unit variance. The channel gains are $g_{ij} = |h_{ij}|^2$ and exponentially distributed, taking values in the range $(0,1]$. The power level chosen by the transmitter $i$ is denoted by $P_{i}$. $n_{i}$ denotes the variance of thermal noise at the receiver $i$, which is assumed to be AWGN.

Since we implement successive relaying, we (may) have concurrent transmissions by the source and one relay taking place at the same time slot. This results in IRI and the source has to consider the interference power that the candidate relay for reception will receive by the transmitting relay.

![The system model: Source $S$ communicates with Destination $D$ via a cluster of relays $R_k \in \mathcal{C}$, $k\in[1,K]$.[]{data-label="overflow"}](Figures/relay_net){width="0.45\columnwidth"}

It is worth noting that our focus is to investigate the performance of a new buffer-aided successive opportunistic relay selection scheme under a global Channel State Information (CSI) assumption and hence, the implementation issues are beyond the scope of this work. Note, however, that conventional centralized/distributed half-duplex relay selection approaches can be applied for the implementation of the proposed scheme (e.g., [@BLE1; @NOS; @SHAH]).

The interference power at the $k$-[th]{} receiver, $I_{k}$, in its general case, includes the interference from all the transmitters (belonging in a set 