed rate of the non-GBR service is considered to be met. In other cases, the guaranteed rate of the non-GBR service is considered as not met. The Min_GBR in downlink scheduling is controlled by the DlMinGbr parameter.

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Within the specified time period T, if the rate of the scheduled GBR service is greater than T * (maximum number of DL-SCH transport block bits received within a TTI) or there is no data to be sent in the buffer, the guaranteed rate of the GBR service is considered to be met. In other cases, the guaranteed rate of the GBR service is considered not to be met.

3. Prioritize the remaining services. 

The prioritization of non-GBR services is different from that of GBR services.

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LTE eRAN2.1 Scheduling Feature

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Prioritization of Non-GBR Services The following factors are weighted in the priority calculation of non-GBR services in Huawei eNodeB: 

CQI 

The service with higher spectral efficiency of the corresponding wideband CQI has a higher priority.

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Average rate of non-GBR services 

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The non-GBR service with a larger average rate has a lower priority.

UE differentiation factor 

The UE differentiation factor reflects the priority of UEs of different levels. The UE with a higher level set by operators has a higher priority in scheduling.

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Weight factor 

Weight factors in downlink scheduling are classified into QCI class weight factors and service type-based weight factors. Huawei eNodeB can distinguish between Bit Torrent (BT) and non-BT services using a switch under the DlSchSwitch parameter.

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LTE eRAN2.1 Scheduling Feature

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If the eNodeB distinguishes between BT and non-BT services, the weight factor in downlink scheduling is determined by both the QCI class-based weight factor and service type-based weight factor. The QCI class-based weight factor is determined by the DlschPriorityFactor parameter. The weight factor for BT services is determined by the BtServiceWeight parameter, and the weight factor for non-BT services is determined by the OtherServiceWeight parameter.

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If the eNodeB does not distinguish between BT and non-BT services, the weight factor in downlink scheduling is determined by only the QCI classbased weight factor.

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A larger value of the weight factor leads to a higher priority of scheduling. The standard QCI and extended QCI can be configured with the QCI classbased weight factor respectively. The standard QCI is defined in specifications. The extended QCI is based on the standard QCI, which is mapped to the standard QCI.

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Prioritization of GBR Services The following factors are weighted in the priority calculation of GBR services in Huawei eNodeB: 

Channel quality 

The instantaneous channel quality of the UE is taken into account. The UE with better instantaneous channel quality has a higher priority. In the case of the same channel quality, the GBR service with QCI of 1 has a higher priority than other GBR services.

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Delay 

The closer the waiting time of the first packet in the buffer is to the Packet Delay Budget (PDB), the higher the priority is. The PDB value depends on the QCI. For details, see reference document [5].

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Relative priority 

The prioritization of GBR services is different from that of non-GBR services. This factor is added to compare the priority of GBR services with that of non-GBR services.

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LTE eRAN2.1 Scheduling Feature

Parameter ID

Meaning

DlSchSwitch

Indicates the switch related to DL scheduling in the cell. FreqSelSwitch: Indicates the switch that is used to control whether to enable and disable frequency selection and scheduling. If this switch is set to On, data is transmitted to the UE on the frequency band of good-quality channels. ServiceDiffSwitch: Indicates the switch that is used to control whether to enable and disable service differentiation. If this switch is set to On, service differentiation is applied. If this switch is set to Off, service differentiation is not applied.

DlschPriorityFactor

Indicates the weight factor used in the calculation of connection priorities during downlink scheduling.

BtServiceWeight

Indicates the weight of the BT service used in EPF scheduling. The value of this parameter is used in calculating the priority of the UE during scheduling and therefore determines the amount of physical resources to be allocated to the UE that requests the BT service. The BT service priority has a positive correlation with the value of this parameter. This parameter is valid only when the service differentiation function is enabled.

OtherServiceWeight

Indicates the weight of the non-BT service used in EPF scheduling. The value of this parameter is used in calculating the priority of the UE during scheduling and therefore determines the amount of resources to be allocated to the UE that requests the non-BT service. The priority of the non-BT service priority has a positive correlation with the value of this parameter. This parameter is valid only when the service differentiation function is enabled.

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LTE eRAN2.1 Scheduling Feature

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LTE eRAN2.1 Scheduling Feature

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When a UE is handed over to a target cell, initially, the channel quality is poor and the UE may not report CQIs timely. Therefore, to guarantee the data transmission performance during this period, Huawei eNodeB sets a static MCS on the UE until the UE reports CQIs stably. After this, if the UE reports valid CQIs, the system performs MCS selection according to the previously mentioned procedure.

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If part of resources in the RBs for scheduling are occupied by broadcast or synchronization signals, the actual code rate in data transmission increases with the same TBS. In this case, the eNodeB adjusts the MCS according to actual situations.

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The eNodeB supports the Adaptive Modulation and Coding (AMC) function where the MCS is automatically adjusted according to the load and remaining resources to maximize the resource usage.

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LTE eRAN2.1 Scheduling Feature

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Resource allocation in downlink scheduling is classified into frequency selective scheduling and frequency non-selective scheduling. During resource allocation, if frequency selective scheduling is enabled using a switch under the DlSchSwitch parameter and the following conditions are met, frequency selective scheduling is performed. In other cases, frequency non-selective scheduling is performed.

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In downlink scheduling, frequency selective scheduling allocates continuous sub carriers or Resource Blocks (RBs) to UEs. Frequency selective scheduling requires the eNodeB to obtain detailed channel quality information. RBs of high quality are selected based on the subband CQI, thus improving the system resource usage and UE peak rate.

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In downlink scheduling, frequency non-selective scheduling allocates discrete sub carriers or RBs to UEs. The eNodeB is required to obtain the full-band CQI. Channel information can be obtained through the wideband CQI, thus reducing signaling overhead.

