Peng Mu-gen

Performance Analysis and Improvement of HARQ Techniques in TDD-HSDPA/SA System

HSDPA proposed in 3GPP is the best evolution of current UMTS to support high data rate services. It adopts numbers of enhanced techniques including AMC, HARQ, fat-pipe scheduling etc. This paper investigates the performance of different HARQ schemes considered for TDD-HSDPA system on system level. Special address is put on the affect of smart antennas. A kind of improved full IR is also proposed and investigated

A blind signal detection scheme for co-channel interference cooperative systems

The co-channel interference exists in the uplink multiuser multi-relay cooperative systems. In order to deal with it, a blind signal detection scheme based on parallel factor (PARAFAC) model is proposed in a Co-Channel Interference DS-CDMA cooperative system. A trilinear alternating least squares (TALS) algorithm is applied in the PARAFAC model. The feasibility of this proposed scheme and the data range of each parameter are analyzed. Compared with constant-modulus (CM) blind detection algorithm, this proposed scheme has stable fitting result, as well as better detection performance in channel and signal estimation. Simulation results corroborate the effectiveness of our scheme in terms of channel estimation accuracy and biterror-rate.

An enhanced algorithm for the transmission mode switching in TD-LTE downlink systems

Downlink beamforming is an efficient technique in TD-LTE systems to provide the diversity or multiplexing gains when suitable antenna mode switching algorithm is applied. Since the radio channel information is not perfectly obtained at the transmitter, the antenna mode decided by the base station (BS) is not often suitable, and the cell throughput decreases especially when the user equipment (UE) with high speed mobility and there is a large feedback delay. To solve this problem, a dynamic antenna mode switching (DAMS) algorithm is proposed for the downlink transmission in TD-LTE systems, where a cell-specific offset and a UE-specific offset are utilized to adjust the channel quality indicator (CQI) fed back from UE and determine the suitable antenna mode. According to the simulation results, compared with the conventional mode switching (CMS) algorithm, the proposed DAMS algorithm enhances both the cell spectrum efficiency and the initial transmission success ratio (ITSR) dramatically.Downlink beamforming is an efficient technique in TD-LTE systems to provide the diversity or multiplexing gains when suitable antenna mode switching algorithm is applied. Since the radio channel information is not perfectly obtained at the transmitter, the antenna mode decided by the base station (BS) is not often suitable, and the cell throughput decreases especially when the user equipment (UE) with high speed mobility and there is a large feedback delay. To solve this problem, a dynamic antenna mode switching (DAMS) algorithm is proposed for the downlink transmission in TD-LTE systems, where a cell-specific offset and a UE-specific offset are utilized to adjust the channel quality indicator (CQI) fed back from UE and determine the suitable antenna mode. According to the simulation results, compared with the conventional mode switching (CMS) algorithm, the proposed DAMS algorithm enhances both the cell spectrum efficiency and the initial transmission success ratio (ITSR) dramatically.

Capacity Evaluation of Cellular TDD-CDMA Systems Deploying Multi-frequency

Both uplink and downlink capacity of cellular time duplex division-code division multiple access (TDD-CDMA) systems deploying multi-frequency are analyzed theoretically. The impact of multi-user detection, inter-frequency interference and different traffic types on multi-frequency TDD-CDMA system capacity are discussed. Simulation is done to evaluate the theoretical analysis and a good concordance is observed. Simulation and theoretical results show that adjacent channel leakage ratio should at least 10 dB to achieve higher capacity by deploying multi-frequency. When adjacent channel leakage ratio is bigger than 30 dB, the capacity of N frequency system is exact N times that of single frequency system. The conclusions are true for both uplink and downlink.