Multi-channel Wireless Networks Research Articles

A Reservation Protocol Analysis for Multi-Channel Wireless Networks

A synchronous multi-channel multi-access Medium Access Control (MAC) protocol for Wireless Local Area Networks (WLANs) is studied in this paper. The proposed protocol introduces an access control reservation scheme and requires a single radio per station. The receiver collisionsphenomenon characterizes the performance of the proposedmulti-channel system. A priority scheme is considered in order to primary serve the time-sensitive traffic such as voice, as compared to the delay tolerant data traffic. The innovation of this paper is the extensive and accurate study of the receiver collisions effect on the network performance in multi-traffic environment. An analytic discrete time Markovian model is developed for finite number of stations and channels. The performance measures of throughput, delay, and average rejection probability at destination are analytically estimated. Numerical results are presented for comparison for various numbers of channels and stations. The proposed MAC protocol provides a substantial contribution to the understanding of wireless multi-channel multi-traffic environments.

Joint scheduling of data transmission and wireless power transfer in multi-channel device-to-device networks

As the mobile traffic explodes, direct device-to-device communications attract much attention as one of next-generation technologies to increase the spatial spectrum efficiency in multichannel wireless networks. On the other hand, as battery-powered mobile devices interrupt user experience due to limited battery capacity, wireless power transfer has emerged as a convenient and perpetual power supply. However, current circuit technologies cannot support both energy harvesting and information decoding at the same time, and thus the time-division-multiple-access approach is often used for either data transmission or power transfer at a time, which requires joint scheduling of data transmissions and wireless power transfer. In this paper, we investigate the joint scheduling problem of multi-channel data transmissions and wireless power transfer, formulate the joint problem using a unified framework, and identify new difficulties in efficient resource allocation. We also develop a preliminary solution that achieves good empirical performance in single-hop D2D network scenarios.

Delay constraint energy efficient broadcasting in heterogeneous MRMC wireless networks

Energy efficient broadcasting is a critical problem in Multi-Radio Multi-Channel (MRMC) wireless networks and has captured tremendous attention in the past decades. Most existing works try to minimize energy consumption in broadcast by simply minimizing the number of transmissions. However, radios and channels in MRMC wireless networks may have different propagation characteristics, e.g., communication range and energy consumption. Since wireless radios with different communication ranges have different energy consumptions, it is not always true that minimizing the number of transmissions can minimize the energy consumption. Meanwhile, more and more applications require end-to-end delay guarantee to provide Quality of Service (QoS), e.g., wireless video and online games. It is essential to satisfy the delay constraint when broadcasting in MRMC wireless networks as well.In this paper, we investigate the Delay Constraint Minimum Energy Broadcasting (DCMEB) problem in heterogeneous MRMC wireless networks. Especially, we consider heterogeneous radios and channels with different communication ranges and energy consumptions. We present an Energy Efficient Broadcasting (EEB) strategy in this work. EEB utilizes Multi-Dimension Conflict Graph (MDCG) to capture the conflicts among all possible forwarding nodes and channels, and then calculates the schedule to maximize the number of concurrent transmissions in each time slot in a cost effective way without violating the delay constraint. Our evaluation results show that EEB outperforms the state-of-the-art methods in terms of broadcasting energy cost under delay constraint in heterogeneous MRMC networks.

Throughput-Delay Trade-off Scheduling in Multi-channel Downlink Wireless Networks

This paper designs a down-link resource scheduling algorithm for wireless cellular networks to achieve throughput-delay trade-off. The available bandwidth of the down-link is divided into some parallel sub-channels, and each sub-channel can be allocated to one potential user in every time-slot. This problem is modeled as a multi-user multi-server discrete-time queuing system with a time-varying connectivity. For this system, it is well-known that the classical MaxWeight algorithm has the optimal throughput, but its delay performance is very poor. To overcome this issue, we use the Lyapunov Optimization technique to design a throughput-utility maximizing algorithm that provides a good trade-off between the throughput and delay performance. Our approach is verified by both theoretical analysis and simulation evaluations.