Parameter ID

Meaning

DlSchSwitch

Indicates the switch related to DL scheduling in the cell. FreqSelSwitch: Indicates the switch that is used to control whether to enable and disable frequency selection and scheduling. If this switch is set to On, data is transmitted to the UE on the frequency band of good-quality channels. ServiceDiffSwitch: Indicates the switch that is used to control whether to enable and disable service differentiation. If this switch is set to On, service differentiation is applied. If this switch is set to Off, service differentiation is not applied.

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LTE eRAN2.1 Scheduling Feature

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LTE eRAN2.1 Scheduling Feature

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In downlink scheduling, prioritization and resource allocation are based on the CQI reported by the UE. The CQI is a key factor in prioritization in downlink scheduling. A UE that overestimates the channel quality experiences a rise in its scheduling priority, thus affecting fairness among UEs. On one hand, after a UE that overestimates the channel quality is scheduled, the IBLER exceeds the target value, thus leading to more retransmissions and increased service delay. On the other hand, the underestimation of UEs on the channel quality leads to a waste of system resources, which further affects the spectral efficiency of the entire system.

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Therefore, if the reported CQI fails to reflect the actual channel condition because of the following reasons, CQI adjustment is required: 

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The CQI report period is far greater than the scheduling period, which leads to deviation between the CQI at the reported time and CQI in scheduling. Therefore, the CQI adjustment algorithm, based on the ACKs and NACKs to initial transmissions, should check the deviation between the reported CQI and the actual channel quality and provides an adjusted CQI for scheduling. The UE is scheduled according to the reported CQI, and the IBLER target value of the UE is 10%. In actual system, however, the IBLER target value may reach 20% to maximize system capacity. In this case, the CQI reported by the UE fails to reflect the actual channel quality because the IBLER target value of the UE is inconsistent with that of the eNodeB.

The CQI adjustment algorithm is enabled or disabled using the CqiAdjAlgoSwitch parameter.

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LTE eRAN2.1 Scheduling Feature

Parameter

Meaning

CqiAdjAlgoSwitch

CqiAdjAlgoSwitch: Indicates the switch that is used to control whether to allow the eNodeB to adjust the UE-reported CQI based on the Initial Block Error Rate (IBLER). If this switch is set to On, the CQI adjustment algorithm is enabled. In the case, the eNodeB would adjust the UE-reported CQI based on the IBLER. If this switch is set to Off, the CQI adjustment algorithm is disabled. In this case, the eNodeB would not adjust the UE-reported CQI based on the IBLER. StepVarySwitch: Indicates the switch that is used to enable and disable the variable-step-based adjustment algorithm. If this switch is set to On, the variable-step-based adjustment algorithm is enabled to accelerate the convergence of IBLER. In this case, rapid adjustment at large steps is applied if there is a relatively large difference between the measured IBLER and target IBLER; fine-tuning at small steps is applied if the measured IBLER approaches the target IBLER. If this switch is set to Off, the adjustment is performed at a fixed step.

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LTE eRAN2.1 Scheduling Feature

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LTE eRAN2.1 Scheduling Feature

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LTE eRAN2.1 Scheduling Feature

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Uplink scheduling selects an appropriate UE at a proper time and allocates appropriate resources on the PUSCH to the UE.

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After the scheduling request from the UE is received, uplink scheduling is performed on the UE, and MCS selection and RB allocation are performed on the basis of the current channel quality of the UE, amount of data to be scheduled, and power headroom. In uplink scheduling, the channel quality of the UE is indicated by the SINR measured at the physical layer of the eNodeB. The amount of data to be scheduled depends on the Buffer Status Report (BSR) reported by the UE. The power headroom depends on the Power Headroom Report (PHR) reported by the UE.

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LTE eRAN2.1 Scheduling Feature

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VoIP services 

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Retransmission data 

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The UEs with control-plane data to be transmitted include the UE with the first uplink transmission, UE with SRB or IMS signaling to be transmitted, and UE with the Scheduling Request (SR) to be transmitted.

Other initial transmission data 

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Retransmission data includes data in retransmissions of TTI bundling, retransmissions in semi-persistent scheduling, suspended retransmissions, and retransmissions in dynamic scheduling.

Control-plane data 

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In uplink scheduling, VoIP services in the talk spurts are subject to semi-persistent scheduling. UEs carrying VoIP services are classified into the UE with activated semipersistent scheduling, UEs with initial transmissions in semi-persistent scheduling, and UEs with retransmissions in semi-persistent scheduling.

The UEs with other initial transmission data include the UEs with the initial transmission data in dynamic scheduling of services excluding IMS signaling and VoIP services, and the UEs with pre-allocation data.

Virtual MIMO pairing 

Virtual MIMO pairing is a feature where the eNodeB schedules two single-antenna UEs at the same time to enable the two UEs to transmit data on the same time-and-frequency resources. UEs are scheduled flexibly through the optimal virtual MIMO pairing and appropriate UEs are selected for pairing transmission.

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LTE eRAN2.1 Scheduling Feature

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Activation of Semi-Persistent Scheduling 

In uplink scheduling, the PDCP checks the first arrived data packet after the VoIP service is set up. 

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If the VoIP service is in the talk spurts, semi-persistent scheduling is activated. If there is no data transmission on the resources of semi-persistent scheduling for consecutive times after the activation, the resources of semi-persistent scheduling are implicitly released. Implicit release of resources means that the eNodeB directly releases resources without notifying the UE. If the VoIP service is in the silent period, dynamic scheduling is performed. When the VoIP service transits from the silent period to the talk spurts, the PDCP checks the data packet size and determines that the VoIP service is in the talk spurts. In this case, semi-persistent scheduling is activated.

In uplink scheduling, whether semi-persistent scheduling is used for the VoIP service in the talk spurts is determined by a switch under the UlSchSwitch parameter. If the VoIP service does not use semi-persistent scheduling, it can use dynamic scheduling with the same priority as other GBR services.

