An Efficient Detection Technique for SC-FDE Systems with Multiple Packet Collisions

Usually, packets involved in a collision are lost, requiring the retransmission of all packets. However, if we do not discard collided packets and we use proper retransmissions we can efficiently resolve collisions. In this paper we propose a technique that allows an efficient packet separation in the presence of successive collisions. We consider an SC (Single-Carrier) modulation with FDE (Frequency-Domain Equalization) and we propose a frequency-domain multi-packet detection scheme. Since our technique requires uncorrelated channels for different retransmissions, we also propose a PS technique (Packet-Shift) for retransmissions using the same channel. Our technique allows high throughputs, since the total number of transmissions is equal to the number of packets involved in the collision. Moreover, the complexity is concentrated in the receiver, making this technique particularly appealing to the uplink of broadband wireless systems. By employing the PS scheme we can use the same channel for the retransmissions, with only a small performance degradation.