Toward Optimal Distributed Monitoring of Multi-Channel Wireless Networks

This paper studies an optimal channel assignment problem for passive monitoring in multi-channel wireless networks, where a set of sniffers capture and analyze the network traffic to monitor the wireless network. The objective of this problem is to maximize the total amount of traffic captured by sniffers by judiciously assigning the radios of sniffers to a set of channels. This problem is NP-hard, with the computational complexity growing exponentially with the number of sniffers. We develop distributed online solutions for large-scale and dynamic networks. The dynamism in the network may arise from mobility of the nodes being monitored. Our algorithm is guaranteed to achieve at least $1 - \frac{1}{e}$ times the optimum, regardless of the network topology and the channel assignment of nodes to be monitored, while providing a distributed solution amenable to online implementation. Further, our algorithm is cost-effective, in terms of communication and computational overheads, due to the use of purely local communication and the incremental adaptation to network changes. We present two operational modes of our algorithm for two types of networks that change at different rates; one is a proactive mode for fast-varying networks, while the other is a reactive mode for slowly-varying networks. Simulation results demonstrate the effectiveness of the two modes of our algorithm and compare it to the theoretically optimal algorithm.

A Distributed Opportunistic MAC Protocol for Multichannel Wireless Networks

We propose a distributed opportunistic medium access control (MAC) scheme for maximizing the expected aggregate throughput in a multichannel wireless network such as a clustered orthogonal frequency-division multiple access (OFDMA) network. In our proposed scheme, each user attempts to send only on its best channel and transmits if the best-channel gain is higher than a given threshold, which is dynamically updated depending on previous idle and collision situations. In this way, with our proposed scheme, in a homogeneous system where the channel fading distribution is identical for all users, the best user for each channel is obtained in a distributed manner. We also obtain the optimal values of the thresholds so that the probability of successful transmission is maximized and a minimal number of transmission opportunities are wasted (e.g., due to collision or idle transmissions). In the asymptotic limit of a large number of users and sufficiently long transmission slot duration, we show that, in comparison with the optimal centralized scheme, the throughput loss for our proposed scheme goes to zero. Furthermore, we extend our distributed opportunistic MAC scheme for a homogeneous system to that for a heterogeneous system where the channel fading distribution is heterogeneous across users. Throughput performances and signaling overhead are analyzed for the proposed distributed MAC schemes and compared with those of the existing schemes. Simulation results show that our proposed schemes significantly improve the average aggregate throughput when compared with the existing schemes.

Distributed Joint Rate Control, Resource Allocation, and Congestion Control for Throughput Optimization in Multirate Multiradio Multichannel Wireless Network with Intersession/Intrasession Network Coding

Wireless multihop networks are increasingly used because of their low cost and easy deployment. However, there are still many restrictions that degrade performance. Network coding has been proposed to improve the throughput of a wireless network through the characteristics of overhearing and broadcast. In this paper, we model the network utility maximization problem using a combined intrasession and intersession network coding method to improve the network utility in multiradio, multichannel, and multirate wireless network. And we propose a network throughput optimization scheme with a rate control, resource allocation and congestion control algorithm. We formulate an optimal framework reflecting wireless network environment. Also, we propose a rate selection scheme to choose the transmission rate on each node. We evaluate the proposed algorithms by simulation. The performance evaluation results show that the proposed scheme can improve throughput for network by utility optimization in a multiradio, multichannel, and multirate wireless network.

Exploiting Overlapped Bands for Efficient Broadcast in Multi-channel Wireless Networks

In wireless networks, broadcasting is a fundamental communication primitive for network management and information sharing. However, in multichannel networks, broadcast efficiency is very poor as devices are distributed across various channels. Thus, a sender tries all channels to broadcast a single message, causing large overhead. In this paper, we propose a novel, drastically different scheme for efficient broadcast in multichannel networks. Our scheme leverages an overlapped band of adjacent channels, which is the frequency range that partially overlapped channels share within their channel boundaries. Specifically, a sender advertises a rendezvous channel through the overlapped band of adjacent channels; message sharing is done on the rendezvous channel. Our scheme employs signaling via overlapped band (SOB), which defines a new signal processing mechanism for communication via the overlapped band. SOB is integrated with the following Multiple Access Control (MAC) layer mechanisms: 1) Reserve idle spectrum fragment to reduce waiting time, 2) multisender agreement on rendezvous channel to support multisender broadcasts, and 3) reinforce switch notification to reduce the residing time at a wrong channel. Our scheme can also be integrated with two remarkably simple but efficient mechanisms for improving the packet delivery ratio and reducing delay in a multiple contention domain. We implemented our scheme on the SORA software radio platform. Experimental results validated communication through the overlapped band. Intensive simulation studies showed that our scheme dramatically outperformed a previous approach.