Initial Transmission in Semi-Persistent Scheduling 

For initial transmissions in activated semi-persistent scheduling, the eNodeB determines whether the resources of semi-persistent scheduling conflict with the PUCCH, PRACH, and TTI bundling retransmissions in the current TTI. If there are no conflicts, the resources continue to be used by the UEs of initial transmissions in semi-persistent scheduling. If there are conflicts, the resources of semi-persistent scheduling should be activated again. If the re-activation fails, dynamic scheduling is used and semi-persistent scheduling is retried in the next TTI. Semi-persistent scheduling uses the resource allocation scheme of frequency non-selective scheduling.

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LTE eRAN2.1 Scheduling Feature

Parameter ID

Meaning

UlSchSwitch

Indicates the switches related to UL scheduling in the cell, which are used to enable or disable the specific UL scheduling functions. SpsSchSwitch: Indicates whether to enable or disable semi-persistent scheduling during talk spurts of VoIP services. SinrAdjustSwitch: Indicates whether to adjust the measured SINR based on ACK/NACK to the UL HARQ process. PreAllocationSwitch: Indicates whether to enable or disable preallocation, which shortens the end-to-end delay of services when the UL load is light. If pre-allocation is enabled, the probability of UEs entering DRX is relatively low and therefore the service time of the UEs is relatively short. UlVmimoSwitch: Indicates whether to enable or disable uplink virtual MIMO. If uplink virtual MIMO is enabled, the eNodeB selects UEs for pairing according to pairing rules. Then the pair of UEs transmit data on the same frequency-time resources, increasing system throughput and spectral efficiency. TtiBundlingSwitch: Indicates whether to enable or disable TTI bundling. If TTI bundling is enabled, more transmission opportunities are available to UEs within the delay budget for VoIP services on the air interface, improving uplink coverage. Im2IcSwitch: Indicates whether to enable or disable the second-order intermodulation (IM2) components elimination for UEs. During concurrent data transmissions in both UL and DL, two IM2 components are generated symmetrically beside the Direct Current (DC) subcarrier on the DL receive channel due to the interference from UL radio signals. If this switch is turned on, IM2 components elimination is performed for UEs. If this switch is turned off, IM2 components elimination is not performed for UEs.

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LTE eRAN2.1 Scheduling Feature

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In Huawei eNodeB uplink scheduling, retransmission data includes data in retransmissions of TTI bundling, retransmissions in semi-persistent scheduling, suspended retransmissions, and retransmissions in dynamic scheduling. Retransmission data uses the resource allocation scheme of frequency non-selective scheduling.

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Uplink retransmissions use the synchronous non-adaptive HARQ retransmission. In the FDD system, the interval between retransmissions is fixed to eight TTIs. If TTI bundling is used, the interval is changed to 16 TTIs. In the TDD system, the retransmission interval is related to uplink and downlink configurations. For details, see reference document [1]. Uplink retransmissions can also use the synchronous adaptive HARQ retransmission. The synchronous adaptive HARQ retransmission function can be enabled or disabled using the AdaptHarqSwitch parameter.

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If resource conflicts occur in the uplink retransmission, the eNodeB re-allocates resources to the UE. If resource allocation fails, the eNodeB sends ACK to the UE to suspend the retransmission. UEs with suspended retransmissions are sorted by the number of retransmissions. The UE with a larger number of retransmissions has a higher priority in scheduling. If resources for the retransmission in semi-persistent scheduling are in conflict with those of the PUCCH, the resources for the initial transmission in semi-persistent scheduling are activated again.

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Retransmissions use the same number of RBs and MCS as those in the initial transmission.

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LTE eRAN2.1 Scheduling Feature

Parameter ID

Meaning

Indicates the switch that is used to control whether to enable or disable UL adaptive HARQ. If this switch is set to ADAPTIVE_HARQ_SW_OFF, UL data is retransmitted by non-adaptive synchronous HARQ. If this switch is set to ADAPTIVE_HARQ_SW_ON, UL data is retransmitted by adaptive synchronous HARQ. If this switch is set to ADAPTIVE_HARQ_SW_SEMION, adaptive HARQ is triggered when a AdaptHarqSwitch UL grant is delivered to an HARQ process that is previously suspended due to reasons such as resource collision, activation of a measurement gap, and PDCCH congestion. Setting this parameter to ADAPTIVE_HARQ_SW_ON helps reduce resource consumption due to retransmission, increase the cell throughput, and prevent retransmission conflicts. This, on the other hand, will increase signaling overhead and therefore consume more PDCCH resources.

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LTE eRAN2.1 Scheduling Feature



The UE with control-plane data to be transmitted includes the UE with the first uplink transmission, UE with SRB or IMS signaling to be transmitted, and UE with the SR to be transmitted.



The UE with the first transmission refers to the UE that needs to transmit msg3. These UEs are scheduled in the order of msg3 transmission time. The UE with the first transmission uses the resource allocation scheme of frequency non-selective scheduling. Four RBs are allocated to a UE with the first transmission. In case of non-contention based random access, IMCS = 1. In case of contention based random access, IMCS = 1 if group A is used or IMCS = 5 if group B is used.



UEs with SRB or IMS signaling to be transmitted are sorted by the average Signal-to-Noise Ratio (SNR) in descending order. The UE with a larger average SNR has a higher priority in scheduling. For UEs with Radio Resource Control (RRC) messages or IMS signaling to be transmitted, resource allocation adopts frequency selective scheduling and the MCS is the same as that in dynamic scheduling.



UEs with the SR to be transmitted are sorted by the number of received SRs since the last scheduling. The UE with a larger number of SRs has a higher priority in scheduling. For UEs with the SR to be transmitted, the resource allocation adopts the frequency selective scheduling and the MCS is the same as that in dynamic scheduling.

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LTE eRAN2.1 Scheduling Feature



UEs with other initial transmission services include the UEs with the initial transmission data in dynamic scheduling of services excluding VoIP services and IMS signaling and the UEs with pre-allocation data. The QCI of emergency calls must be set to 1 at the EPC to guarantee the highest priority of emergency calls.



