Abstract
In mobile ad hoc radio networks, mechanisms on how to access the radio channel are extremely important in order to improve network efficiency. In this paper, the load adaptable medium access control for ad hoc networks (LAMAN) protocol is described. LAMAN is a novel decentralized multipacket MAC protocol designed following a cross-layer approach. Basically, this protocol is a hybrid CDMA-TDMA-based protocol that aims at throughput maximization in multipacket communication environments by efficiently combining contention and conflict-free protocol components. Such a combination of components is used to adapt the nodes' access priority to changes on the traffic load while, at the same time, accounting for the multipacket reception (MPR) capability of the receivers. A theoretical analysis of the system is developed presenting closed expressions of network throughput and packet delay. By simulations, the validity of our analysis is shown and the performances of a LAMAN-based system and an Aloha-CDMA-based one are compared.
Highlights
Medium access control (MAC) mechanisms are used to face off the classical collision resolution problem in multiple-access channels with single-packet communications
We note that cross-layer interaction is used in order to improve and reach an optimal system performance and that the fact that codes are allocated in a decentralized fashion is, to the best of our knowledge, a totally new approach in ad hoc networks
For an M-node network, the Markov chain is extended to a two-dimensional (Nc + 1) × M state chain which models both the number of backlogged packets in the multiple-node buffer which is in the range of [0, Nc] and the number of simple nodes in the backlogged state which is in the range of [0, M − 1]
Summary
Medium access control (MAC) mechanisms are used to face off the classical collision resolution problem in multiple-access channels with single-packet communications. Some papers in the literature refer to the PHY layer MPR capability by using the so-called MPR matrix C, and use this MPR matrix in the development of centralized MAC procedures [11, 12, 13] Each element of this matrix, cm,k, is the probability of successfully received k packets when m packets have been sent. Assuming that each node has a packet with probability qi and considering the MPR receiver matrix, an optimal node access set is obtained in order to schedule node’s access to the channel aiming at packet delay minimization and network throughput maximization. We note that cross-layer interaction (see Figure 1) is used in order to improve and reach an optimal system performance and that the fact that codes are allocated in a decentralized fashion is, to the best of our knowledge, a totally new approach in ad hoc networks.
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