Coordinated Multipoint (CoMP) Transmission for LTE-Advanced Networks in Dense Informal Settlements
- 1. Coordinated Multipoint (CoMP) Transmission for LTE-Advanced Networks in Dense Informal Settlements Beneyam B. Haile, Edward Multafungwa and Jyri Hämäläinen Department of Communications and Networking School of Electrical Engineering, Aalto University Espoo Finland IEEE AFRICON 2013, Mauritius, September 11
- 2. Outline Ø Motivation Ø Deployment scenario Ø CoMP criteria and scheme Ø System simulation parameters and assumptions Ø Simulation results Ø Conclusion 2
- 3. Motivation (1/2) Future mobile networks are expected to deliver consistent throughput experience throughout the network 3 This is challenging in LTE networks due to varying desired signal strength, intercell interference and cross-tier interference across the network. CoMP technology is considered as a candidate solution and it has recently been studied by academia and industry. More challenging in dense informal settlement area
- 4. Motivation (2/2) CoMP performance is evaluated in 3GPP release 11 assuming ideal backhaul 4 An ongoing work item on evaluation of CoMP performance assuming practical backhaul is there in 3GPP release 12 Simulation works assume uniform cellular layout This study evaluates performance of a practical CoMP technique in an examplary dense informal settlement area considering terrain and 3D building information .
- 5. Deployment scenario in an example informal settlement area Three one-sectored macro cell deployed in Hanna Nasif area, Dar es Salaam, Tanzania 5 Hanna Nasif: around 40,000 people/km^2, 3000 buldings Users (LTE UEs) are dropped randomly in the simulation area. Note: Instead of users, we can also have hotspot nodes using CoMP as a backhaul
- 6. CoMP criteria and scheme 1(2) Coordination is assumed among the three macro cells 6
- 7. CoMP criteria and scheme 2(2) 7 CoMP UEs are selected based on the average of the difference between received signal powers from cell 1 and cell 2, and cell 1 and cell 3: CoMP technique: Quantized Co-phasing (QCP), suboptimal and practical (used in WCDMA/HSPA/LTE) Where
- 8. System simulation parameters and assumptions Parameter Values/Assumptions Air Interface LTE FDD Carrier Frequency 2000 MHz Simulation Radio propagation modeling (WinProp) Static system level simultion (Matlab) 5 m resolution; 1.5 m prediction height CoMP Three cooperating cells Downlink JP CoMP Q-CP limited feedback with N = 3 feedback bits Macro Cells Cell 1 Cell 2 Cell 3 Transmit Power 46 dBm 46 dBm 46 dBm Antenna Height 15 m 20 m 25 m Antenna Pattern Kathrein 741984 Kathrein 741984 Kathrein 741984 Azimuth 140 0 250 Intersite distance Approximately 500 m Mean UE Number 20 UE mobility Mobility off; Users distributed randomly in the simulation area in each snapshot Fading Shadow fading: Gaussian (0 dB mean, 8 dB standard deviation), decorrelation distance 50m Fast fading: Zero mean complex Gaussian Buildings Buildings of variable dimensions Building heights 3-6 m Building benetration loss: 10 dB 8 3GPP guidlines are used Average received power is computed using dominant path model implemented in the WinProp propagation modeling tool
- 9. SINR performance result (1/2) 9 CoMP threshold (dB) 1 3 6 10 0.5% 2.5% 15% 36% The higher the CoMP threshold the larger the number of CoMP UEs hence, the better the overall SINR performance Percentage of CoMP UEs One third of power transmission At low CoMP thresholds (≤ 3dB), the overall SINR performance improvement relative to non-CoMP case is negligible
- 10. SINR performance result (2/2) 10 CoMP threshold (dB) 1 3 6 10 0.5% 2.5% 15% 36% The difference in transmission powers has very little impact on overall SINR performance Percentage of CoMP UEs Full power transmission Most of the SINR gain is achieved from avoiding the interferences than the Q-CP transmission technique
- 11. SNR gain performance result 11 CoMP threshold (dB) 1 3 6 10 0.5% 2.5% 15% 36% The best SNR gain performance is achieved for the smallest threshold, thus smallest power imbalance Percentage of CoMP UEs Full power transmission Similar trends in SNR gains are noted through analytical studies
- 12. Spectral efficiency performance result (1/2) 12 Full power transmissionOne third of power transmission The larger the CoMP threshold, the higher the overall spectral efficiency gains
- 13. Spectral efficiency gain performance result (2/2) 13 Full power transmissionOne third of power transmission Energy efficiency gains are possible for one third power transmission without considerable reductions in spectral efficiency gains The smaller the CoMP threshold, the higher the CoMP UE spectral efficiency gains
- 14. Conclusions CoMP enhancements is a viable option for throughput enhancements in LTE networks that are being deployed in dense urban areas 14 The higher the threshold, the larger number of CoMP enabled UEs but smaller spectral efficiency gains for CoMP UEs Tradeoff between energy efficiency and spectral efficiency can be managed through optimal selection of transmission power of cooperating nodes. Future research: further study of energy-efficiency trade-off, CoMP in HetNets in densely populated area, CoMP as a backhaul of small cells and relays.
- 15. 15 Thank you for your kind attention! Further info: Beneyam Haile (Doctoral Researcher) and Edward Mutafungua (Post Doctoral Researcher) Aalto University School of Electrical Engineering Department of Communications and Networking Otakaari 5A, Espoo, Finland beneyam.haile@aalto.fi and edward.mutafungwa@aalto.fi Tel: +358 44 2108323 and +358 40 733 3397
- 17. Why Focus on Informal Settlements? • Focus of on informal settlements (slums) in suburban/urban areas – Emerging markets have fastest slum growth rates; 30-50% of global urban population in 2030 (UN HABITAT 2007) – Characterized by very high population density (>4000 people/sq km) and low income (1-3 USD/day) – Underserved: Limited access to key services (electricity, sanitation, healthcare, broadband etc.) Kibera, Nairobi, Kenya (pop. 230000 – 1 million, area 2.5 sq km) Korail, Dhaka, Bangladesh (pop. 120000, area 0.4 sq km)
- 18. Dominant path model • Dominant Path Model – Faster computation time than ray tracing models – Models dominant path between TX and RX pixel – More accurate than COST 231 model in scenarios with strong multipath propagation – Combination of urban and indoor predictions possible (CNP mode). • Urban Dominant Path Model (UDP) for outdoor • Indoor Dominant Path Model (IDP) with a higher resolution for indoor • Potentially good choice for urban or densely built suburban scenarios, particularly for cases with below rooftop transmitters (small cells) Comparison of different approaches (COST 231, Ray Tracing, DPM)
- 19. Average received power map