The happy user refers to the UE with non-GBR services that meets the Min_GBR but fails to meet the Aggregate Maximum Bit Rate (AMBR). The Min_GBR in uplink scheduling is controlled by the UlMinGbr parameter.



The UE reporting CQIs in event-triggered mode refers to the UE that reports the CQI through the PUSCH in case of no valid CQIs.



Pre-allocation refers to a process where the eNodeB reserves resources for UEs with high requirements for delay based on the uplink load status.

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LTE eRAN2.1 Scheduling Feature



In uplink scheduling, the token bucket algorithm is used to determine whether the rate of services meets the guaranteed rate. The principle of the token bucket is as follows: Water injected into the bucket in a specified period is the size of the bucket. During this period, the remaining amount of water in the bucket is equal to the accumulated water in the bucket minus the amount of the scheduled data. The water injection rate is in proportion to the service rate. When the remaining amount of water is greater than 0, the rate of the service does not meet the required rate.

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LTE eRAN2.1 Scheduling Feature



The resource allocation of the UE with unsatisfied GBR, UE with unsatisfied Min_GBR, and happy users adopts frequency selective scheduling. The following factors are weighted in the scheduling priority of these UEs: 

Effective rate 

The UE with a low effective rate has a higher priority in scheduling. The effective rate refers to the average rate of the UE data received by the eNodeB in a specified period.



Total guaranteed rate of services with unsatisfied rates 

The UE with a higher total guaranteed rate has a higher priority in scheduling. The UEs with the unsatisfied rate include the UE with unsatisfied GBR, UE with unsatisfied Min_GBR, and happy user.



Average channel quality 



The UE with a larger average SINR has a higher priority in scheduling.

Weight factor 

The UE with a larger weight factor value has a higher priority in scheduling. When services with more than one QCI are running on a UE, the weight factor of the QCI with the highest priority is used. The weight factor has no impact on the priority of the GBR services. In the priority calculation of nonGBR services, the weight factor is determined by the UlschPriorityFactor parameter, which supports the extended QCI.

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LTE eRAN2.1 Scheduling Feature

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LTE eRAN2.1 Scheduling Feature



The pre-allocation function is controlled by a switch under the UlSchSwitch parameter. The total resource for pre-allocation is specified by the PreAllocationBandwidthRatio parameter, which indicates the maximum proportion of the total RB number available for a pre-allocation UE in a TTI to the system bandwidth. The amount of data that can be pre-allocated for a UE in a pre-allocation queue is specified by the PreAllocationSize parameter.



When the pre-allocation function is enabled, the UEs with unsatisfied GBR or AMBR are placed in the pre-allocation queue if PUSCH resources are available after the happy users are scheduled. Such UEs should meet the following requirements: 

The UE is not scheduled in the current TTI.



The UE does not enter the DRX mode.



The UE meets the minimum interval between pre-allocations. 



The UE has a pre-allocation weight greater than 0. 



The minimum interval between pre-allocations is specified by the PreAllocationMinPeriod parameter. When the value is 1, resources can be preallocated in each TTI. When the value is 2, resources can be pre-allocated once every two TTIs. The pre-allocation weight is specified by the PreAllocationWeight parameter, which is QCI specific. The pre-allocation weight of the UE is determined by the preallocation weight of the QCI service of the highest priority.

The resource pre-allocation priorities of UEs in the pre-allocation queue are determined by the number of pre-allocations and the pre-allocation weight. A smaller number of pre-allocations of a UE and a larger pre-allocation weight indicate a higher priority. If UEs have the same settings of the priority and pre-allocation weight, the UEs are randomly selected for pre-allocation. When resources are limited, the number of pre-allocations is in proportion to the pre-allocation weight. Preallocation is unavailable for UEs experiencing semi-persistent scheduling.

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LTE eRAN2.1 Scheduling Feature

Parameter ID

Meaning

DlMinGbr

Indicates the downlink minimum guaranteed bit rate of the non-GBR service.

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LTE eRAN2.1 Scheduling Feature

Parameter ID

Meaning

UlschPriorityFa Indicates the weight factor used in the calculation of connection priorities during ctor uplink scheduling.

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LTE eRAN2.1 Scheduling Feature

Parameter ID

Meaning

UlSchSwitch

Indicates the switches related to UL scheduling in the cell, which are used to enable or disable the specific UL scheduling functions. SpsSchSwitch: Indicates whether to enable or disable semi-persistent scheduling during talk spurts of VoIP services. SinrAdjustSwitch: Indicates whether to adjust the measured SINR based on ACK/NACK to the UL HARQ process. PreAllocationSwitch: Indicates whether to enable or disable preallocation, which shortens the end-to-end delay of services when the UL load is light. If pre-allocation is enabled, the probability of UEs entering DRX is relatively low and therefore the service time of the UEs is relatively short. UlVmimoSwitch: Indicates whether to enable or disable uplink virtual MIMO. If uplink virtual MIMO is enabled, the eNodeB selects UEs for pairing according to pairing rules. Then the pair of UEs transmit data on the same frequency-time resources, increasing system throughput and spectral efficiency. TtiBundlingSwitch: Indicates whether to enable or disable TTI bundling. If TTI bundling is enabled, more transmission opportunities are available to UEs within the delay budget for VoIP services on the air interface, improving uplink coverage. Im2IcSwitch: Indicates whether to enable or disable the second-order intermodulation (IM2) components elimination for UEs. During concurrent data transmissions in both UL and DL, two IM2 components are generated symmetrically beside the Direct Current (DC) subcarrier on the DL receive channel due to the interference from UL radio signals. If this switch is turned on, IM2 components elimination is performed for UEs. If this switch is turned off, IM2 components elimination is not performed for UEs.

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LTE eRAN2.1 Scheduling Feature



The eNodeB flexibly schedules UEs using the pairing strategy and selects appropriate UEs for pairing transmission. Virtual MIMO pairing is controlled by a switch under the UlSchSwitch parameter.



