1 Uplink Resource Allocation in LTE-A Relay Enhanced Cellular Networks Master’s Thesis Seminar Presented by: Anzil Abdul Rasheed Master’s Program – Radio Communications Thesis Supervisor: Prof. Jyri Hämäläinen

2 Contents of the Presentation  LTE Features  LTE-A Relaying  Simulation Parameters  Resource Allocation Methodologies  Performance Analysis CDFs SINR Throughput Inter-Cell Interference Coordination End-to-End Throughput UE Transmit Power  Conclusions

3 LTE Features  Support for scalable bandwidth 1.25, 1.6, 2.5, 5, 10, 15 and 20 MHz  Improved data rates For a 20 MHz spectrum allocation  UL – 50 Mbps, DL – 100 Mbps  Support for mobility upto 350 km/h  All IP-based flat network architecture  Reduced latency  Reduced operator maintenance costs  Multi-layer security  OFDMA & SC-FDMA based transmission scheme Reduced interference Robust to multipath

4 LTE-A Relaying  DF RNs are foreseen as one of the means to satisfy the performance targets of 4G networks as defined by ITU-R  Advantages: Improved radio quality in shadowed/high path-loss regions Easier upgrade from current deployments Self backhauling  Reduced costs in data tunneling (ref. HeNB)  Improved security (independence) Reduced CAPEX/OPEX  Challenges: Maintain simple architecture Interference related issues from a new RAP Multihop transmission delays Resource allocation

5 Simulation Parameters

6 Resource Allocation Methodologies  Full Reuse, Isolated Reuse, Grouped Reuse Reuse 1 at RN Reuse 3 at RN  Grouped Reuse (GR): GR/R1 GR/R3

7 CDF of SINR per PRB eNB Full Reuse increases interference Isolated Reuse prevents interference between the direct and access links  Throughput gain needs to be seen! Grouped Reuse performs well and improves SINR over the eNB-only deployment  Interference from access link transmissions is under control RN SINR improvement in all cases as expected Reuse 3 is beneficial (as expected) for reducing interference among RNs  Indirect benefit in the form of reduced interference at eNB (for FR and GR)

8 CDF of Throughput per UE FR and IR do not improve throughput of all UEs GR translates to improved throughput Gains from complete resource allocation for eNB GR performs the best

9 Inter-Cell Interference Coordination with Grouped Reuse Reduced interference

10 End-to-End Throughput per UE  GR/R3 based E2E Resource Allocation in RECs  - Relay link is an overhead in REC system design With well-coordinated resource allocation such as GR/R3, REC can outperform conventional eNB-only system

11 UE Transmit Power Significant UE battery savings with GR/R3 REC

12 Conclusions  Resource allocation is a critical factor in improving the multi-hop performance  GR/R3 is an efficient resource allocation methodology Achieves interference coordination High spectral efficiency  The relay link is a bottleneck in system design Resource allocation for relay link is an issue with multiple RNs deployed per sector  Realizing performance gains with in-band RN deployment is challenging, but achievable with a well-designed transmission scheme and system parameter settings.  A UE operating in a REC (especially GR/R3 based) can experience significantly improved battery life.

13 Thank you! Questions? …