Network-assisted diversity for random access wireless networks

Abstract

A novel viewpoint to the collision resolution problem is introduced in this paper for wireless slotted random access networks. This viewpoint is based on signal separation principles borrowed from signal processing problems. The received collided packets are not discarded in this approach but are exploited to extract each individual user packet information. In particular, if users collide in a given time slot, they repeat their transmission for a total of times so that copies of the collided packets are received. Then, the receiver has to resolve a source mixing problem and separate each individual user. The proposed method does not introduce throughput penalties since it requires only slots to transmit colliding packets. Performance issues that are related to the implementation of the collision detection algorithm are studied in the paper. The protocol's parameters are optimized to maximize the system throughput.Index Terms-Collision resolution, diversity, Markov chain, M/G/1 queue, multiple access, random access, signal separation.

Collision Resolution Based on Independent Component Analysis

“…The reason is that both H and X being unknown, it can freely change the order of the terms in (1). So in the stage of user detection, ID sequences are needed to identify the users; Secondly, the sign of the separated signals may be changed, such as the information of user i changing from [1, -1, 1, -1] into [-1, 1, -1, 1] after the ICA processing.…”

“…In [1], Tsatsanis first proposed a scheme called network-assisted diversity multiple accesses (NDMA) which exploits network diversity to separate the collided packets. Subsequently some of improved schemes were proposed.…”

A Random Access Protocol with Multi-Packet Reception for Infrastructure-Less Wireless Autonomic Networks

“…Let us define the packet retransmission probability as the ratio of average unsuccessful packets using MPR to the average number of transmitted packets per time slot to the direction of a given mobile node Figure 2 shows the packet retransmission probability per time slot per node using Eq. technology described in [20], each mobile node can measure the network traffic or the traffic transmitted to it. Each mobile node is also able to transmit less traffic by reducing its ratio of transmission probability and receiving probability (b/c), without any central information.…”

Blind synchronization in asynchronous multiuser packet networks using KMA

“…The resulting data model then has the form The modulation of source 1 is assumed to be constant modulus, i.e. |s (1) k | = 1. The modulation of the other users is arbitrary.…”

“…Currently, if two packets are overlapping, both are lost and have to be retransmitted. Obviously, such a scheme will break down if the traffic load becomes too large, unless new approaches to medium access control are considered, e.g., [1].…”