Multi-packet Reception Capability Research Articles

Channel-Aware Random Access in the Presence of Channel Estimation Errors

In this work, we consider the random access of nodes adapting their transmission probability based on the local channel state information (CSI) in a decentralized manner, which is called CARA. The CSI is not directly available to each node but estimated with some errors in our scenario. Thus, the impact of imperfect CSI on the performance of CARA is our main concern. Specifically, an exact stability analysis is carried out when a pair of bursty sources are competing for a common receiver and, thereby, have interdependent services. The analysis also takes into account the compound effects of the multipacket reception (MPR) capability at the receiver. The contributions in this paper are twofold: first, we obtain the exact stability region of CARA in the presence of channel estimation errors; such an assessment is necessary as the errors in channel estimation are inevitable in the practical situation. Secondly, we compare the performance of CARA to that achieved by the class of stationary scheduling policies that make decisions in a centralized manner based on the CSI feedback. It is shown that the stability region of CARA is not necessarily a subset of that of centralized schedulers as the MPR capability improves.

Stability Analysis of Frame Slotted Aloha Protocol

Frame Slotted Aloha (FSA) protocol has been widely applied in Radio Frequency Identification (RFID) systems as the de facto standard in tag identification. However, very limited work has been done on the stability of FSA despite its fundamental importance both on the theoretical characterization of FSA performance and its effective operation in practical systems. In order to bridge this gap, we devote this paper to investigating the stability properties of $p$ -persistent FSA by focusing on two physical layer models of practical importance, the models with single packet reception and multipacket reception capabilities. Technically, we model the FSA system backlog as a Markov chain with its states being backlog size at the beginning of each frame. The objective is to analyze the ergodicity of the Markov chain and demonstrate its properties in different regions, particularly the instability region. By employing drift analysis, we obtain the closed-form conditions for the stability of FSA and show that the stability region is maximized when the frame length equals the number of packets to be sent in the single packet reception model and the upper bound of stability region is maximized when the ratio of the number of packets to be sent to frame length equals in an order of magnitude the maximum multipacket reception capacity in the multipacket reception model. Furthermore, to characterize system behavior in the instability region, we mathematically demonstrate the existence of transience of the backlog Markov chain. Finally, the analytical results are validated by the numerical experiments.

Design and performance analysis of a MAC protocol for wireless LANs supporting multipacket reception

Recent advances in physical layer technologies, allows simultaneous reception of multiple packets by a node. This promising technology is called Multi-Packet Reception (MPR). In this paper, we analyze a modified IEEE 802.11 DCF based medium access control (MAC) protocol for Wireless Local Area Network (WLAN) with nodes having MPR capability. Our protocol modifies the backoff mechanism of the IEEE 802.11 DCF so that the backoff process quickly adapts to the prevailing traffic conditions while leveraging MPR. A Markov chain model for the backoff process of the nodes with MPR capability has been derived. Further a Markov chain model to capture the state of the MPR channel has been derived. Solving the Markov chains for stationary probabilities, we derive the saturated throughput and energy efficiency of our protocol. Effect of the number of nodes, MPR capability, contention window size, and sensing errors on the saturation throughput has been investigated. Proposed analytical model has been validated through extensive simulations. Our investigation has the potential to aid in the development of next generation WLAN MAC protocol.

Flow Allocation for Maximum Throughput and Bounded Delay on Multiple Disjoint Paths for Random Access Wireless Multihop Networks

