Multi-packet Reception Capability Research Articles

Distributed splitting-tree-based medium access control protocol for multiaccess wireless networks with multipacket reception

The conventional medium access control (MAC) protocols assume that only one packet can be received at a given time. However, with the advent of spread spectrum, antenna arrays or sophisticated signal processing techniques, it is possible to achieve multipacket reception (MPR) in wireless communication networks. A distributed splitting-tree-based MAC protocol that can exploit the MPR capability in the networks is proposed. For the MPR MAC protocol, a closed-form expression of the system throughput is derived based on a Markov chain model. The experimental results show that the MPR protocol can considerably increase the spectrum efficiency compared with the splitting-tree algorithm with its conventional collision resolution method.

Game Theoretic Cross-Layer Transmission Policies in Multipacket Reception Wireless Networks

We study the structure of the optimal transmission policies for noncooperating nodes in a finite-size random access wireless network, where the medium access control (MAC) protocol is a variant of the time-slotted ALOHA protocol. It is assumed that the network has the multipacket reception capability and every node knows its channel state information (CSI), which is continuously distributed, perfectly at the beginning of each transmission time slot. The objective of each node in the network is to find a transmission policy mapping CSI to transmission probabilities to maximize its individual utility. The problem is formulated as a noncooperative game of a finite number of rational players and actions with a continuous channel state space. We prove that if the probability of success of a node is a nondecreasing function of its CSI, there exists a threshold transmission policy that maximizes its utility. It is then shown that there exists a Nash equilibrium at which every node adopts a threshold policy. The optimality of threshold policies strongly simplifies the problem of optimizing the transmission policy for a node. We propose a stochastic-gradient-based algorithm that exhibits the best response dynamic adjustment process for the transmission game. The theoretical results of the paper as well as the performance of the proposed algorithm are illustrated via numerical examples

A novel multiple access scheme over multi-packet reception channels for wireless multimedia networks

Recent advances in signal processing techniques have enabled wireless networks to have multi-packet reception (MPR) capability at the physical layer, where it is possible to receive more than one packets when concurrent transmissions occur. In this paper, we propose a novel multi-reservation multiple access (MRMA) scheme for future wireless multimedia networks based on such an MPR channel model. MRMA can fully exploit the channel's MPR capacity while fulfilling the quality of service requirements of different multimedia traffic. Similar to many existing reservation protocols, MRMA guarantees (i) bounded access delay for real-time traffic by dropping packets not transmitted within the required delay bound, and (ii) satisfaction of the required packet loss ratio when applied in conjunction with a connection admission control method to limit the number of admitted traffic streams. MRMA further incorporates a priority control mechanism to differentiate guaranteed and best-effort services for real-time voice/video and connectionless data, respectively. Analytical and simulation results are presented to illustrate the effectiveness of MRMA in service differentiation and increasing the number of admitted traffic streams

Predictive multicast polling for wireless networks with multipacket reception and queuing

In this paper, we propose the predictive multicast polling scheme for medium access control in wireless networks with multipacket reception capability. We concentrate on the case in which the packet arrival process is general and the maximum queue size is finite but larger than one. We derive both analytical results and simulation results. We use the theory of discrete-time Markov chain to analyze the evolution of the system state. In addition, we propose to use Markov reward processes to calculate the exact value of the network throughput. Furthermore, we obtain the average system size, the packet blocking probability, and the average packet delay. We show that our numerical results are consistent with simulation results. We also use simulation results to justify the usage of the proposed approach. Our study shows that the system performance can be significantly improved with a few additional buffers in the queues.

Stability and Delay of Finite-User Slotted ALOHA With Multipacket Reception

The effect of multipacket reception (MPR) on stability and delay of slotted ALOHA based random-access systems is considered. A general asymmetric MPR model is introduced and the medium-access control (MAC) capacity region is specified. An explicit characterization of the ALOHA stability region for the two-user system is given. It is shown that the stability region undergoes a phase transition from a concave region to a convex polyhedral region as the MPR capability improves. It is also shown that after this phase transition, slotted ALOHA is optimal i.e., the ALOHA stability region coincides with the MAC capacity region. Further, it is observed that there is no need for transmission control when ALOHA is optimal i.e., ALOHA with transmission probability one is optimal. Next, these results are extended to a symmetric N>2 user ALOHA system. Finally, a complete characterization of average delay in capture channels for the two-user system is given. It is shown that in certain capture scenarios, ALOHA with transmission probability one is delay optimal for all stable arrival rates. Further, it is also shown that ALOHA with transmission probability one is optimal for stability and delay simultaneously in the two-user capture channel.

