Supervisor: Prof. Jyri Hämäläinen Instructor: M.Sc Zhong Zheng A part of NETS2020 project Ying Yang

Outline Introduction and motivation Femtocell challenges and problem statement Research approach & Assessment methodology LTE Fractional Power Control (FPC) Stochastic Frequency Domain Scheduler (SFDS) Simulation results Conclusion 18/05/20112

Introduction & Motivation 3GPP LTE project aiming to achieve a high quality of services in packet switching optimized system with higher data rates and cheaper infrastructure. - (3G UMTS ↑5.8↓14 LTE↑50↓100 Mbps ) 3G network drawback – Indoor coverage shortage  Femtocell can solve this bottleneck and fulfill the requirement of LTE development - Small BS with limited power and coverage area - Suitable for indoor communication environment - Decrease macrocell traffic load dramatically (50% call, 70%SMS takes place indoor) and provide higher data rate by direct connecting to Internet through broadband or DSL 18/05/20113

Femtocell Challenges & Problem Statement Interference to existing macro cells - Inter-macro-femtocell interference suppression Interference between femtocells Integration to LTE core network Marketing and product promotion Service stability Price attraction 18/05/20114

Research Approach & Assessment methodology Adjust FUE PC parameters and find an optimal set to compensate interference from neighboring MUEs while keeping minimum degradation of MUE performance Apply a simple distributed frequency-domain scheduling strategy (SFDS) in FBS to roughly separate macro and femto spectrum in a probabilistic manner 18/05/ User Throughput – The total throughput per PRB for FUE and/or MUE in bps. All the user throughputs are considered in link level. -X%-tile User Throughput – The throughput at the X%-tile point of the Cumulative Distribution Function (CDF) of the user throughput in bps, which is the key indicator for coverage and capacity performance -User SINR and Transmission Power – The experienced SINR and distributions of FUE/MUE total transmission power in dBm -Spectral Efficiency – The data transmission rate for FUE/MUE normalized by the transmission bandwidth in bps/Hz

LTE Fractional Power Control (FPC) 18/05/20116

LTE FPC Cont. 18/05/20117

Stochastic Frequency-Domain Scheduler (SFDS) 18/05/20118

SFDS Cont. 18/05/20119

Simulation Scenario 18/05/201110

Simulation Parameters 18/05/ System Parameters Carrier Frequency2 GHz Inter-site Distance500m (3GPP Case 1) Bandwidth10 MHz, 48 PRBs for data, + 2 PRBs for signaling Thermal Noise PSD-174 dBm/Hz Shadowing Shadow Fading Log-normal Standard Deviation 4 dB (FBS-serving UE), 8 dB (other links) Correlation Factor 0.5 between sites 1 between sectors MBS Parameters Maximum Transmit Power 46 dBm Maximum Antenna Gain 14 dBi Noise Figure 7 dB Antenna Pattern: where =25dB, =70 degrees FBS Parameters Maximum Transmit Power 20 dBm Noise Figure 7 dB Antenna Pattern Omni-directional UE Parameters Maximum Transmit Power 23 dBm Maximum Antenna Gain 0 dBi

Channel Models 18/05/201112

Optimal FUE PC parameters 18/05/201113

UL Scheduling Gain with SFDS 18/05/ ‘O’:= 4; ‘ △ ’: =24; ‘ ▽ ’: =48

UL Scheduling Gain with SFDS 18/05/ ‘O’:= 4; ‘ △ ’: =24; ‘ ▽ ’: =48

FUE total transmission power comparison with 3 different settings: 18/05/201116

DL Scheduling Gain 18/05/ Solid curves: Fast signaling Dashed curves: Slow signaling 50%-tile UE spectral efficiency by SFDS with fast and slow signaling

Conclusion An optimal PC configurations for FBS is found by simulation which maximizes the FUE link quality while keeping minimum degradation to nearby MUEs SFDS can roughly separates the spectrum usage for FUEs and MUEs in a probabilistic manner by performing biased resource selection in different part of the allocated spectrum, simulation results show significant performance gain when femtocell has low or moderate load 18/05/201118

THANK YOU! Questions? 18/05/201119

References [1] C. U. Castellanos, D. L. Villa, C. Rosa, K. I. Pedersen, F. D.Calabrese, P. H. Michaelsen, and J. Michel, “Performance of uplink fractional power control in UTRAN LTE,” in Proceedings of the IEEE Vehicular Technology Conference VTC ′ 08, pp , May [2] 3GPP, TR , “Mobility procedures for Home Nod B(HNB), Overall description, Stage 2”, V9.4.0, June /05/201120