In this paper, we consider random access, wireless, multi-hop networks, with multi-packet reception capabilities, where multiple flows are forwarded to the gateways through node disjoint paths. We explore the issue of allocating flow on multiple paths, exhibiting both intra- and inter-path interference, in order to maximize average aggregate flow throughput (AAT) and also provide bounded packet delay. A distributed flow allocation scheme is proposed where allocation of flow on paths is formulated as an optimization problem. Through an illustrative topology it is shown that the corresponding problem is non-convex. Furthermore, a simple, but accurate model is employed for the average aggregate throughput achieved by all flows, that captures both intra- and inter-path interference through the SINR model. The proposed scheme is evaluated through Ns2 simulations of several random wireless scenarios. Simulation results reveal that, the model employed, accurately captures the AAT observed in the simulated scenarios, even when the assumption of saturated queues is removed. Simulation results also show that the proposed scheme achieves significantly higher AAT, for the vast majority of the wireless scenarios explored, than the following flow allocation schemes: one that assigns flows on paths on a round-robin fashion, one that optimally utilizes the best path only, and another one that assigns the maximum possible flow on each path. Finally, a variant of the proposed scheme is explored, where interference for each link is approximated by considering its dominant interfering nodes only.

Optimal ALOHA-Like Random Access With Heterogeneous QoS Guarantees for Multi-Packet Reception Aided Visible Light Communications

There is a paucity of random access protocols designed for alleviating collisions in visible light communication (VLC) systems, where carrier sensing is hard to achieve due to the directionality of light. To resolve the problem of collisions, we adopt the successive interference cancellation (SIC) algorithm to enable the coordinator to simultaneously communicate with multiple devices, which is referred to as the multi-packet reception (MPR) capability. However, the MPR capability could be fully utilized only when random access algorithms are properly designed. Considering the characteristics of the SIC aided random access VLC system, we propose a novel effective capacity (EC)-based ALOHA-like distributed random access algorithm for MPR-aided uplink VLC systems having heterogeneous quality-of-service (QoS) guarantees. First, we model the VLC network as a conflict graph and derive the EC for each device. Then, we formulate the VLC QoS-guaranteed random access problem as a saturation throughput maximization problem subject to multiple statistical QoS constraints. Finally, the resultant non-concave optimization problem is solved by a memetic search algorithm relying on invasive weed optimization and differential evolution. We demonstrate that our derived EC expression matches the Monte Carlo simulation results accurately, and the performance of our proposed algorithms is competitive.

Throughput of a cooperative energy harvesting secondary user in cognitive radio networks

AbstractThis paper investigates the maximum throughput of a rechargeable secondary user (SU) sharing the spectrum with a primary user (PU). The SU is assumed to be an energy harvesting node, which harvests energy packets from the environmental energy sources (e.g. solar, wind and acoustics) with a certain harvesting rate. The PU is equipped with a data buffer to store the randomly arrived data packets at its receiver. In addition to its own data buffer, the SU is equipped with another data buffer for storing the unsuccessfully decoded packets at the primary destination in a given time slot due to channel fading. Moreover, it has an energy buffer for storing the energy packets harvested from the environment. We propose a new cooperative cognitive relaying protocol that allows the SU to gain channel access when it relays a fraction of the undelivered primary packets. We consider an interference channel model [or a multipacket reception (MPR) channel model], where simultaneous transmissions can be decoded correctly at the corresponding destinations with certain decoding probabilities characterised by the complement of channel outages under interference. Our proposed protocol exploits the PU's data burstiness because of the random and sporadic packet arrival at its queue. Moreover, the proposed protocol takes advantage of the receivers' MPR capabilities. In addition, it efficiently expends the secondary energy packets under the objective of secondary throughput maximisation. Our numerical results show the benefits of cooperation, receivers' MPR capabilities and secondary energy queue arrival rate on the system's performance from a network layer standpoint. Copyright © 2016 John Wiley & Sons, Ltd.

A Handshake-Based Protocol Exploiting the Near-Far Effect in Underwater Acoustic Networks

We propose a scheme that opportunistically exploits received power diversity across different packets to both favor spatial reuse in underwater acoustic networks and limit the exposed terminal problem. Since the power attenuation in the underwater acoustic channel is large, such power differences are common. This situation, also referred to as the near-far effect and often considered a problem, is converted into a resource by means of multipacket reception (MPR). Yet, even without MPR capability our scheme offers performance benefits. Our scheme is simple, lightweight and distributed, and can be easily implemented over any protocol based on carrier-sense multiple access with collision avoidance. Our results show that higher throughput and lower transmission delay are achieved compared to a benchmark channel access protocol. Our results are validated and demonstrated in a lake experiment. To allow reproducibility, the implementation of our scheme is publicly available.

