channel elements

This is similar to asking how long is a piece of string. Hi Siobhan There are two basic limiting factors determining the capacity of a Node B: ? Channel Elements (CE) ? The Air Interface Interference and power The channel data rate will have an impact on both of these. Channel Elements (CE) Capacity To simplify this I will take the case of a voice service rate (12.2 kbps). This service requires 1 CE and since the latest version of the Ericsson Node B c ontains 768 CEs, this number of voice connections could be supported. What must be remembered is that a connection in soft handover will require CEs o n each node B involved in the connection, so the amount of soft handover in the network will have an impact on this. Latest figures suggest an overhead of 30% f or soft handover, which will reduce this figure to 537. The latest documents suggest Circuit Switched 64kbps (CS64) and Packet Switched 64/64 kbps (PS64/64) uses 2 CE in the uplink (UL) and downlink (DL). Packet Swit ched 64/384 kbps (PS64/384 - 64 kbps in the UL and 384 kbps in the DL) will use 2 CEs in the UL and 8 CEs in the DL. Air Interface Capacity This is a much more complicated issue that is dependent on many factors, for exa mple, uplink interference, downlink power, location of the Mobiles etc. In fact, it is hard to think of something that does not influence this! There are various formulae to calculate the theoretical maximum number of simult aneous connections possible (Mpole or Mmax). The result will be dependent on the service data rate. For example, typical figures for voice are approximately 100 . This amount of connections would represent a 100% load on the Node B, which is not practical. The best place to look for practical values is in an operation W CDMA network. To the best of my knowledge there are two (non-trial) WCDMA networks in the worl d, NTT DoCoMo in Japan and Manx Telecom in the Isle of Man-although I am not ent irely convinced this is not a trial system. Since neither is using an exclusive Ericsson Radio Access Network, they might not be willing to release this informa tion to us! For this reason, I suggest looking at Qualcomm s IS-95 network, which has strong s imilarities to the WCDMA Air Interface. They quote in the region of 18 simultane ous connections (just one service is available voice) per RF carrier. Since the bandwidth of WCDMA is approximately three times that of IS-95, I imaging WCDMA c ould support (18X3) 54 simultaneous voice connections. The latest RBS3000 can support a maximum of six RF carriers configured as a thre e-sector site. The total Node B capacity would therefore be (54 x 6) 324. This i s well within the Channel Element limit, even with soft handover. Again, the service rate will have an impact on this. To simplify this the load g enerated by each service is equated to speech using units called Air Interface S peech Equivalents (ASEs). The latest figures I have available for these are: ? CS 64 uses 4 in the UL and DL. ? PS 64/64 uses 2.16 in the downlink and 0.3 in the uplink* ? PS 64/384 uses 2.19 in the uplink and 0.3 in the downlink*

* The values for the packet services are low because the activity factor is take n into account. Eddie Mc Connell

Edited: 2006-06-22 11:33 by Arshad Abbasinezhad View Properties

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Hi, The traffic in a 3G RBS is dependent on RBSs´ output power, amount of channel elem ents (HW), interference in the channel and how the users are distributed in the cell. All this terms are dependent of each others as well. Some examples: 1. If we have a base station with high power it means more power in the air result ing more interference for neighbor cells. 2. If most of users are at the cell border this means they need more power to se nd with, that results more interference for neighbor cells and less power left f or new users in own cell. 3. If a cell has too much traffic this means more interference for neighbor cell s resulting less available capacity in the neighbor cells. 4. Different users need different amount of resources (speech, 64 kbps, 128 kbps , 384 kbps). All these show that Design and cell planning of the network is very important fo r the traffic handled by the cell. After all if you know your load limit (ex. 60% in down link) and you know your u sed services then you can calculate your theoretical capacity for one carrier by the formula (Please see guidelines): Loading = (M1/Mpole,1) + (M2/Mpole,2) + (M3/Mpole,3) + ... Arshad

Edited: 2006-06-22 11:33 by Andrea Di Rocco View Properties

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As everybody pointed out, the CE is one limitation of the traffic. CE dimention ing guideline will tell you what to use for that. For air interface capacity, the main problems are interference and power setting . Guideline 6, RF formula will give you the latest numbers for Mpole. Mpole in tur n will tell you what is expected base on typical interference. If you need the i nformation for RFQ purpose, use that value, discounted with your expected loadin g 1- You actual capacity will vary from RBS to RBS based on the quality of the net work (sites that can be used) and the amount of optimization. On average you sho ul be able to achieve the Mpole * loading, but with large variation.

