A Cross-layer Relay Selection Algorithm for Infrastructure-Based Two-hop Relay Networks

Abstract

Relay selection is a key issue in multihop relay networks. This paper proposes a cross-layer design relay selection algorithm for the infrastructure-based two-hop relay networks by introducing a novel utility function as the relay selection criterion. The proposed algorithm considers both channel state information(CSI) at physical layer and queue state informance(QSI) at data link layer, the goal is to guarantee the diverse QoS requirements for different services.Simulation results show that the proposed algorithm can decrease packet transmission time delay and packet dropping probability significantly while make a slight penalty on system spectrum efficiency. Moreover, it can exploit multiuser diversity gain.

A distributed cross-layer relay selection with fairness consideration based on buffer management

“…In Step 1, computational complexity due to (8) contains Ns-1 additions, Ns divisions, and Ns*Nr multiplications.…”

“…The first one [5] is Spectrum Efficiency-based Best Relay Selection (SE-BRS) algorithm in which each user selects the relay that results in the maximum spectrum efficiency without considering any cross-layer parameter. The second one [8] is Spectrum Efficiency and QSIbased Best Relay Selection (SE-QSI-BRS) algorithm in which the relay selection is done iteratively. In this algorithm, each user with a large data rate is capable of capturing the whole free buffer space of its selected relay which violates fairness among the users as mentioned in Section I.…”

“…In the second step, each user selects the best relay for cooperation according to a novel utility function which is based on both spectrum efficiencies resulted from using different relays, calculated in (7), and the buffer space shares specified in (8). The novel utility function for the i-th user using the j-th relay is…”

“…In cooperative networks, waiting time in buffer queues is the main cause of the transmission time delay and drop of the packets will happen in the case of facing a full buffer. Recently, some work has been done on cross-layer relay selection [6]- [8]. In [6], QoS is not assumed to be affected by the limitation of the buffer space of relays.…”

“…In [7], where the limitation of buffers is considered as a criterion, the system is assumed to be single user. In [8], a utility-based relay selection method is proposed for a multi-user cooperative network, considering both channel state information (CSI) and buffers' queue state information (QSI). However, it dedicates the whole buffer of each relay node to just a single user at a time.…”