Conventional abstraction models of physical-layer algorithms have been proven inaccurate for the cross-layer design of wireless networks with cooperative relaying diversity. To partially fill this gap, this paper proposes an enhanced packet reception model to assist in the cross-layer design of physical and link-layer algorithms with cooperative relaying diversity. The analysis is mainly focused on algorithms where relaying-phases are activated whenever a packet error is detected in previous transmissions. A simplification of this model is proposed by assuming that correct reception is achieved whenever the instantaneous signal-to-interference-plus-noise ratio (SINR) surpasses a given threshold. By further assuming operation in Rayleigh channels, reception probabilities are derived in useful closed-form expressions. This novel result is then used to confirm that cooperative diversity in multi-cell environments with fixed and distributed relays considerably outperforms conventional approaches in terms of throughput and power consumption, particularly for users located near the nodes and at the edge of the cell. Finally, average delay is evaluated using an M/G/1 queue model which shows that relaying phases have a minor but finite impact on the waiting time of each user.