2- An other aspect to consider for DL capacity, is the power setting. With more MCPA power, but same common channel, you can increase the capacity of 1 cell. yo u cannot increase the capacity of all cell that way, as the increase interferenc e will kill any gain that you could expect. Per TCh is also important, as if you assign less power per user, you will be able to admit more user (assuming that some will reach the max). For information, on an IS-95 system, in a control envi ronment, without interference, I change the DL capacity from around 30 to more t han 40 simultaneous user only by changing the min power level (in this case, min imum power level had to be set as IS-95 DL power control is limited) An additional question that come to mind is how HO will affect capacity? From an air interface perspective, the impact will be large, as lots of HO usually mean that the network is not fully optimized (or is not operating at the load it is optimize for). From a parameter setting point of view, if you try to limit the A ctive set to reduce the HO, the impact will be minimum or actually decrease your capacity. The reason for that being that increasing the active set, allow more HO, which increase you HO gain, decrease the require Tx power (TCH) per user. Christophe

Edited: 2006-06-22 11:33 by Anders Wannstrom View Properties

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The traffic the RBS can carry is in principle limited by the number of channel elements available. However, for practical dimensioning you need to take blockin g probabilities and traffix mixture into account. Also, the traffic is more like ly to be limited by the air interface rather than the hardware configuration (if properly dimensioned). In that scenario you therefore need to specify all relev ant parameters such as traffic mix, blocking probabilities planned for, channel models, maximum load planned for etc.

al - check alarms cabx - check board status lt all ; kget - take a parameter dump lgo - view parameter change log cabr - view all board restarts cvls - list of CVs on node including loaded / executing hc - health check (includes all error logs)

How to see vswr, output power etc in the Cell Log on to the NodeB by using telnet or hyper terminal and follow the comma nds bellow.

Note, We will here log on to the TMA/ASC.

``To exit the process write exit``

lhsh 010600 (AIU) is for Cell 1 lhsh 010900 is for Cell 2 lhsh 011200 is for Cell 3

1:

$ lhsh 010600 Welcome to OSE Shell OSE4.4.1.

2: 010600> ps port* pid name

tpr block

own status

000300eb port_0_dev_17/ose_sh ph CXC1323891%1_R14

0 -

000100e4 port_0_dev_17/tmaCdc ph CXC1323891%1_R14

0 -

000100e3 port_0_dev_17/tmaSbc ph CXC1323891%1_R14

0 -

000200e1 port_0_dev_17/XcbcSe ph CXC1323891%1_R14

0 -

Total 4 processes

3: 010600> lhsh port_0_dev_17 Welcome to OSE Shell OSE4.4.3. port_0_dev_17> We are now logged to the TMA/ASC. To see the measurement wri te: asc vswr

010600> lhsh port_0_dev_17 Welcome to OSE Shell OSE4.4.3. port_0_dev_17> asc vswr

Could not obtain name of terminal.

Branch:A, VSWR:1.27 (fwdVoltage:3.32V reflVoltage:2.41V fwdPower:29.08dBm re flPo wer:10.63dBm) Branch:B, VSWR:-12.73 (fwdVoltage:1.46V reflVoltage:1.44V fwdPower:-5.68dBm refl Power:-4.32dBm) port_0_dev_17>

Note: This is a normal output from a NodeB

4: If you want to see all the commands for the asc write like bellow.

port_0_dev_17> asc help Could not obtain name of terminal. ASC INTERNAL TEST COMMANDS

Syntax: asc



Description

--------- -----------

-----------

help

This text.

asc selftest

ASC selftest

asc vswr

measure vswr both branches

asc rl anches

measure return loss both br

asc pow h branches

measure TX output power bot

asc intpow atus

measure internal voltage st

asc extpow

measure external (RET) volt

age asc lnatemp

measure LNA board temperatu

re asc dpbtemp oard (AUM) temperature

measure Device Peripheral B

asc lnaerrset lt, single, both or no transistor, branch [a|b]

simulate LNA transistor fau

asc lnaerr error fault status

read current LNA transistor

asc hwerrset 0|1 /set [0|1] (fault detected at self/startup test)

General HW error SBCI reset

asc pset_dpb set TMAU_TEMP_LIMITS (DP Bo ard) temp. parameters asc pset_lna set TMA_LNA_TEMP_LIMITS (LN A Board) temp. parameters asc pset_ext and max supply) voltage parameters asc gaincal ta (0-255) in position

set TMAU_EXT_POW_LIMIT (min set RAM gain calibration da

With RBS3206 type Hardware use the following command:

Fui get vswr

// get instead of asc

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Posted: 2007-12-11 22:28 by GUILHERME PUPIO View Properties

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