Miao Qingyu

MIMO Amplify-And-Forward Relaying: Spatial Gain and Filter Matrix Design

In this paper we investigate and analyze the performance of multi-antenna amplify-and-forward (AF) relays for a future cellular system where the destination and the source form a MIMO system. Two scenarios are analyzed, modelled and compared: the multi-relay scenario i.e. distributed relays, each equipped with at least one antenna; and the one-relay scenario i.e. a single relay in a sector where each relay is equipped with multiple antennas. The optimal filter coefficients applied at the relays are derived and recommended for both cases. The channel ergodic capacity and by product the throughput of the single link shows that the AF relay matched filter based performs best in the multi-relay scenario. On other hand the relay based singular value decomposition (SVD) is more suitable for the one-relay scenario.

Performance Comparison Between DF relay and RF Repeaters in the Cellular System

This paper compares the system level performance of Decode-and Forward (DF) relay and a RF repeater in a cellular system. The results show that for small cell sizes, the repeater system can bring higher cell spectrum efficiency gain than the relay system since repeaters in contrast to the relays are assumed to be able to receive and transmit at the same time. However, for larger cell sizes, the relay system can bring higher cell spectrum efficiency gain than the repeater system thanks to the possibility of simultaneous transmission by both the access point and relay node through employment of channel reuse. Irrespectively of cell size, simultaneous transmission by access point and relay node also implies that relays can provide higher system and user throughput than RF repeaters.

Coverage Study for VoIP over Enhanced Uplink

In this paper, the coverage of VoIP over enhanced uplink (EUL) is investigated and compared with the coverage of the traditional circuit switched AMR 12.2 kbps speech and 64 kbps data services. A propagation model is used to analyze the coverage for different cases. The coverage of EUL depends on a number of parameters, such as TTI length, number of retransmissions and relative channel power allocation. The simulations show better coverage for EUL using a TTI of 10 ms than 2 ms under comparable conditions, considering the same delay budget. Furthermore, in most of the cases the coverage of VoIP over EUL is comparable or even better than that of CS 64 kbps. VoIP over EUL has the potential to have a comparable or even better coverage than CS AMR 12.2 kbps if more power is allocated to EUL data channel and more transmission attempts are allowed