From practical and theoretical viewpoints, performance analysis of communication systems by using information-theoretic results is important. In this paper, based on our previous work on Multiple Access Channel (MAC) and Multiple Access Relay Channel (MARC), we analyze the impact of a relay on the fundamental wireless communications concept, i.e., coverage region of MARC, as a basic model for u...

in recent years, many researchers have been done in the area of wireless sensornetworks that has led to the variety of algorithms and methods for the collection andtransmission of environment information; but still many challenges faced bywireless sensor networks using methodologies are applied in various fields. such asmedia access control that due to the media being shared on these networks, ...

Ultra-WideBand (UWB) has been recently presented as a promising radio technology due to the large bandwidth available. This feature enables point to point high data rates at short range as well as high temporal resolution with long channel impulse reponses (CIR). In this paper, we present an original multiple access scheme called Channel Division Multiple Access (ChDMA), where we use the CIR as...

Traditionally, random access protocols have been designed and studied by assuming simple models for the physical layer. We introduce a reception model that incorporates the channel states of the transmitting users and allows for multiple simultaneous successes. We assume that each user has access to his channel state and propose a variant of the Slotted ALOHA protocol for medium access where th...

The medium-access control (MAC) protocols for wireless networks proposed or implemented to date based on collision-avoidance handshakes between sender and receiver either require carrier sensing or the assignment of unique codes to nodes to ensure that intended receivers hear data packets without interference from hidden sources. We present and analyze a protocol that we call channel-hopping mu...