Multiple access channel with feedback is an extension of classical MAC, by providing senders with ability to observe the channel output. The capacity region in the general case is not known. This report presents the main results of [1] by Cover and Leung, which is a region of achievable rates exceeding the capacity region of classical MAC (section 3). Since the coding technique used in [1] reli...

this study seeks to examine how a company can select the best intermediary for its marketing channels with minimum of criteria and time. a theoretical framework is proposed based on the most important tasks of intermediary and the criteria to measure them. there are four basic tasks and thirty criteria in three independent levels. subsequently, an exploratory case study in iranian food industry...

Extensive researches on Wireless Sensor Networks (WSNs) have been performed and many techniques have been developed for the data link (MAC) layer. Most of them assume single-channel MAC protocols. In the usual dense deployment of the sensor networks, single-channel MAC protocols may be deficient because of radio collisions and limited bandwidth. Hence, using multiple channels can significantly ...

Extensive researches on Wireless Sensor Networks (WSNs) have been performed and many techniques have been developed for the data link (MAC) layer. Most of them assume single-channel MAC protocols. In the usual dense deployment of the sensor networks, single-channel MAC protocols may be deficient because of radio collisions and limited bandwidth. Hence, using multiple channels can significantly ...

In CDMA (Code - Division Multiple - Access) systems multi - user accessing of a channel is possible. Under the assumptions of Optimum multi - user and decorrelating detector in CDMA systems. By using signals with zero and / or identical cross correlations, a simple and expandable decorrelating detector with optimum efficiency which can be easily implemented are proposed. Constructing these sign...

We consider a time slotted cognitive radio network under Rayleigh fading where multiple secondary users (SUs) contend for spectrum usage over available primary users’ channels. We analyze the performance of a channel access policy where each SU stochastically determines whether to access a wireless channel or not based on a given access probability. In the analysis, we focus on the queueing per...

In this paper, we propose an opportunistic channel access scheme based on weighted residual entropy function in cognitive radio networks. This central decision scheme significantly improves spectrum utilization compared with random and first opportunistic spectrum access schemes. Particularly, in this mechanism, appropriate spectrum opportunity will be selected based on the usefulness of idle c...