A MPR optimization algorithm for FSO communication system with star topology

In this paper, we introduce the multi-packet reception (MPR) technology to the outdoor free space optical (FSO) communication system to provide excellent throughput gain. Hence, we address two challenges: how to realize the MPR technology in the varying atmospheric turbulence channel and how to adjust the MPR capability to support as many devices transmitting simultaneously as possible in the system with bit error rate (BER) constraints. Firstly, we explore the reliability ordering with minimum mean square error successive interference cancellation (RO-MMSE-SIC) algorithm to realize the MPR technology in the FSO communication system and derive the closed-form BER expression of the RO-MMSE-SIC algorithm. Then, based on the derived BER expression, we propose the adaptive MPR capability optimization algorithm so that the MPR capability is adapted to different turbulence channel states. Consequently, the excellent throughput gain is obtained in the varying atmospheric channel. The simulation results show that our RO-MMSE-SIC algorithm outperforms the conventional MMSE-SIC algorithm. And the derived exact BER expression is verified by Monte Carlo simulations. The validity and the indispensability of the proposed adaptive MPR capability optimization algorithm are verified as well.

Relay-Assisted Multiple Access With Full-Duplex Multi-Packet Reception

The effect of full-duplex cooperative relaying in a random access multiuser network is investigated here. First, we model the self-interference incurred due to full-duplex operation, assuming multi-packet reception capabilities for both the relay and the destination node. Traffic at the source nodes is considered saturated and the cooperative relay, which does not have packets of its own, stores a source packet that it receives successfully in its queue when the transmission to the destination has failed. We obtain analytical expressions for key performance metrics at the relay, such as arrival and service rates, stability conditions, and average queue length, as functions of the transmission probabilities, the self interference coefficient, and the links' outage probabilities. Furthermore, we study the impact of the relay node and the self-interference coefficient on the per-user and aggregate throughput, and the average delay per packet. We show that perfect self-interference cancelation plays a crucial role when the SINR threshold is small, since it may result to worse performance in throughput and delay comparing with the half-duplex case. This is because perfect self-interference cancelation can cause an unstable queue at the relay under some conditions.

An integrated PHY-MAC analytical model for IEEE 802.15.7 VLC network with MPR capability

Considering that the collision caused by hidden terminal is particularly serious due to the narrow beams of optical devices, the multi-packet reception (MPR) is introduced to mitigate the collisions for IEEE 802.15.7 visible light communication (VLC) system. To explore the impact of MPR on system performance and investigate the interaction between physical (PHY) layer and media access control (MAC) layer, a three dimensional (3D) integrated PHY-MAC analytical model of carrier sense multiple access/collision avoidance (CSMA/CA) is established based on Markov chain theory for VLC system, in which MPR is implemented through the use of orthogonal code sequence. Throughput is derived to evaluate the performance of VLC system with MPR capability under imperfect optical channel. The results can be used for the performance optimization of a VLC system with MPR capability.

Cognitive Cooperative Random Access for Multicast: Stability and Throughput Analysis

In this paper, we investigate the queue stability and throughput of a two-user cognitive radio system with multicast traffic. We study the impact of network-level cooperation, in which one of the nodes can relay the packets of the other user that are not received at the destinations. Under this approach, if a packet transmitted by the primary user is not successfully received by the destination set but is captured by the secondary source, then the secondary user assumes responsibility for completing the transmission of the packet; therefore, the primary releases it from its queue, enabling it to process the next packet. We demonstrate that the stability and throughput regions of this cooperative approach is larger than that of the noncooperative approach, which translates into a benefit for both users of this multicast system. Our system model allows for the possibility of multipacket reception (MPR), and the optimal transmission strategies for different levels of MPR capability are observed in our numerical results. In addition to achieving a larger stability region, our results show that cooperation can result in reduced average delay for both primary and secondary users.