Virtual MIMO pairing has requirements for UE bandwidth, channel quality, and amount of data to be transmitted. Virtual MIMO pairing is performed when these requirements are met. When the shortest time of virtual MIMO pairing is met, the eNodeB determines whether to disable virtual MIMO pairing in each TTI. If virtual MIMO pairing is not disabled, pairing continues. Rules for virtual MIMO pairing are as follows: 

 







If the channel spectral efficiency does not meet the requirements for pairing , pairing is disabled. If there are conflicts with retransmissions in TTI bundling, pairing is disabled. If there are conflicts with initial transmissions in semi-persistent scheduling, pairing is not performed in the current TTI but can continue in the next TTI. If there are conflicts with retransmissions, pairing is not performed in the current TTI but can continue in the next TTI. If two UEs cannot be allocated appropriate cyclic shifts, pairing is not performed in the current TTI but can continue in the next TTI. If resources for continuous pairing are occupied by UEs with higher priorities or there are conflicts with PRACHs, pairing is not performed in the current TTI but can continue in the next TTI.



The UEs whose virtual MIMO pairing is disabled are prioritized in the initial transmission services process



The UE with TTI bundling cannot perform virtual MIMO pairing.

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LTE eRAN2.1 Scheduling Feature

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LTE eRAN2.1 Scheduling Feature



In uplink scheduling, when scheduling a user, the eNodeB determines the MCS used in the upcoming transmission based on the SINR and power headroom of the uplink channel. The procedure for selecting the MCS is as follows: 1. The eNodeB selects the IMCS according to the user SINR, SINR adjustment, and MCS related SINR threshold. 2. The eNodeB performs MCS adjustment as follows: 

If the subframe is the Sounding Reference Signal (SRS) subframe, the last OFDM symbol cannot transmit data. Therefore, the MCS level needs to be lowered on the basis of the initial selection.



The MCS level can be raised or lowered based on the power headroom of the UE.



In the case of neighboring interference indication, the MCS level is lowered to improve the system throughput.



The uplink MCS in Huawei eNodeB supports 64QAM. This is an optional feature and can be enabled or disabled using the Qam64Enabled parameter.



In uplink transmission, the eNodeB supports AMC where the MCS is automatically adjusted based on the UE channel condition to maximize the resource usage.

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LTE eRAN2.1 Scheduling Feature

Parameter ID

Meaning

Qam64Enable Indicates whether 64QAM of the PUSCH is enabled. d

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LTE eRAN2.1 Scheduling Feature

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LTE eRAN2.1 Scheduling Feature



Due to the impact of channel fading on signals, the SINR at the reporting time changes significantly, compared with that at the scheduling time.



For the Huawei uplink scheduling algorithm, the SINR adjustment scheme is adopted to adjust the SINR reported by the physical layer in order to correct the SINR measurement errors. In this way, the measured IBLER value approaches the target IBLER value. The IBLER target value is set using the SinrAdjustTargetIbler parameter.



The SINR adjustment function is controlled by a switch under the UlSchSwitch parameter.

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LTE eRAN2.1 Scheduling Feature

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LTE eRAN2.1 Scheduling Feature



In uplink scheduling, TTI bundling can be used to improve the transmission quality when the UE channel quality is poor or the transmit (TX) power is limited (such as at the cell edge). TTI bundling refers to a scenario where a single transport block is coded and transmitted in a set of consecutive subframes. The bundled subframes are handled as one unit. In this way, signaling overhead can be reduced. TTI bundling is controlled by a switch under the UlSchSwitch parameter. If TTI bundling is configured for UEs, virtual MIMO pairing cannot be performed.



In Huawei eNodeB, the TTI bundling size is fixed to four subframes. Users can transmit the same data in the four subframes. If the retransmission is required for the data transmitted through TTI bundling, the retransmission is also a type of TTI bundling. Accordingly, the retransmission interval changes and the number of Hybrid Automatic Repeat Request (HARQ) progresses decreases. In the FDD system, the retransmission interval is changed from 8 TTIs to 16 TTIs. In the TDD system, the retransmission interval varies according to uplink and downlink assignment.

Parameter ID

UlSchSwitch

Meaning Indicates the switches related to UL scheduling in the cell, which are used to enable or disable the specific UL scheduling functions. SinrAdjustSwitch: Indicates whether to adjust the measured SINR based on ACK/NACK to the UL HARQ process.

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LTE eRAN2.1 Scheduling Feature

Parameter ID

Meaning Indicates the switches related to UL scheduling in the cell, which are used to enable or disable the specific UL scheduling functions.

UlSchSwitch

TtiBundlingSwitch: Indicates whether to enable or disable TTI bundling. If TTI bundling is enabled, more transmission opportunities are available to UEs within the delay budget for VoIP services on the air interface, improving uplink coverage.

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LTE eRAN2.1 Scheduling Feature

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LTE eRAN2.1 Scheduling Feature



Four scheduling strategies are supported: Max C/I, PF, RR, and EPF. The downlink scheduling strategy is set using the DlschStrategy parameter, and the uplink scheduling strategy is set using the UlschStrategy parameter.



Max C/I, PF, and RR are basic scheduling strategies. With Max C/I, UEs with better channel quality are selected, thus achieving high spectral efficiency. The QoS and fairness of the UE, however, cannot be guaranteed. The Max C/I scheduling strategy can be used to verify the maximum system throughput. With the RR scheduling strategy, the fairness among UEs can be guaranteed, but the system throughput is the lowest. Therefore, RR is usually used to verify the upper limit of scheduling fairness. The PF scheduling strategy is a trade-off between fairness and system throughput. PF is used to verify the system capacity and fairness among users.



The basic scheduling strategies are usually used in performance tests. The EPF scheduling strategy is recommended in routine operation scenarios. The EPF scheduling strategy takes the UE QoS, system capacity, and channel frequency selective characteristics into consideration.

