Relay positioning for energy saving in cooperative networks

The number of Access Points (AP) in a network is much smaller than the network users. Hence, some users may be far from Aps requiring more power to transmit data. Cooperative communication has been proposed, which uses the broadcast nature of the wireless medium to exploit the spatial diversity in wireless networks. Users in cooperative communication system work cooperatively by relaying the packets through a relay node(RN). One issue is to find an near optimal positions for the limited number of available relays to reduce energy consumption of the users. In this paper, we investigate the position of the relays and its effect on energy saving in cooperative wireless networks. Initially, we use a greedy algorithm to determine the position of the relays and determine the energy saving achieved from this algorithm. Then, we use our improved iterative algorithm to place the relays. Using simulations, we compare both the algorithms in terms of average energy consumption, average number of hops and average r-cover (RNs form an r-cover if each user is within distance at most r from the RN). It is evident from the simulation results that the improved algorithm outperforms the greedy algorithm in all the above mentioned aspects. The results provide us an insight into positioning of the relays in a cooperative wireless network to reduce energy consumption of the users.