Stability and performance issues of a relay assisted multiple access scheme with MPR capabilities

In this work, we study the impact of a relay node to a network with a finite number of users-sources and a destination node. We assume that the users have saturated queues and the relay node does not have packets of its own; we have random access of the medium and the time is slotted. The relay node stores a source packet that it receives successfully in its queue when the transmission to the destination node has failed. The relay and the destination nodes have multi-packet reception capabilities. We obtain analytical equations for the characteristics of the relay’s queue such as average queue length, stability conditions etc. We also study the throughput per user and the aggregate throughput for the network.

Admission control for wireless LANs with multipacket reception capability

AbstractIn a multipacket reception (MPR) system, a wireless node can successfully receive multiple packets from simultaneous transmitters. The increase in the number of simultaneous transmissions leads to higher throughput as long as the transmissions can be successfully decoded by the receiver. The maximum number of simultaneous transmissions that the receiver can successfully decode should be determined and used as the criterion of admission control in order to maximise the multipacket reception system performance. In this paper, we propose an admission control scheme that derives the maximum number of simultaneous transmissions and regulates the number of simultaneous transmissions based on the derived number. To evaluate the performance of our proposed scheme, we carry out extensive simulations and show that our proposed scheme significantly improves the network throughput. Copyright © 2013 John Wiley & Sons, Ltd.

Optimal Random Access for a Cognitive Radio Terminal with Energy Harvesting Capability

We consider a cognitive radio scenario with an energy harvesting secondary user (SU) attempting to access a primary channel randomly. We assume multipacket reception (MPR) capability and investigate a system in which the SU may or may not exploit the primary feedback messages. The access probabilities are obtained to maximize the secondary throughput under the constraints of primary queue stability and such that the primary queueing delay is kept below a specified value in order to guarantee a certain quality of service (QoS) for the primary user (PU). We investigate the impact of the energy queue arrivals, MPR capability, and the primary queueing delay constraint on the maximum secondary throughput.

Coordinating transmit power and carrier phase for wireless networks with multi-packet reception capability

Abstract Driven by advances in signal processing and multiuser detection (MUD) technologies, it has become possible for a wireless node to simultaneously receive multiple signals from other transmitters. In order to take full advantage of MUD in multi-packet reception (MPR) capable wireless networks, it is highly desirable to make the compound signals from multiple transmitters more separable on its constellation at the receiver by coordinating both the transmit power level and carrier phase offsets of the transmitters. In this article, we propose a feedback-based transmit power and carrier phase adjustment scheme that estimates the symbol energy and the carrier phase offset for each transmitter’s received signal, computes the optimal received power level and carrier phase shift to maximize the minimum Euclidean distance between the constellation points, and finally feeds the optimal transmit power level and phase shift information back to the transmitters. We then evaluate the performance of the proposed transmit power and carrier phase adjustment scheme and subsequently show that the proposed scheme significantly reduces the error probability in a multiuser communication system having MPR capability.

Asynchronous Medium Access Protocol for Multi-User MIMO Based Uplink WLANs

Multi-user multiple-input multiple-output (MIMO) technology makes it possible for wireless nodes to successfully receive multiple packets from simultaneous transmitters in wireless networks. As it can provide more transmission opportunities without causing collisions, the network throughput performance can be dramatically improved. In this paper, we propose an asynchronous medium access control (MAC) protocol, which enables senders to independently start their transmissions if the access point (AP) can receive more simultaneous packets up to its multi-packet reception capability. This asynchronous protocol makes the multi-user MIMO channel more efficiently used, especially in wireless networks where transmission durations are dynamically varying due to different packet sizes and transmission rates. Through our performance analysis and extensive simulations, we show that the proposed asynchronous MAC protocol achieves significantly higher uplink throughput performance in multi-user MIMO wireless networks.

