Single Packet Reception Research Articles

Deterministic Collision-Resilient Channel Rendezvous: Theory and Algorithm

We formulate and investigate the problem of distributed channel rendezvous in collision-prone wireless networks. Existing researches on this topic are mainly devoted to designing channel hopping sequences, each pair of which can overlap on a common channel within bounded delay. However, this overlap-based canonical rendezvous design does not take into account channel collision, which may render existing rendezvous algorithms fail to achieve bounded delay in collision-prone environment. Motivated by this observation, we formulate and investigate the collision-aware channel rendezvous problem in a generic scenario, where a collision occurs if more than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$C$ </tex-math></inline-formula> packets overlap in time on a same channel. Our generic formulation allows to model both the baseline single packet reception model with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$C=1$ </tex-math></inline-formula> and the more sophisticated multiple packet reception model with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$C &gt; 1$ </tex-math></inline-formula> . We further abstract the collision-aware rendezvous problem as the problem of constructing a robust rendezvous system. We establish the theoretical limit of the problem, guided by which we design a collision-resilient distributed rendezvous algorithm with truly bounded rendezvous delay. We then demonstrate the performance of our rendezvous algorithm both analytically and numerically.

Efficient Indoor Localization via Switched-Beam Antennas

Location-based services have become extremely popular. As a result, indoor localization has received a lot of attention from both industry and academia. Despite the plethora of existing approaches, no method can achieve high accuracy without major, expensive changes to existing systems. For example, to achieve good accuracy, fingerprinting methods require many APs within range of a client, time-of-arrival methods require tight synchronization, client hardware changes and line-of-sight, and direction-of-arrival methods require expensive antenna front ends and line-of-sight. In this paper, we take advantage of inexpensive, off-the-shelf switched-beam antennas (SBAs) to increase the diversity of measurements used for fingerprint-based localization. We show using experiments that a single AP equipped with $n$ n SBAs may infer equally rich localization information as $n$ n APs equipped with $n$ n omnidirectional antennas each, as long as the SBAs are properly configured. We then establish via extensive experiments that a single packet reception from a commodity client at a single AP equipped with a handful of SBAs (e.g., eight SBAs costing a couple of dollars more than omni antennas) achieves localization accuracy in the order of half a meter with or without line-of-sight, in any indoor environment, with zero airtime overhead and zero client support.

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.

Completely Irrepressible Sequences for Multiple-Packet Reception

In this paper, we study completely irrepressible (CI) sequences. For a slot-asynchronous communication system supporting $K$ users with such sequences, a key feature is that each user is guaranteed to be able to send out at least one contention-free packet in one common sequence period. This is a desirable property since it provides a bounded delay guarantee for medium access control (MAC) layer contention, in contrast to random access schemes. Generalizing previous studies on CI sequences, we investigate systems endowed with multiple-packet reception (MPR) capability $\gamma$ , $\mbox{2} \leq \gamma . That is, a packet transmission is successful if and only if the total number of transmissions in the channel at any point in time during its transmission is less than or equal to $\gamma$ . We investigate the minimum period $L$ of CI sequences for MPR as $L$ is a fundamental factor that affects the worst-case delay. The main result is that $L$ is asymptotically upper bounded by $\mbox{2}K^2/(\gamma-\mbox{2})$ when $\gamma \geq \mbox{3}$ . For $\gamma = \mbox{2}$ , the corresponding bound is $\mbox{2}K^2$ . In contrast, the bound for the single-packet reception system $(\gamma=\mbox{1})$ is $\mbox{4}K^2$ . Simulation results verify our analysis and present comparative studies between CI sequences and random access in an application of group-based detection in a wireless sensor network.

Neighbor Discovery in Wireless Networks with Multipacket Reception

Neighbor discovery is one of the first steps in configuring and managing a wireless network. Most existing studies on neighbor discovery assume a single-packet reception model where only a single packet can be received successfully at a receiver. In this paper, motivated by the increasing prevalence of multipacket reception (MPR) technologies such as CDMA and MIMO, we study neighbor discovery in MPR networks that allow packets from multiple simultaneous transmitters to be received successfully at a receiver. Starting with a clique of n nodes, we first analyze a simple Aloha-like algorithm and show that it takes Θ((n ln n)/k) time to discover all neighbors with high probability when allowing up to k simultaneous transmissions. We then design two adaptive neighbor discovery algorithms that dynamically adjust the transmission probability for each node. We show that the adaptive algorithms yield a Θ(ln n) improvement over the Aloha-like scheme for a clique with n nodes and are thus order-optimal. Finally, we analyze our algorithms in a general multi-hop network setting. We show an upper bound of O((Δ ln n)/k) for the Aloha-like algorithm when the maximum node degree is Δ, which is at most a factor ln n worse than the optimal. In addition, when Δ is large, we show that the adaptive algorithms are orderoptimal, i.e., have a running time of O(Δ/k) which matches the lower bound for the problem.

