We propose and analyse three different power selection schemes for slotted ALOHA random access protocol operating under multiple power levels. Through analysis and numerical examples we demonstrate that these schemes can significantly improve the performance of slotted ALOHA, in terms of throughput and stability, under heavy load. The proposed schemes are truly distributive in nature and can be...

The random access protocols with multi packet reception (MPR), which include both slotted-Aloha and slotted τ-persistent CSMA protocols. For both protocols, each node makes a transmission attempt in a slot with a given probability. The transmission channel is divided into equal slot using slottedAloha, then CSMA is used to check whether the channel is idle or not. CSMA is used to avoid collisio...

In this paper, we assess the performance of the slotted ALOHA protocol with capture in a mobile communications environment with Rayleigh and Log-normal fading when used with switched-beam smart antennas. We consider the configuration where one receiver is present at each base station and calculate the capture probability, its asymptotic value as the number of colliding packets tends to infinity...

In this paper, we present a new MAC (Medium Access Control) protocol, called Hybrid ALOHA (H-ALOHA), which is combination of two existing protocols: Pure (P-ALOHA) protocol and Slotted (S-ALOHA) protocol. The idea behind it to design that could meet some specific requirements in wireless networks, such as reducing energy consumption, delay minimization, increasing the throughput. To best our kn...

We consider the problem of stability of slotted ALOHA for a system consisting of N users communicating with a common receiver, which employs spatial diversity to receive multiple transmissions simultaneously. We introduce a general packet reception model to incorporate multiple packet receptions since the collision channel model is no longer valid in such a scenario. We characterize the stabili...

We introduce minislotted threshold ALOHA (MiSTA), a slotted modification designed to minimize the network-wide time average Age of Information (AoI). In MiSTA, sources whose ages are below certain stay silent. A node with age above becomes active in next frame probability. The first transmits short control sequence minislot ahead actual data transmission, and if collision is sensed, it backs of...

We present time-parallel algorithms for parallel simulation of multiple access protocols for medium access – in particular, slotted Aloha and slotted -persistent CSMA. Two mechanisms are presented — regeneration point-based and fix up-based. Aloha is simulated using both mechanisms and CSMA is simulated using only the first mechanism. An analytical technique is developed to predict speedup for ...

The problems of identifying a set of tagged objects simultaneously in an RFID network have hampered the adoption of RFID universally. When multiple tags transmit their IDs in a single period of time to a single reader over a shared wireless channel, the tag signals may collide. This collision will disturb the reader’s identification process. Hence, we proposed a modified version of Accelerated ...

Slotted Aloha is an effective random access protocol and can also be an important element of more advanced media access protocols. This paper investigates slotted Aloha in a radio environment with multiple access points. Specifically, we examine the impact of multi-access-point (multi-AP) diversity on the performance of slotted Aloha. The paper considers both omni-directional (OM) and beamformi...