On the Stability of Random Multiple Access With Stochastic Energy Harvesting

In this paper, we consider random access by nodes that have energy harvesting capability. Each node is equipped with both a queue for storing the arriving packets and a battery for storing the harvested energy chunks, where the packet arrival and the energy harvesting events are all modeled as discrete-time stochastic processes. In each time slot, each node attempts to transmit the head-of-the-line packet in the queue with some probability if its battery is non-empty, and each transmission consumes one chunk of energy. Therefore, the transmission by one node is not just limited by the availability of packets in the queue but also by the availability of energy chunks in the battery. In most of related previous work, it was implicitly assumed that there exists unlimited energy for transmission, which is impractical in many distributed systems. In this work, we characterize the exact stability region when a pair of bursty nodes, which are harvesting energy from the environment, are randomly accessing a common receiver. The analysis takes into account the compound effects of multi-packet reception capability at the receiver. The contributions in the paper are twofold. First, we accurately assess the effect of limited, but renewable, energy availability due to harvesting on the stability region by comparing against the case of having unlimited energy. Second, the impact of the finite capacity batteries on the achieved stability region is also quantified.

Neighbor discovery in a wireless sensor network: Multipacket reception capability and physical-layer signal processing

In randomly deployed networks, such as sensor networks, an important problem for each node is to discover its \textit{neighbor} nodes so that the connectivity amongst nodes can be established. In this paper, we consider this problem by incorporating the physical layer parameters in contrast to the most of the previous work which assumed a collision channel. Specifically, the pilot signals that nodes transmit are successfully decoded if the strength of the received signal relative to the interference is sufficiently high. Thus, each node must extract signal parameter information from the superposition of an unknown number of received signals. This problem falls naturally in the purview of random set theory (RST) which generalizes standard probability theory by assigning \textit{sets}, rather than values, to random outcomes. The contributions in the paper are twofold: first, we introduce the realistic effect of physical layer considerations in the evaluation of the performance of \textit{logical} discovery algorithms; such an introduction is necessary for the accurate assessment of how an algorithm performs. Secondly, given the \textit{double} uncertainty of the environment (that is, the lack of knowledge of the number of neighbors along with the lack of knowledge of the individual signal parameters), we adopt the viewpoint of RST and demonstrate its advantage relative to classical matched filter detection method.

MMM: multi-channel TDMA with MPR capabilities for MANETs

Many Ad-hoc networks for military and public safety environments are characterized by: large number of nodes in the same area (that means that frequency spatial reuse is less applicable), crucial situation awareness (which implies periodically frequent location updates, mission status, etc.), or high propagation delay (for example, acoustic or airborne networks). In order to support such networks, an efficient medium access control broadcast protocol is essential. Obviously, using one shared channel with only one packet reception at a time is not scalable and therefore multi-packet reception techniques are more suitable. Recent technological developments (patent pending) enable nodes to receive messages simultaneously in many, even hundreds of channels. In this paper we study the impact of the new multi packet reception capabilities. In order to compute close upper and lower bounds on the maximum delay, we consider the best scenario that is, the simple case of full mesh. We then propose algorithms that achieve a close to the best possible maximum delay between updates over all pairs of nodes. This is done by providing close upper and lower bounds on the maximum delay and giving simple algorithms that meet the upper bound. For theoretical completeness we study bounds for all possible relations between the number of nodes and the number of channels.

Theoretical Analysis of the Capture Probability in Wireless Systems with Multiple Packet Reception Capabilities

In this paper, we address the problem of computing the probability that r out of n interfering wireless signals are "captured," i.e., received with sufficiently large Signal to Interference plus Noise Ratio (SINR) to correctly decode the signals by a receiver with multi-packet reception (MPR) and Successive Interference Cancellation (SIC) capabilities. We start by considering the simpler case of a pure MPR system without SIC, for which we provide an expression for the distribution of the number of captured packets, whose computational complexity scales with n and r. This analysis makes it possible to investigate the system throughput as a function of the MPR capabilities of the receiver. We then generalize the analysis to SIC systems. In addition to the exact expressions for the capture probability and the normalized system throughput, we also derive approximate expressions that are much easier to compute and provide accurate results in some practical scenarios. Finally, we present selected results for some case studies with the purpose of illustrating the potential of the proposed mathematical framework and validating the approximate methods.