LAMAN: Load Adaptable MAC for Ad Hoc Networks

In mobile ad hoc radio networks, mechanisms on how to access the radio channel are extremely important in order to improve network efficiency. In this paper, the load adaptable medium access control for ad hoc networks (LAMAN) protocol is described. LAMAN is a novel decentralized multipacket MAC protocol designed following a cross-layer approach. Basically, this protocol is a hybrid CDMA-TDMA-based protocol that aims at throughput maximization in multipacket communication environments by efficiently combining contention and conflict-free protocol components. Such a combination of components is used to adapt the nodes' access priority to changes on the traffic load while, at the same time, accounting for the multipacket reception (MPR) capability of the receivers. A theoretical analysis of the system is developed presenting closed expressions of network throughput and packet delay. By simulations, the validity of our analysis is shown and the performances of a LAMAN-based system and an Aloha-CDMA-based one are compared.

A Dynamic Queue Protocol for Multiaccess Wireless Networks With Multipacket Reception

A dynamic medium access control (MAC) protocol is proposed for a finite-user slotted channel with multipacket reception (MPR). This protocol divides the time axis into transmission periods (TPs) where the ith TP is dedicated to the transmission of the packets generated in the (i-1)th TP. At the beginning of each TP, the state (active or idle) of each user is estimated based on the length of the previous TP and the incoming traffic load. By exploiting the information on the state of users and the channel MPR capability, the number of users who can simultaneously access the channel in the current TP is chosen so that the expected length of this TP is minimized. As a result, the MPR capability is more efficiently utilized by the proposed protocol as compared to, for example, the slotted ALOHA with optimal retransmission probability. Furthermore, the proposed protocol requires little online computation. Its simplicity is comparable to that of slotted ALOHA. It can be applied to random access networks with spread spectrum and/or antenna array.

A multiqueue service room MAC protocol for wireless networks with multipacket reception

An adaptive medium-access control (MAC) protocol for heterogeneous networks with finite population is proposed. Referred to as the multiqueue service room (MQSR) protocol, this scheme is capable of handling users with different quality-of-service (QoS) constraints. By exploiting the multipacket reception (MPR) capability, the MQSR protocol adaptively grants access to the MPR channel to a number of users such that the expected number of successfully received packets is maximized in each slot. The optimal access protocol avoids unnecessary empty slots for light traffic and excessive collisions for heavy traffic. It has superior throughput and delay performance as compared to, for example, the slotted ALOHA with the optimal retransmission probability. This protocol can be applied to random-access networks with multimedia traffic.

Optimal decentralized control in the random access multipacket channel

A decentralized control algorithm is sought that maximizes the stability region of the infinite-user slotted multipacket channel and is easily implementable. To this end, the perfect state information case in which the stations can use the instantaneous value of the backlog to compute the retransmission probability is studied first. The vest throughput possible for a decentralized control protocol is obtained, as well as an algorithm that achieves it. These results are then applied to derive a control scheme when the backlog is unknown, which is the case of practical relevance. This scheme, based on a binary feedback, is shown to be optimal, given some restrictions on the channel multipacket reception capability.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Stability properties of slotted Aloha with multipacket reception capability

The stability of the Aloha random-access algorithm in an infinite-user slotted channel with multipacket-reception capability is considered. This channel is a generalization of the usual collision channel, in that it allows the correct reception of one or more packets involved in a collision. The number of successfully received packets in each slot is modeled as a random variable which depends exclusively on the number of simultaneously attempted transmissions. This general model includes as special cases channels with capture, noise, and code-division multiplexing. It is shown by drift analysis that the channel backlog Markov chain is ergodic if the packet-arrival rate is less than the expected number of packets successfully received in a collision of n as n goes to infinity. The properties of the backlog in the nonergodicity region are examined. >