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LTE eRAN2.1 Scheduling Feature



Resource Allocation 

In downlink scheduling, resource allocation is classified into frequency selective scheduling and frequency non-selective scheduling. The scheduling strategies of Max C/I, PF, and EPF consider frequency selective scheduling preferentially before considering frequency non-selective scheduling. The RR scheduling strategy considers only frequency non-selective scheduling. The frequency selective scheduling is controlled by a switch under the DlSchSwitch parameter.

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LTE eRAN2.1 Scheduling Feature



Prioritization of Non-GBR Service 

Prioritization is involved only in the EPF scheduling strategy. In downlink scheduling, the priority of the non-GBR service depends on the factors such as the CQI, average rate, retransmission rate, UE differentiation factor, and weight factor.



Different QCIs have different QoS requirements. Therefore, the priorities of services mapped to different QCIs are differentiated using the weight factor. The weight factor is set using the DlschPriorityFactor parameter. The QCI with a larger value of DlschPriorityFactor has a higher priority in scheduling, and the QCI service has a greater impact on the system throughput.



Different types of services require different scheduling priorities. Huawei eNodeB can distinguish between BT and non-BT services using a switch under the DlSchSwitch parameter.



If the eNodeB distinguishes between BT and non-BT services, the weight factor for BT services is determined by the BtServiceWeight parameter and the weight factor for non-BT services is determined by the OtherServiceWeight parameter. The weight factor in downlink scheduling is determined by both the QCI classbased weight factor and service type-based weight factor. The QCI class-based weight factor is determined by the DlschPriorityFactor parameter.



If the QCI class is the same, a larger value of the BtServiceWeight parameter indicates a higher priority for BT services. That is, more RBs are allocated to BT services.



If the QCI class is the same, a larger value of the OtherServiceWeight parameter indicates a higher priority for non-BT services. That is, more resources are allocated to non-BT services.



If the eNodeB does not distinguish between BT and non-BT services, the weight factor in downlink scheduling is determined by only the QCI class-based weight factor.



CQI Adjustment 

The CQI adjustment function can be enabled or disabled using the CqiAdjAlgoSwitch parameter. The function is recommended to be enabled in an operating network.



CQI adjustment enables the IBLER of the UE to approach the target value, thus achieving optimal system throughout. The CQI reported by the UE may not reflect the actual channel quality. Therefore, CQI adjustment is required to correct the reported CQI, thus improving system capacity. If the CQI reporting period has great deviation from the actual scheduling period, CQI adjustment is required, thus compensating for part of information loss and improving system throughput.

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LTE eRAN2.1 Scheduling Feature



Scheduling Scheme of VoIP Services 

In uplink scheduling, whether the VoIP service in the talk spurts uses semipersistent scheduling is controlled by a switch under the UlSchSwitch parameter. If semi-persistent scheduling is used for the VoIP service, overhead of the control signaling can be reduced and the system VoIP capacity increases.



Prioritization of Non-GBR Services 

In the priority calculation of non-GBR services, the weight factor is determined by the UlschPriorityFactor parameter. The QCI with a larger value of UlschPriorityFactor has a higher priority in scheduling, and the QCI service has a greater impact on the system throughput.

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LTE eRAN2.1 Scheduling Feature



In uplink scheduling, the synchronous adaptive HARQ retransmission can be enabled or disabled using the AdaptHarqSwitch parameter. If the parameter is set to Off, the synchronous non-adaptive HARQ retransmission is used in uplink retransmissions. If the parameter is set to On, the synchronous adaptive HARQ retransmission is used in uplink retransmissions. If the parameter is set to SemiOn, synchronous adaptive HARQ retransmission is used for suspended retransmission data and HARQ processes with resource conflict, and the synchronous non-adaptive HARQ retransmission is used for other data.



The synchronous non-adaptive HARQ retransmission can reduce the overhead of the control signaling. In the synchronous non-adaptive HARQ retransmission, the eNodeB reserves resources for retransmissions and the retransmission uses the same resources and MCS as the initial transmission. In the synchronous adaptive HARQ retransmission, the eNodeB re-allocates resources and determines the MCS for the UE according to the current channel quality. When the cell mainly has uplink services or has no downlink services, that is, the cell has sufficient resources on the PDCCH, the synchronous adaptive HARQ retransmission is used.

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LTE eRAN2.1 Scheduling Feature

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LTE eRAN2.1 Scheduling Feature



Pre-Allocation 

The pre-allocation function is controlled by a switch under the UlSchSwitch parameter. The pre-allocation algorithm is applicable in scenarios of light uplink load, which reduces the end-to-end delay. In case of heavy load in uplink, resources are unavailable for pre-allocation. If the pre-allocation function is enabled, the probability of the UE entering the DRX status is reduced, the battery life of the UE is shortened, and the interferences to neighboring cells increase.



The total resources for pre-allocation are specified by the PreAllocationBandwidthRatio parameter, which indicates the maximum proportion of the total RB number available for a pre-allocation UE in a TTI to the system bandwidth. If the value of this parameter increases, the bandwidth available for pre-allocation UEs also increases. Therefore, more UEs can be pre-allocated, but interferences to neighboring cells become stronger. If the value of this parameter decreases, the bandwidth available for pre-allocation UEs also decreases. Therefore, fewer UEs are pre-allocated with resources, and interferences to neighboring cells become weaker.

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LTE eRAN2.1 Scheduling Feature



The amount of data that can be pre-allocated to a UE in a pre-allocation queue is specified by the PreAllocationSize parameter. This parameter has an impact on the bandwidth resources for a pre-allocation UE. The amount of data for preallocation should be determined on the basis of the estimated service data amount. When the value of this parameter matches the actual data amount of the service, the delay is the shortest. When the value of this parameter is less than the actual data amount of the service, the delay increases. When the value of this parameter is greater than the actual data amount of the service, resources are wasted and interferences increase. The default value is recommended.



