Lianhai Shan

Predictive Group Handover Scheme with Channel Borrowing for Mobile Relay Systems

Broadband wireless communication systems should be able to support users moving at high speeds. Groups of users in large vehicles moving along approximate straight ways usually need to perform handovers more frequently, and this drastically increases system overhead. Conventional handover methods cannot promise a good enough handover success rate for multiservice group mobility. The different service connections with group mobility require an adequate handover scheme to guarantee the quality of service. In this paper, we present a new handover scheme called predictive group handover with channel borrowing for groups of user using a mobile relay station installed in large vehicle such as a bus or light rail. The proposed scheme makes use of location and direction information to predict the target base station and pre-notify this base station about the user connection information in order to reduce the connection blocking probability and handover dropping probability efficaciously. The simulation results closely match the results of the system analysis.

Relay Enhanced Architecture for Broadband Wireless Access Networks

Services based on the broadband wireless access (BWA) technology are fast developing, yet the applications are limited by the radio spectrum resource. Due to the high frequency bands allocated, the conventional cellular (single-hop) BWA network can not promise both coverage and throughput achievements in the metropolitan environment This paper proposes a MAC layer simulator architecture introducing cross-layer design to enhance the radio resource management in the BWA networks. Then relay concept is transferred into the BWA networks where relay station (RS) pads the shadowing area between directional antennas. The results show that the proposed relay enhanced BWA system outperforms the single-hop one on both spectrum efficiency and throughput.

FRS Handover for Multi-Hop Relay Network Based on Load Balancing Combining Resource Reallocation

A fixed relay station (FRS) handover strategy based on load balancing combining resource reallocation is proposed for multi-hop relay network in this paper. FRS located at the edge of cell will be reconnected to neighbor cold cell conditionally for balancing current hot cells load. At the same time, wireless channel resources reallocation algorism will be used to provide resources as much as possible for FRS handover and to guarantee FRS handover quality. Based on FRS handover process, we propose an FRS handover analysis model. The simulation result shows that proposed method could decrease new call blocking probability and handover call dropping probability of hot cell effectively in the case of ensuring FRS handover success probability.

Dynamic Nodes Selection Based Cooperative Frequency Offset Estimation Algorithm

Due to great carrier frequency deviation under high speed railway environment (HSRE), the existing estimation algorithms perform ineffectively in terms of complexity and the estimation accuracy. In this paper, dynamic nodes selection strategy is proposed to achieve diversity gains in cooperative frequency offset estimation. This paper presents a weighted frequency offset estimation model for each receiver. The model not only allows for the weight of SINR but includes the weight of strong path signal. Monte-Carlo method is used to simulate the HSRE OFDM system. And numerical results of cooperation model are compared with conventional algorithms. Both of which verify that the cooperative estimation method is closer to the lower bound and shows better system performance in terms of bit error rate.