ALOHA systems are some of the most attractive options for wireless applications which include packet transmission. However, despite their exibility and simplicity, they present a very low channel throughput. The objective of this paper is to analyze the performance of Slotted ALOHA based vertical layered space-time, known as V-BLAST, systems over wireless links. The multiple transmit antennas i...

Radio frequency identification (RFID) is used to identify, track, and manage tagged animate or inanimate objects automatically using wireless communication technology. A serious concern faced by RFID technology is the collisions that occur among tag responses when queried by a reader that limits system performance significantly. Collisions bring extra delay, a waste of bandwidth, and extra ener...

We present the results of computer simulation of a new medium access control (MAC) protocol for a photonic ring network based on a combination of wavelengthand time-division multiple access (WDMA/ TDMA). The simulations show that the proposed protocol offers maximum throughput in excess of 90% of total network capacity, although for delay-sensitive traffic it is necessary to limit the offered t...

This paper explores an efficient Medium Access Control protocol for carrying data traffic via satellite. The Combined Free/Demand Assignment Multiple Access (CFDAMA) protocol combines free assignment of data slots with demand assignment, providing a minimum delay of one round trip time at low loads and the statistical multiplexing gains of demand assignment at high loads. The delay/utilisation ...

In this paper we propose two analytically tractable stochastic-geometric models of interference in adhoc networks using pure (non-slotted) Aloha as the medium access. In contrast the slotted model, the interference in pure Aloha may vary during the transmission of a tagged packet. We develop closed form expressions for the Laplace transform of the empirical average of the interference experienc...

An exciting application of Multi-hop Packet Radio Networks (MPRNet) is to provide communication services in environments without suitable infrastructure. One key design issue in MPRNet is the formulation of Medium Access Control (MAC) protocols. In this paper, the performance of two MAC protocols, Slotted ALOHA (S-ALOHA) and Spatial TDMA (S-TDMA), are investigated. In many MPRNet, the traffic l...

In this paper, the Slotted ALOHA protocol in a mobile radio environment, in the presence of Ricean fading, twofold antenna diversity and multiple reception capability, is considered. The capture probabilities and the average throughput are computed, and the issue of stability is addressed. It is shown that diversity can improve the system performance, although only to a certain extent. Some ext...

Recently, contention resolution diversity slotted ALOHA (CRDSA) has been introduced as a simple but effective improvement to slotted ALOHA. It relies on MAC burst repetitions and on interference cancellation to increase the normalized throughput of a classic slotted ALOHA access scheme. CRDSA allows achieving a larger throughput than slotted ALOHA, at the price of an increased average transmitt...

A framework for reducing the average reading time of passive RFID tags in dense environments is introduced. The proposed framework termed Accelerated Frame Slotted ALOHA (AFSA) can be used in conjunction with almost all RFID tag reading protocols that are based on frame slotted ALOHA. It is shown that AFSA reduces the tag reading time by avoiding the wastage in bit times due to collisions and i...

A multichannel random access protocol called FMCSA for multislot short messages is proposed in this paper to be used in access networks with large propagation delay. This protocol combines random access with the use of packet level forward error correction coding for new messages and scheduled retransmissions for partially received messages. Analytical and simulation results show that FMCSA can...