On Capacity and Delay of Multichannel Wireless Networks With Infrastructure Support

In this paper, we propose a novel multi-channel network with infrastructure support, called an MC-IS network, which has not been studied in the literature. To the best of our knowledge, we are the first to study such an MC-IS network. Our proposed MC-IS network has a number of advantages over three existing conventional networks, namely a single-channel wireless ad hoc network (called an SC-AH network), a multi-channel wireless ad hoc network (called an MC-AH network) and a single-channel network with infrastructure support (called an SC-IS network). In particular, the network capacity of our proposed MC-IS network is $\sqrt{n \log n}$ times higher than that of an SC-AH network and an MC-AH network and the same as that of an SC-IS network, where $n$ is the number of nodes in the network. The average delay of our MC-IS network is $\sqrt{\log n/n}$ times lower than that of an SC-AH network and an MC-AH network, and $\min\{C_I,m\}$ times lower than the average delay of an SC-IS network, where $C_I$ and $m$ denote the number of channels dedicated for infrastructure communications and the number of interfaces mounted at each infrastructure node, respectively. Our analysis on an MC-IS network equipped with omni-directional antennas only has been extended to an MC-IS network equipped with directional antennas only, which are named as an MC-IS-DA network. We show that an MC-IS-DA network has an even lower delay of $\frac{c}{\lfloor \frac{2\pi}{\theta}\rfloor \cdot C_I}$ compared with an SC-IS network and our MC-IS network. For example, when $C_I=12$ and $\theta=\frac{\pi}{12}$, an MC-IS-DA network can further reduce the delay by 24 times lower that of an MC-IS network and reduce the delay by 288 times lower than that of an SC-IS network.

Performance Evaluation of Multi-Channel Wireless Backoff Algorithm

Wireless technologies are the critical components that facilitate ubiquitous communications among users, devices, and humans-machines. IEEE 802.11 is a popular wireless access technology which uses a truncated binary exponential backoff algorithm in a shared channel. But its performance deteriorates rapidly if there are numerous simultaneous active connections. Multi-channel wireless network, consisting of control and data channels, is one possible solution to offer sustainable high performance large-scale networks. In this letter, we analyze the performance of a multi-channel backoff (MCB) algorithm, which gives a non-zero performance bound for large network sizes. Through simulations and analysis, settings of associated system parameters are determined to offer high goodput performance.

MaxWeight Versus BackPressure: Routing and Scheduling in Multichannel Relay Networks

We study routing and scheduling algorithms for relay-assisted, multichannel downlink wireless networks [e.g., orthogonal frequency-division multiplexing (OFDM)-based cellular systems with relays]. Over such networks, while it is well understood that the BackPressure algorithm is stabilizing (i.e., queue lengths do not become arbitrarily large), its performance (e.g., delay, buffer usage) can be poor. In this paper, we study an alternative--the MaxWeight algorithm--variants of which are known to have good performance in a single-hop setting. In a general relay setting, however, MaxWeight is not even stabilizing (and thus can have very poor performance). In this paper, we study an iterative MaxWeight algorithm for routing and scheduling in downlink multichannel relay networks. We show that, surprisingly, the iterative MaxWeight algorithm can stabilize the system in several large-scale instantiations of this setting (e.g., general arrivals with full-duplex relays, bounded arrivals with half-duplex relays). Furthermore, using both many-channel large-deviations analysis and simulations, we show that iterative MaxWeight outperforms the BackPressure algorithm from a queue-length/delay perspective.

Random Node Failures and Wireless Networks Connectivity: Theoretical Analysis

Multi-radio multi-channel wireless networks (M 2WNs) have been studied intensively over the past decade with focusing on traffic management functionalities such as channel-to-interface assignment, traffic routing and scheduling. These developed solutions always assumed continuous normal operation of all network components while failing to take into considering the failure-prone nature of wireless networks. This article analyzes the effects of node failure on the ability of network nodes to maintain their connectivity. More precisely, we present a tight upper bound on the node failure probabilities needed to maintain full network connectivity on the one hand. On the other hand, a lower bound, at which the system loses connectivity, is also derived. We show that these bounds are dependent only on the nodes' geometric distribution and density. We then verify these theoretical results against those obtained via experimentation.

