Delay Optimization on a p-Persistent MAC Protocol for a Multi-Packet Detection in SC-FDE System

Abstract

This paper deals with multi-packet detection for SC modulations (Single-Carrier) with FDE (FrequencyDomain Equalization). We consider iterative frequencydomain receivers that jointly perform equalization, multipacket separation and channel decoding operations, for up to Q max mobile terminals transmitting in one slot.In this paper we propose an accurate analytical model for a p-persistent random access MAC protocol, designed to handle a total number of mobile terminals J above Q max . It evaluates the uplink non-saturated packet delay and calculates the optimal configuration for the packet transmission probability associated to each mobile terminal that minimizes the delay. Our analytical results are validated using physical and MAC layer simulations. 1

Frequency-domain cross-layer diversity techniques: an efficient way of coping with lost packets in broadband wireless systems

“…A promising NDMA scheme for SC-FDE systems is presented in [13], which allows an efficient packet separation. As with DC schemes, the receiver reduces the PER since it combines the signals associated to all Q transmissions.…”

“…However, we need to know the number of users involved in a collision (Q) and which ones are they. This information can be obtained by transmitting suitable training blocks (quasi orthogonal for different users) before the data blocks [13].…”

“…The MAC layer helps to control this aspect and all the mechanics of the retransmissions (see below and [13]). Figure 2 illustrates the frequency-domain multi-packet receiver able to separate up to Qmax packets involved in a collision using the NDMA scheme [4,13]. It is an iterative receiver that jointly performs the equalization and multipacket detection procedures, where each iteration consists of Q detection stages, one for each packet.…”

“…These mechanisms were proposed for scenarios where MTs contend to access the medium with parallel and simultaneous transmissions. [13]. It is assumed that packets arrive simultaneously and a perfect power control and time advance mechanisms exist, able to compensate different propagation times and attenuations.…”

Minimum Delay Routing in Multihop Wireless Networks

“…The optimization problem was solved by using dynamic programming formulation, from which a closed form expression for the optimal sleep duration is derived. Pereira et al [4] addressed delay optimization problem for a random access MAC protocol. They presented an accurate analytical model to derive the optimal transmission probability of each mobile node that minimizes the delay.…”