The Case for Carrier Aggregation Carrier Aggregation: Concepts, Drivers & Roadmap Network Deployment Options Overview of Carrier Aggregation in LTE-A Testing of Carrier Aggregation – Anritsu Solutions for LTE Carrier Aggregation • Conclusions and Q&A
Spectrum Congestion • Technology is reaching the limits of spectral efficiency (bps/Hz) • Ever increasing user demand (applications) requires more bandwidth • Few areas with large contiguous blocks of spectrum – Mainly at frequencies greater than 3GHz
• Available “prime” spectrum is fragmented in small blocks
Carrier Aggregation (CA) Concepts • Increasing RF and Baseband chipset integration opens the possibility to receive and transmit on more than one carrier simultaneously
CA Drivers • Intra-band Contiguous aggregation driven by >5 MHz 3G licenses and spectrum becoming available from WRC07 – Scale to wider bandwidths while
Multi-Carrier UE
still supporting existing UEs on a single CC
• Inter-band aggregation driven by existing licenses, mergers and acquisitions, and digital dividend – Piece together spectrum to compete with carriers having contiguous spectrum
LTE-A CA Overview • Uses R8/9 backward-compatible carriers as the basic building blocks • Signaling supports aggregation of up to 5 CCs in both UL and DL • One CC acts as the anchor (Primary) for mobility, others (Secondaries) are added/released through signaling on Primary • Supports Intra-band contiguous, non-contiguous, and Inter-band
• Supports use of Remote Radio Heads and Relay Nodes • Supports both symmetric and asymmetric aggregations Note: Although signaling supports up to 5 CCs, 3GPP Releases support specific configurations Release 10: In DL max 2 DL inter or intra-band contiguous or non-contiguous CCs, In UL max 2 intra-band contiguous CCs Release 11: In DL same as Rel10, In UL max 2 intra-band contiguous or non-contiguous CCs 21
Physical Layer Aspects of CA (2) • Downlink Radio Link Monitoring – UE evaluates Radio Link quality and failure through the Pcell – More effective to deploy Pcells as lower frequency in inter-band CA scenarios due to better propagation
• Timing and Synchronization – In the case of a co-located eNB, timing advance the same regardless of frequency (band)
• Cross-Carrier Scheduling – Decreases interference for HetNets – 3 Bit Carrier Indicator Field (CIF) Allows for Up to 7 Carriers
RRC Layer Aspects of CA (2) • SCell Addition and Removal – SCells cannot be added immediately at RRC establishment • Added and removed through RRC Connection Reconfiguration procedure
– Since intra-LTE handover is treated as RRC Connection Reconfiguration, CA “handover” is possible
• Handover Procedures for CA are Largely the same as Release 8 and 9 – New event A6 when neighbor PCell becomes larger than service SCell • Handover to neighbor Pcell depending on network conditions
Testing of Carrier Aggregation - High-Level Test Requirements • Potentially Large Numbers of Transmitters and Receivers – – – –
5 CCs with 8 x n MIMO with Handover => 80 Transmitters All may require independent up-conversion 5 CCs with n x 4 MIMO with Handover => 40 Receivers All may require independent down-conversion
• High Peak Data Rates – Up to 50K IP Packets/sec with some functions requiring processing per packet (e.g. ROHC) – e.g., Current solutions use 1Gbps Ethernet
• Logging – Tracing problems may require very smart search and filter tools – Logging at each layer can generate huge amounts of data
Testing of Carrier Aggregation • Development Testing – – – –
New L1 and L2 features New RRC signaling High rate bearers New connected mode mobility permutations
• Conformance Testing – New RF tests for each band combination – New RRM tests for new measurement types – New Protocol tests for L2 extensions and for R10 RRC signaling
• Carrier Acceptance Testing – Operator specific band combinations – Device performance
Conclusions • Huge growth in mobile data usage is driving demand for more network capacity – Carrier Aggregation provides a highly flexible solution with excellent re-use of existing standards and an easy route to provide backwards compatibility with legacy devices
• Carrier Aggregation Drives Complexity in both the Wireless Device and Base Station Simulator (Test Equipment) • Anritsu Supports the Evolution to Carrier Aggregation with a Parallel Portfolio of Both HSPA and LTE Capabilities
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