Joint relay‐pair selection for buffer‐aided successive opportunistic relaying

Abstract

In this work, we present a buffer-aided successive opportunistic relaying scheme that aims at improving the average capacity of the network when inter-relay interference arises between relays that are selected for simultaneous transmission and reception. We propose a relay selection policy that, by exploiting the benefits of buffering at the relays, decouples the receiving relay at the previous time slot to be the transmitting relay at the next slot. Furthermore, we impose an interference cancellation threshold allowing the relay that is selected for reception to decode and subtract the inter-relay interference. The proposed relaying scheme selects the relaying pair that maximises the average capacity of the relay network. Its performance is evaluated through simulations and comparisons with other state-of-the-art half-duplex and full-duplex relay selection schemes, in terms of outage probability, average capacity and average delay. The results reveal that a trade-off has to be made between improving the outage at the cost of reduced capacity and increased delay and vice versa. Finally, conclusions are drawn and future directions are discussed, including the need for a hybrid scheme incorporating both half-duplex and full-duplex characteristics.

Hybrid cooperation through full-duplex opportunistic relaying and max-link relay selection with transmit power adaptation

“…Note that in the case, for which at a slot the network operates in a single-link mode, CSI acquisition is triggered in the next slot. The selection process described by (8) assures that CSI acquisition is avoided as long as full-duplexity is achieved at a power cost which is not higher than Z. This scheme trades-off complexity reduction for performance degradation in terms of power reduction and allows the network to be configured in a variety of ways.…”

“…(8), Z can be split into two power levels, namely Z 1 and Z 2 (i.e., Z 1 + Z 2 = Z): one for the SR k link and one for the R k D link. For the R k D link, since there is no interference, the condition is fulfilled if P * Rj ≤ Z 2 .…”

“…In order to alleviate this loss, buffer-aided successive schemes have been proposed where two relays are concurrently activated, one for reception and the other for transmission, thus mimicking full-duplexity but at the cost of inter-relay interference (IRI). Works from this field include [7] where inter-relay interference was considered negligible and [8], [9] where IRI was mitigated to some extent through avoidance or cancellation. These studies have shown improved performance and the half-duplex loss has been recovered to a significant extend.…”

Energy‐efficient opportunistic forwarding in multi‐hop cellular networks using device‐to‐device communications

“…Simple schemes, where an SN stores and carries the information until favorable communication conditions with the destination node are found, have been shown to reduce energy consumption [11]. The studies reported in [12,13] also highlight the benefits of opportunistically exploiting the buffering capabilities at the relays to improve the average capacity and efficiency of the network. Opportunistic networking can also help offloading data traffic from cellular networks to metropolitan WiFi access points without degrading the QoS [14].…”

“…Equation (13) indicates that the PER augments with the distance (d in meters) between transmitter and receiver [despite using more robust modulation and coding schemes (12)], although an upper PER limit (0.75) is reached. The IEEE 802.11g channel efficiency (Eff ) represents the effective time that the 802.11g channel is used to transmit data, and depends on the transmission time of data packets .t d / and acknowledgement (ACK) packets .t ack /, the contention period .t cont / and the inter-frame guard times (DIFS and SIFS) [22]:…”