SybilCast

Consider a scenario where many wireless users are attempting to download data from a single base station. While most of the users are honest, some users may be malicious and attempt to obtain more than their fair share of the bandwidth. One possible strategy for attacking the system is to simulate multiple fake identities, each of which is given its own equal share of the bandwidth. Such an attack is often referred to as a sybil attack . To counter such behavior, we propose SybilCast , a protocol for multichannel wireless networks that limits the number of fake identities and, in doing so, ensures that each honest user gets at least a constant fraction of his or her fair share of the bandwidth. As a result, each honest user can complete his or her data download in asymptotically optimal time. A key aspect of this protocol is balancing the rate at which new identities are admitted and the maximum number of fake identities that can coexist while keeping the overhead low. Besides sybil attacks, our protocol can also tolerate spoofing and jamming.

Cooperative packet-forwarding mechanism for throughput improvement in multi-channel wireless networks

Typical MAC protocols for IEEE 802.11-based ad hoc networks employ a direct transmission strategy whenever the transmitter can directly reach the receiver (one-hop transmission). While such a design enjoys simplicity, it limits the number of admitted transmissions in a given neighborhood. Due to the performance anomaly of 802.11-based wireless networks, transmission with low data rates occupy the shared medium for longer periods of time. Occupying the transmission medium for a longer period of time results in less available transmission time for other nodes, which consequently reduces the number of transmitted packets during the same period of time, leading to a reduction in network throughput. To improve the overall network throughput, we present a cooperative multi-channel MAC protocol for single-hop wireless mobile ad hoc networks that attempts at computing the path with the minimum required transmission time for a given source–destination pair (including the channel assignment along that path). The proposed protocol attempts at improving network performance by means of cooperative communications. According to our approach, if the one-hop (direct) path between communicating nodes supports low data rate (requires longer transmission time), the source selects a multi-hop path to the destination such that the total amount of required transmission time is minimized. Through simulations, we show that our proposed protocol achieves significant throughput and fairness improvement compared to the standard IEEE 802.11-based protocol.

A Systematic Study of Maximal Scheduling Algorithms in Multiradio Multichannel Wireless Networks

The greedy maximal scheduling (GMS) and maximal scheduling (MS) algorithms are well-known low-complexity scheduling policies with guaranteed capacity region in the context of single-radio single-channel (SR-SC) wireless networks. However, how to design maximal scheduling algorithms for multiradio multichannel (MR-MC) wireless networks and the associated capacity analysis are not well understood yet. In this paper, we develop a new model by transforming an MR-MC network node to multiple node-radio-channel (NRC) tuples. Such a framework facilitates the derivation of a tuple-based back-pressure algorithm for throughput-optimal control in MR-MC wireless networks and enables the tuple-based GMS and MS scheduling as low-complexity approximation algorithms with guaranteed performance. An important existing work on GMS and MS for MR-MC networks is that of Lin and Rasool (IEEE/ACM Trans. Networking, vol. 17, no. 6, 1874--1887, Dec. 2009), where link-based algorithms are developed. Compared to the link-based algorithms, the tuple-based modeling has significant advantages in enabling a fully decomposable cross-layer control framework. Another theoretical contribution in this paper is that we, for the first time, extend the local-pooling factor analysis to study the capacity efficiency ratio of the tuple-based GMS in MR-MC networks and obtain a lower bound that is much tighter than those known in the literature. Moreover, we analyze the communications and computation overhead in implementing the distributed MS algorithm and present simulation results to demonstrate the performance of the tuple-based maximal scheduling algorithms.

Achieving Optimal Throughput and Near-Optimal Asymptotic Delay Performance in Multichannel Wireless Networks With Low Complexity: A Practical Greedy Scheduling Policy

