On the basis of the amplify-and-forward relaying mode, a two-hop distributed cooperative multi-relay system is proposed combining with the space-time block coding OFDM （STBC-OFDM） technique. Taking the maximum end-to-end data rate as optimization criterion, the signal-to-noise ratio （SNR） of receiving terminal is deduced. On the basis of the water-filling theory, the optimal power allocation （OPA） is achieved for each subcarrier in each antenna and each relay node （RN） of the two-hop, to realize the resource optimization. Monte Carlo method is adopted in simulation. The simulation results show that compared with the uniform resource allocation scheme, the proposed OPA strategy can.improve the system capacity. And the energy consumption of each transmission bit will be decreased, indicating the improvement of resource efficiency. In the scenario that the total power is limited, the system performance can be enhanced further by the distributed cooperative multi-relay through the diversity gain.
An architecture introducing wireless relaying technologies into the cellular infrastructure has emerged as an approuch to enlarge the coverage area and enhance system capacity. In this paper, a two-hop cellular system incorporated with the fixed Relaying Station （ RS） is studied, where besides the Uniform Power Allocation （UPA）, the Optimal Power Allocation （OPA） between the Base Station （BS） and RS is also adopted considering resource utilization. To marimize the performance gains and reduce the overhead, it is necessary to provide an effective RS selection algorithm and combine it with other resource management strategies. So two kinds of RS selection criteria based upon Signal to Interference Ratio （SIR） and PathLoss （PL）, are evolved into four Joint RS Selection and Power Allocation （JRSPA） algorithms, which are ba.cedon SIR with OPA （SIR OPA）, SIR with UPA （SIR UPA）, PL with OPA （PLOPA） and PL with UPA （PLUPA）. The simulation results show that among these four algorithms, the SIR OPA scheme provides the best capacity performance, but taking the overhead into account, the PLOPA scheme is a better choice to reduce the complexity and trade off the system performance with signaling load.
This paper proposes a Service Differentiated-Dynamic Slotted Multiple Access （SD-DSMA） protocol with QoS guarantee. The Media Access Control （MAC） frame format is variable according to the traffic of uplink and downlink and the traffic of control and data. In addition, the services are divided into two categories, Guaranteed Bandwidth （GB） and Best Effort （BE）. Uplink control message slots are designed for the GB users to reduce contention. Taking into consideration the techniques in physical layer, a two-Dimensional Radio Resource Allocation （2-D RRA） method is proposed. The 2-D RRA is an efficient way to allocate radio resources for multi-cell, multi-user OFDM/TDMA system as it takes into consideration both the channel condition and the co-channel interference. The piggyback mechanism and fair scheduling algorithm are adopted for GB services, and the max C/I scheduling algorithm is used for BE services. The simulation results show that the proposed MAC protocol has better performance in terms of delay, probability of successful access request.
