Performance analysis of a fully-connected, full-duplex CDMA ALOHA network with channel sensing and collision detection

In cases where machines having bursty data are equally likely to transmit to one another, code-division multiple-access (CDMA) ALOHA which allows for an individual "virtual channel" for each receiving station may be a better multiple-access protocol than simple ALOHA. With the use of "receiver-based code" multiple-access protocol, it is also possible for a station to listen to the channel of the intended receiver before transmission, and also abort transmission when it detects others transmitting on the same channel. This paper describes a model for a fully-connected, full duplex, and slotted CDMA ALOHA network where channel sensing and collision detection are used. The model is analyzed using a discrete time Markov chain and some numerical results are presented. For a system with a large number of users, where Markov analysis is impractical, equilibrium point analysis is used to predict the stability of the system, and estimate the throughput as well as the delay performance of the system when it is stable. Finally, a comparison is made with a simple channel sense multiple-access with collision detection (CSMA-CD) network, showing that a substantial improvement in the performance is achieved by the proposed network.published_or_final_versio

Performance of multichannel CSMA networks

International Conference on Information, Communications and Signal Processing, Singapore, 9-12 September 1997Channel sense multiple access with collision detection (CSMA/CD) is a very simple and efficient way of allowing many stations to transmit messages to a central server down a shared channel. In wireless networks, however, collision detection is difficult to implement, and in such cases CSMA alone may have to be used. In this paper, it is shown that a multichannel CSMA network can be almost as efficient in utilizing the bandwidth available to the network as an equivalent single-channel CSMA/CD network. Furthermore, multichannel CSMA networks provide better throughput and delay performance than equivalent single channel CSMA systems, even when the message generation probability and the number of stations in the network are varied.published_or_final_versio

Performance analysis of a CDMA ALOHA network with channel sensing

It has been shown in [1] that the throughput-delay performance of a CDMA ALOHA network, where each station is assigned a spreading code so that each effectively has its own `virtual channel', and where channel sensing and collision detection are also used, is much better than that of a simple CSMA-CD network. Such a system, however, is difficult to implement. A simpler system that may provide good performance and that is easy to implement is a CDMA ALOHA network with just channel sensing. The channel sensing can be provided by a simple correlator and threshold device. In this paper, the performance of such a network is investigated, and some comparisons are made with those of the simple CSMA-CD network and the CDMA ALOHA network with both channel sensing and collision detection. It is shown that when the CDMA-CS network is stable, its performance is not much worse than that of a CDMA-CS/CD network, and much better than that of a simple single channel CSMA-CD system.published_or_final_versio