The minimum interval between pre-allocations is specified by the PreAllocationMinPeriod parameter. The parameter is used to specify the impact of pre-allocation on the UE battery life. A larger value of this parameter indicates a longer service delay. Therefore, the UE is less likely to be pre-allocated with resources and the UE battery life lasts longer. A smaller value of this parameter indicates a shorter service delay. Therefore, the UE is more likely to be pre-allocated with resources and the UE battery life lasts shorter.



The pre-allocation weight is specified by the PreAllocationWeight parameter. This parameter has an impact on the QCI-specific pre-allocation opportunity and also the QCI-specific delay. A larger pre-allocation weight indicates a shorter service delay whereas a smaller pre-allocation weight indicates a longer service delay.



SINR Adjustment 

The SINR adjustment function is controlled by a switch under the UlSchSwitch parameter. The function is recommended to be enabled in an operating network.



Due to factors such as the channel estimation error or delay, the MCS used by the UE may not match the actual channel quality, thus leading to deviation of the IBLER from the target value. The error can be corrected using SINR adjustment.



The IBLER target value is set using the SinrAdjustTargetIbler parameter. The larger value indicates greater SINR adjustment. Therefore, the selected MCS is of higher order. The IBLER target value can be increased to guarantee the cell throughput.



TTI Bundling 

The TTI bundling function is controlled by a switch under the UlSchSwitch parameter.



When the TTI bundling is enabled for the UE in case of poor channel quality and limited power, more transmission opportunities are obtained within the delay budget at the air interface, thus improving uplink coverage.

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LTE eRAN2.1 Scheduling Feature

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LTE eRAN2.1 ICIC Feature



Parameter description

MO

Parameter ID

CellAlgo Switch

CqiAdjAlgoSwitch: Indicates the switch that is used to control whether to allow the eNodeB to adjust the UE-reported CQI based on the Initial Block Error Rate (IBLER). If this switch is set to On, the CQI adjustment algorithm is enabled. In the case, the eNodeB would adjust the UE-reported CQI based on the IBLER. If this switch is set to Off, the CQI adjustment algorithm is disabled. In this case, the eNodeB would not adjust the UEreported CQI based on the IBLER. CqiAdjAlgoS StepVarySwitch: Indicates the switch that is used to enable and witch disable the variable-step-based adjustment algorithm. If this switch is set to On, the variable-step-based adjustment algorithm is enabled to accelerate the convergence of IBLER. In this case, rapid adjustment at large steps is applied if there is a relatively large difference between the measured IBLER and target IBLER; fine-tuning at small steps is applied if the measured IBLER approaches the target IBLER. If this switch is set to Off, the adjustment is performed at a fixed step.

CellAlgo Switch

Indicates the switches related to UL scheduling in the cell, which are used to enable or disable the specific UL scheduling functions. SpsSchSwitch: Indicates whether to enable or disable semipersistent scheduling during talk spurts of VoIP services. SinrAdjustSwitch: Indicates whether to adjust the measured SINR based on ACK/NACK to the UL HARQ process. PreAllocationSwitch: Indicates whether to enable or disable preallocation, which shortens the end-to-end delay of services when the UL load is light. If pre-allocation is enabled, the probability of UEs entering DRX is relatively low and therefore the service time of the UEs is relatively short. UlVmimoSwitch: Indicates whether to enable or disable uplink virtual MIMO. If uplink virtual MIMO is enabled, the eNodeB selects UEs for pairing according to pairing rules. Then the pair of UlSchSwitch UEs transmit data on the same frequency-time resources, increasing system throughput and spectral efficiency. TtiBundlingSwitch: Indicates whether to enable or disable TTI bundling. If TTI bundling is enabled, more transmission opportunities are available to UEs within the delay budget for VoIP services on the air interface, improving uplink coverage. Im2IcSwitch: Indicates whether to enable or disable the secondorder intermodulation (IM2) components elimination for UEs. During concurrent data transmissions in both UL and DL, two IM2 components are generated symmetrically beside the Direct Current (DC) subcarrier on the DL receive channel due to the interference from UL radio signals. If this switch is turned on, IM2 components elimination is performed for UEs. If this switch is turned off, IM2 components elimination is not performed for UEs.

Description

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LTE eRAN2.1 ICIC Feature



Parameter description

MO

Parameter ID

CellAlgo Switch

Indicates the switch related to DL scheduling in the cell. FreqSelSwitch: Indicates the switch that is used to control whether to enable and disable frequency selection and scheduling. If this switch is set to On, data is transmitted to the UE on the frequency DlSchSwitch band of good-quality channels. ServiceDiffSwitch: Indicates the switch that is used to control whether to enable and disable service differentiation. If this switch is set to On, service differentiation is applied. If this switch is set to Off, service differentiation is not applied.

Description

Indicates the switch of the DL scheduling policy. According to the Max C/I scheduling policy, the UE with good-quality channels are scheduled and hence the spectral efficiency is very high. The QoS and fairness among users, however, cannot be ensured. The Max C/I scheduling policy can be used to verify the maximum capacity of the system. The RR scheduling policy is the fairest scheduling policy. When RR is adopted, the smallest system capacity is the CellDlsch DlschStrateg smallest. Therefore, RR is used only to verify the upper bound of Algo y the scheduling fairness in the system. In terms of the scheduling effect, the PF scheduling policy is between the previous two policies. Therefore, PF can be used to verify the capacity, coverage, and fairness of the system. The EPF scheduling policy supports the features such as user QoS, system capacity, and channel frequency selection. The basic scheduling policy is mainly used for the performance test purpose. During common operation, the EPF scheduling policy is recommended. Indicates the weight of the BT service used in EPF scheduling. The value of this parameter is used in calculating the priority of the UE during scheduling and therefore determines the amount of CellDlsch BtServiceWei physical resources to be allocated to the UE that requests the BT Algo ght service. The BT service priority has a positive correlation with the value of this parameter. This parameter is valid only when the service differentiation function is enabled. Indicates the weight of the non-BT service used in EPF scheduling. The value of this parameter is used in calculating the priority of the UE during scheduling and therefore determines the CellDlsch OtherService amount of resources to be allocated to the UE that requests the Algo Weight non-BT service. The priority of the non-BT service priority has a positive correlation with the value of this parameter. This parameter is valid only when the service differentiation function is enabled.