Performance Analysis of an Hybrid ARQ Adaptation of NDMA Schemes

Traditionally, an unsuccessful packet reception, either due to channel conditions or interference from multiple sources (collisions), is discarded and followed by a new reception of the same packet. Network diversity multiple access (NDMA) handles collisions by using time diversity multipacket reception: the base station forces terminals to transmit P copies of each packet when P terminals collide. This rigidity of having P copies is unsuitable for poor propagation conditions. It might be desirable to have more than P copies of a given packet, adopting a technique for single packet reception called hybrid-ARQ. Hybrid-ARQ effectively decreases the packet error rate. This paper proposes such mechanism for multi-packet reception, called hybrid-ARQ NDMA (H-NDMA), a gated slotted random access protocol, where the access mechanism forces the terminals involved in a collision with reception errors to transmit more than P times. Analytical models for the throughput, delay and energy per useful packet are proposed. The energy performance is analyzed for bounded average delay constraints. The proposed system's performance is evaluated for a single-carrier with frequency domain equalization (SC-FDE) scheme, and compared with the classical NDMA protocol. The comparison highlights that H- NDMA is scalable for an increasing number of terminals and network load.

On the (n, m, k)-cast capacity of wireless ad hoc networks

The capacity of wireless ad-hoc networks is analyzed for all kinds of information dissemination based on single and multiple packet reception schemes under the physical model. To represent the general information dissemination scheme, we use (n, m, k)-cast model [1] where n, to, and k (k ≤ m) are the number of nodes, destinations and closest destinations that actually receive packets from the source in each (n, m, k)-cast group, respectively. We first consider point-to-point communication, which implies single packet reception between transmitter-receiver pairs and compute the (n, m, k)-cast communications. Next, the achievable throughput capacity is computed when receiver nodes are endowed with multipacket reception (MPR) capability. We adopt maximum likelihood decoding (MLD) and successive interference cancellation as optimal and suboptimal decoding schemes for MPR. We also demonstrate that physical and protocol models for MPR render the same capacity when we utilize MLD for decoding.

Fundamental limits of information dissemination in wireless ad hoc networks-part I: single-packet reception

We present the first unified modeling framework for the computation of the capacity-delay tradeoff of random wireless ad hoc networks. This framework considers information dissemination by means of unicast routing, multicast routing, broadcasting, or different forms of anycasting. We introduce (n, m, k) -casting as a generalization of all forms of one-toone, one-to-many, and many-to-many information dissemination in wireless networks. In this context, n, m, and k denote the total number of nodes in the network, the number of destinations for each communication group, and the actual number of communication-group members that receive information (k ¿ m), respectively. We describe the capacity-delay tradeoff for (n, m, k) -casting in wireless ad hoc networks in which receivers perform single-packet reception (SPR). Our results are consistent with prior results in wireless networks and extend them to the general (n,m,k) -cast case.

Optimal unicast capacity of random geometric graphs: impact of multipacket transmission and reception

We establish a tight max-flow min-cut theorem for multi-commodity routing in random geometric graphs. We show that, as the number of nodes in the network n tends to infinity, the maximum concurrent flow (MCF) and the minimum cut-sparsity scale as ¿(n <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> r <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> (n)/k), for a random choice of k = ¿(n) source-destination pairs, where n and r(n) are the number of nodes and the communication range in the network respectively. The MCF equals the interference-free capacity of an ad-hoc network. We exploit this fact to develop novel graph theoretic techniques that can be used to deduce tight order bounds on the capacity of ad-hoc networks. We generalize all existing capacity results reported to date by showing that the per-commodity capacity of the network scales as ¿(1/r(n)k) for the single-packet reception model suggested by Gupta and Kumar, and as ¿(nr(n)/k) for the multiple-packet reception model suggested by others. More importantly, we show that, if the nodes in the network are capable of (perfect) multiple-packet transmission (MPT) and reception (MPR), then it is feasible to achieve the optimal scaling of ¿(n <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> r <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> (n)/k), despite the presence of interference. In comparison to the Gupta-Kumar model, the realization of MPT and MPR may require the deployment of a large number of antennas at each node or bandwidth expansion. Nevertheless, in stark contrast to the existing literature, our analysis presents the possibility of actually increasing the capacity of ad-hoc networks with n even while the communication range tends to zero!

First Passage Time Analysis in Wireless Sensor Networks for SPR and MPR Systems

In this paper, we study the performance of Slotted ALOHA in an elementary process in wireless sensor networks, in which sensors are activated by rare events and transmit packets to a single sink node within single hop. The time cost of the process can be viewed as a first passage time and we give the expectation of time and energy cost which is dependent on both the size of active nodes and their transmission rate by a first passage time analysis. Meanwhile, given the size of active nodes n, we demonstrated that the optimal transmission rate λmin(n) by which the first passage time attains its minimum, is nearly $${\sqrt{\log n}/n}$$. Our result indicates that time cost of the process in which each node transmits packet with transmission rate λmin(n) increases nearly linearly with n increasing. We present the maximum likelihood estimate (MLE) of the size of active nodes from the viewpoint of sink nodes so that activated nodes can adjust its transmission rate to improve the performance of the process. Energy dissipation and time cost of the procedure in the channel model of Multi Packet Reception (MPR) are considered also. Numerical results indicate that both time cost and energy consumption of the procedure in MPR channel is superior to that in Single Packet Reception (SPR) channel while the transmission rate near or less than the optimal values with which time costs attain their minimum. Otherwise the energy dissipation in MPR channel is more than that in SPR channel although comparison of time cost in the above two channels reveals the superiority of MPR channel.