Tao Xiaofeng

A Spatial Multiplexing MIMO Scheme with Beamforming for Downlink Transmission

This paper investigates a spatial multiplexing MIMO scheme with beamforming for downlink transmission. The proposed scheme combines spatial multiplexing MIMO technique with beamforming, which has the advantages of both techniques. The proposed scheme utilizes the uplink direction of arrival (DOA) to perform downlink beamforming. It is able to transmit parallel data streams as well as providing beamforming gain and improve the system performance significantly. The proposed scheme provides better BER performance than the traditional spatial multiplexing and beamforming techniques under the same simulation environment.

A 223Mbps FPGA Implementation of (10240, 5120) Irregular Structured Low Density Parity Check Decoder

This paper presents a high speed decoder architecture for irregular structured low density parity check (LDPC) codes and its field programmable gate array (FPGA) implementation. Algorithm transformation and architectural level optimizations are employed to reduce the critical path. The enhanced semi-parallel architecture is easily scalable and reconfigurable for larger block sizes and can be well suited for achieving high decoding throughput. Based on the proposed architecture, a (10240, 5120) irregular structured LDPC decoder is implemented on Xilinx FPGA Virtex-4 VLX80, the FPGA implementation results show that the irregular LDPC decoder can achieve a maximum (information data) decoding throughput of 223 Mbps at 18 iterations.

A Believable Factor and Kalman Filtering Based Mobile Localization Algorithm

One of important issues that deteriorate the accuracy of location is the non line of sight (NLOS) problem. This paper proposes an efficient NLOS mitigation algorithm based on Kalman filtering and believable factor to enhance the accuracy of localization. Simulation results show the proposed method can mitigate NLOS errors effectively and improve the localization accuracy in NLOS environment.

Low Complexity Hardware Implementation of V-BLAST Receiver

This paper presents a simplified V-BLAST (vertical bell lab layered spaced-time) detection algorithm from the hardware implement perspective. Simulation shows that the BER (Bit Error Rate) performance is close to Golden detection algorithm, but the complexity is greatly less. Then the paper provides an efficient hardware structure to implement this algorithm in FPGA (field programmable gate array), which can be used in the B3G TDD-MIMO-OFDM (Beyond 3G Time-Duplex-Division Multi-Input Multi-Output Orthogonal frequency division multiplexing) system. By applying bit-width reduction technique, the fabrication area it takes can be significantly reduced. In uplink, we adopted 4 transmit and 8 receive antennas. The implementation with Virtex square Pro Series FPGA was verified to be worked well in B3G system.

Interference coordination for secrecy enhancement in random wireless networks

The co-channel interference modeling is vital for evaluating the secrecy performance in random wireless networks, where the legitimate nodes and eavesdroppers are randomly distributed. In this paper, a new interference model is proposed from the user-dominant perspective. The model can provide a better analytical assessment of secrecy performance with interference coordination for the presence of eavesdroppers. The typical legitimate is assumed to be located at the origin, and chooses the closest base station (BS) as its serving BS. The field of interferers is obtained by excluding the desired BSs (including the serving BS and its cooperative BS(s)). In contract with the exiting interference model, it is assumed that desired BSs and interferers belong to the same Poisson Point Process (PPP), and eavesdroppers are distributed according to another independent PPP. Based on this model, the average secrecy transmission capacity is derived in simply analytical forms with interference coordination. Analysis and simulation results show that the secrecy performance can be significantly enhanced by exploiting interference coordination. Furthermore, the average secrecy transmission capacity increases with increasing number of cooperative BSs.

Data Broadcast Scheduling in Broadcast/UMTS Integrated Systems Using Mathematical Modeling and Computing Techniques

Wireless broadcast systems provide the users with high bandwidth while 3G cellular systems provide complementary service to support personality and interactivity. In this paper, we develop a novel scheduling algorithm for the integrated Wireless Broadcast/3G system. The proposed algorithm combines Analytic hierarchy process (AHP) and Grey relational analysis (GRA). Simulation results are presented to demonstrate that the proposed algorithm could effectively support data dissemination with low response time, request drop rate, and the unfairness of request drop.

Generalized Distributed Multi-antenna Architecture Based Location Technology for Beyond 3G Systems

In order to research mobile terminal location technology for the next generation mobile communications, this paper sums up existing location technology of current mobile communications system, and then introduces generalized distributed antenna network architecture for beyond 3G system. On this basis, this paper presents a novel mobile terminal location technology. This method is based on the multi-antenna architecture, which calculates the distance between each antenna and mobile terminal by link gain, then locates the position of mobile terminal, or its probability in this region. The simulation result and error analysis confirm that this method can provide a location technology with higher precision than other location technologies in current mobile communication system.

A Distributed Multi-Antenna Based NLOS Error Elimination Algorithm for Mobile Localization

An important problem in wireless location systems especially in urban environment is the non-line-of-sight (NOLS) error. In this paper, we propose a novel NLOS error elimination algorithm based on distributed multi-antenna in time-of-arrival (TOA) location estimation. One important conclusion can be drawn by analyzing different scattering models: NLOS errors contained in TOA estimates which are measured by different antennas in one multi-antenna array have great correlation. We process these TOA measurements to estimate the position of scatterers which cause the NLOS propagation and to calculate NLOS errors contained in TOA measurements. Simulation results show that this algorithm can eliminate NLOS error effectively and improve the accuracy of TOA location algorithms in NLOS environments significantly.