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LTE eRAN2.1 ICIC Feature



Parameter description

MO

Parameter ID

CellUlsch AdaptHarqS Algo witch

Description Indicates the switch that is used to control whether to enable or disable UL adaptive HARQ. If this switch is set to ADAPTIVE_HARQ_SW_OFF, UL data is retransmitted by nonadaptive synchronous HARQ. If this switch is set to ADAPTIVE_HARQ_SW_ON, UL data is retransmitted by adaptive synchronous HARQ. If this switch is set to ADAPTIVE_HARQ_SW_SEMION, adaptive HARQ is triggered when a UL grant is delivered to an HARQ process that is previously suspended due to reasons such as resource collision, activation of a measurement gap, and PDCCH congestion. Setting this parameter to ADAPTIVE_HARQ_SW_ON helps reduce resource consumption due to retransmission, increase the cell throughput, and prevent retransmission conflicts. This, on the other hand, will increase signaling overhead and therefore consume more PDCCH resources.

Indicates the target IBLER of the SINR adjustment algorithm. A CellUlsch SinrAdjustTar greater parameter value indicates a greater SINR adjustment Algo getIbler value, and thus a higher-level MCS is used. Indicates the priority of the UL user scheduling algorithm and the policy of arranging the priority of users. According to the Max C/I scheduling policy, the UEs with good-quality channels are scheduled, thus the spectral efficiency is very high. The QoS of and fairness among users, however, cannot be ensured. The Max C/I scheduling policy can be used to verify the maximum capacity of the system. The fairest scheduling policy is RR. When RR is used, the system capacity, however, is the smallest. Therefore, CellUlsch UlschStrateg RR is used only to verify the upper limit of the scheduling fairness Algo y in the system. In application effects, the PF scheduling policy is between the previous two policies. Thus, PF can be used to verify the capacity, coverage, and fairness of the system. According to the EPF scheduling policy, the features such as user QoS, system capacity, and channel frequency selection are considered. The basic scheduling policy is used during the performance test. In commercial scenarios, you are advised to use the EPF scheduling policy. PreAllocation Indicates the ratio of the maximum bandwidth resources that the CellUlsch BandwidthRa uplink scheduler can allocated to pre-allocation users to the total Algo tio system bandwidth. CellUlsch PreAllocation Indicates the data amount pre-allocated to each user. Algo Size Indicates the minimum interval between two pre-allocations. That CellUlsch PreAllocation is, the actual interval between two pre-allocations of one UE must Algo MinPeriod be longer than or equal to the value of this parameter.

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LTE eRAN2.1 ICIC Feature

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Parameter description

MO

Parameter ID

Extended DlMinGbr QCI

Description Indicates the downlink minimum guaranteed bit rate of the non-GBR service.

Extended DlschPriorityF Indicates the weight factor used in the calculation of connection Qci actor priorities during downlink scheduling. Indicates the priority of the logical channel. The UE scheduler guarantees prioritized bit rates of logical channels in descending Extended LogicalChann order of logical channel priority. Resources are allocated in Qci elPriority descending order of logical channel priority after the prioritized bit rates of all services are guaranteed. For details, see 3GPP TS 36.321. Extended PrioritisedBit Qci Rate

Indicates the prioritized bit rate of the logical channel. The UE scheduler guarantees prioritized bit rates of logical channels in descending order of logical channel priority. For details, see 3GPP TS 36.321.

Extended UlMinGbr QCI

Indicates the uplink minimum guaranteed bit rate of the non-GBR service.

Extended UlschPriorityF Indicates the weight factor used in the calculation of connection Qci actor priorities during uplink scheduling. Indicates whether to set a logical channel group profile.

GlobalPro LcgProfile cSwitch

Currently, two logical channel group profiles are available: LCG_PROFILE_0 and LCG_PROFILE_1. If LCG_PROFILE_0 is used, only one logical channel group is assigned to non-GBR services. If LCG_PROFILE_1 is used, two logical channel groups are assigned to non-GBR services. One group is assigned to high-priority non-GBR services, and the other group is assigned to low-priority non-GBR services.

PUSCHC Qam64Enabl FG ed

Indicates whether 64QAM of the PUSCH is enabled. For details, see 3GPP TS 36.211.

Standard DlMinGbr Qci

Indicates the downlink minimum guaranteed bit rate of the non-GBR service.

Standard DlschPriorityF Indicates the weight factor used in the calculation of connection Qci actor priorities during downlink scheduling. Standard PrioritisedBit Qci Rate

Indicates the prioritized bit rate of the logical channel. The UE scheduler guarantees prioritized bit rates of logical channels in descending order of logical channel priority. For details, see 3GPP TS 36.321.

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LTE eRAN2.1 ICIC Feature



Parameter description

MO

Parameter ID

Standard UlMinGbr Qci

Description Indicates the uplink minimum guaranteed bit rate of the non-GBR service.

Standard UlschPriority Indicates the weight factor used in the calculation of connection Qci Factor priorities during uplink scheduling. Indicates the pre-allocation weight. The pre-allocation weight of a UE is the pre-allocation weight of services carried by the highestpriority logical channel. If services carried by highest-priority logical channels have different pre-allocation weights, the UE Standard PreAllocation takes the highest pre-allocation weight. When resources are Qci Weight insufficient, pre-allocation weights affect the pre-allocation probabilities of users. The pre-allocation probability has a positive correlation with the pre-allocation weight. This parameter is QCIspecific.

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LTE eRAN2.1 Scheduling Feature

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