In this paper, we focus on the scheduling problem in multi-channel wireless networks, e.g., the downlink of a single cell in fourth generation (4G) OFDM-based cellular networks. Our goal is to design practical scheduling policies that can achieve provably good performance in terms of both throughput and delay, at a low complexity. While a class of $O(n^{2.5} \log n)$-complexity hybrid scheduling policies are recently developed to guarantee both rate-function delay optimality (in the many-channel many-user asymptotic regime) and throughput optimality (in the general non-asymptotic setting), their practical complexity is typically high. To address this issue, we develop a simple greedy policy called Delay-based Server-Side-Greedy (D-SSG) with a \lower complexity $2n^2+2n$, and rigorously prove that D-SSG not only achieves throughput optimality, but also guarantees near-optimal asymptotic delay performance. Specifically, we show that the rate-function attained by D-SSG for any delay-violation threshold $b$, is no smaller than the maximum achievable rate-function by any scheduling policy for threshold $b-1$. Thus, we are able to achieve a reduction in complexity (from $O(n^{2.5} \log n)$ of the hybrid policies to $2n^2 + 2n$) with a minimal drop in the delay performance. More importantly, in practice, D-SSG generally has a substantially lower complexity than the hybrid policies that typically have a large constant factor hidden in the $O(\cdot)$ notation. Finally, we conduct numerical simulations to validate our theoretical results in various scenarios. The simulation results show that D-SSG not only guarantees a near-optimal rate-function, but also empirically is virtually indistinguishable from delay-optimal policies.

Performance Evaluation of Efficient Scheduling Algorithms for Achieving Optimal Flow Delay and to Enhance Throughput in Multichannel Wireless Networks

Performance Evaluation of Efficient Scheduling Algorithms for Achieving Optimal Flow Delay and to Enhance Throughput in Multichannel Wireless Networks

Routing, spectrum access, and scheduling in multi-hop multi-channel wireless networks with MIMO links

Software-defined radios (SDRs) are a promising technology to enable dynamic channel access and sharing. Multiple Input Multiple Output (MIMO) is another radio technology breakthrough for increasing wireless network capacity. To obtain the full benefits brought by the SDR and MIMO technologies in wireless mesh networks (WMNs), the higher layer mechanisms should exploit their capabilities in a systematic way. In this paper, we investigate routing, channel assignment, link scheduling, and MIMO transmission mode control in multi-channel multi-antenna wireless mesh networks. We first present a cross-layer framework for network performance optimization. Network traffic routing is established on a relatively long time scale to maintain system stability. We then proposed a stream controlled multiple access (SCMA) scheme, which is responsible for assigning frequency channels and scheduling links for data transmission and controlling MIMO transmission modes. It enables efficient spectrum access and sharing in time, frequency, and space, and adapts to varying network conditions. The evaluation results show that the proposed scheme greatly improves network performance compared to the traditional schemes.

Joint link rate allocation, routing and channel assignment in multi-rate multi-channel wireless networks

In this paper we address the issue of joint routing, channel assignment, scheduling and link rate allocation in multi-rate multi-channel wireless networks with the goal of increasing network capacity. Many wireless standards support a variety of modulation and coding schemes, which allow devices to choose from several transmission rates. Typically, the highest possible rate is used for transmission, but the potential for increased spatial reuse and capacity exists when using lower rates due to higher interference tolerance. This problem of selecting link rates is further complicated in a multi-channel network. Channel assignment affects the sets of interfering links, and as such also influences the optimal choice of link rates. And there is also an interdependency between routing and both rate and channel assignment. In this work we analyze the joint problem and, due to its hardness, propose a fast heuristic algorithm (JMR) to solve it. We evaluate this algorithm through numerical experiments in a wide variety of configurations, showing that potential for improved capacity via link rate allocation depends on a variety of factors which relate to the capability and need of exploiting spatial reuse, and which include the transmission power, the number of channels and the network architecture and topology. In this work we also propose an architecture for wireless mesh networks with increased capacity and under which optimized rate allocation is shown to notably increase performance. Finally, we evaluate the solutions found by JMR under the ns-3 simulator using the 802.11a protocol stack, where it is shown that physical and MAC layer limitations reduce the performance gain of JMR.

A Distributed Approach to Construct Minimum Spanning Tree in Cognitive Radio Networks

Abstract The minimum spanning tree is useful for data disseminating or broadcasting where a leader node can regulate the data with minimum cost and time. The article presents an algorithm to construct minimum spanning tree in cognitive radio networks. The cognitive radio network works differently with single channel or multi-channel wireless networks than conventional wireless networks. The cognitive radio (or secondary user) nodes have multi-channel accessing capabilities during run time by adjusting the radio parameters according to the available spectrum. The primary user or licensed user holds the spectrum and if it is free, the secondary user can use this for any purpose. Initially, we identify the challenges related to formation of logical structure in cognitive radio network. Then, we present our time and message constrained based cost (or weight) estimation distributed algorithm to construct minimum spanning tree. We describe our algorithm with the help of state diagram representation. The correctness proof of the algorithm is also included.