Scheduling and power control for MAC layer design in multihop IR‐UWB networks

Recently, a number of researchers have proposed media access control (MAC) designs for ultra‐wideband (UWB) networks. Among them, designs based on scheduling and power control seem to be of great promise, particularly for quality‐of‐service (QoS) traffic. We investigate the efficiencies of many different choices for scheduling and power allocation for QoS traffic in a multihop impulse radio (IR)‐UWB network, with the objective of achieving both high spectral efficiency and low transmission power. Specifically, we compare different scheduling schemes employing a protocol interference‐based contention graph as well as a physical interference‐based contention graph. We propose a relative distance to determine adjacency in the protocol interference‐based contention graph. Using our improved protocol interference model with graph‐based scheduling, we obtained better performance than the physical interference‐based approach employing link‐by‐link scheduling. Copyright © 2009 John Wiley & Sons, Ltd.     

A novel QoS‐aware MAC protocol for voice services over IEEE 802.11‐based WLANs

With the pervasive growth in the popularity of IEEE 802.11‐based wireless local area networks (WLANs) worldwide, the demand to support delay‐sensitive services such as voice has increased very rapidly. This paper provides a comprehensive survey on the medium access control (MAC) architectures and quality of service (QoS) provisioning issues for WLANs. The major challenges in providing QoS to voice services through WLAN MAC protocols are outlined and the solution approaches proposed in the literature are reviewed. To this end, a novel QoS‐aware wireless MAC protocol, called hybrid contention‐free access (H‐CFA) protocol and a call admission control technique, called traffic stream admission control (TS‐AC) algorithm, are presented. The H‐CFA protocol is based on a novel idea that combines two contention‐free wireless medium access approaches, that is, round‐robin polling and time‐division multiple access (TDMA)‐like time slot assignment, and it increases the capacity of WLANs through efficient silence suppression. The TS‐AC algorithm ensures efficient admission control for consistent delay‐bound guarantees and further maximizes the capacity through exploiting the voice characteristic that it can tolerate some level of inconsecutive packet loss. The benefits of the proposed schemes are demonstrated in the simulations results. Copyright © 2008 John Wiley & Sons, Ltd.     

MAC Protocol Design and Optimization for Multi-Hop Ultra-Wideband Networks

Ultra-wideband (UWB) communication is a promising enabling technology for future broadband wireless services. A simple, scalable, distributed, efficient medium access control (MAC) protocol is of critical importance to utilize the large bandwidth UWB channels and enable numerous new applications and services cost-effectively. In this paper, by investigating the characteristics of UWB communications, we propose a Distributed, EXclusive region (DEX) based MAC protocol. The proposed DEX protocol capitalizes on the spatial multiplexing gain of UWB networks by reserving exclusive regions (ER) surrounding the sender and receiver for data and acknowledgment (ACK) transmissions, so that users can efficiently and fairly share network resources in a distributed and asynchronous manner. We further quantify the network performance bounds and derive the optimal ER size to maximize the expected network transport throughput for a dense, multi-hop UWB network. Extensive simulation results demonstrate the efficiency and effectiveness of the DEX protocol. This work explores how to effectively utilize the wireless spatial capacity of distributed, multi-hop wireless networks by optimizing protocol parameters, instead of depending on more complicated control messages.     

Energy consumption of the IEEE Std 802.15.3 MAC protocol in communication link set-up over UWB radio technology

This paper examines the overhead associated with the IEEE Std 802.15.3 medium access control (MAC) protocol when used in conjunction with Ultra Wide-Band (UWB) radio technology. Particular features of the protocol examined include establishing, modifying and terminating data streams. The main focus of the paper is to investigate the overhead introduced in terms of energy consumption to manage the communication links. One of the main UWB technology candidates, Impulse-Radio (IR-UWB), utilizes very short time domain pulses which are low power and difficult to detect. This raises the question of how to design an efficient MAC protocol to harness the potential of the physical layer (PHY). For high data rate WPAN applications, the IEEE Std 802.15.3 protocol has been proposed as a suitable MAC. In the simulations the data source rate and the number of devices in the network are varied and the considerable overhead produced by command frames is observed.     

基于UWB通信系统的MAC协议研究

目前,超宽带(UWB)技术由于其特有的优点受到越来越多的关注,其中,针对于UWB系统的MAC协议的设计逐渐成为热点。与现有无线通信系统相比,UWB系统占有更宽的频带,具有更高的传输速率,发射功率谱密度非常低,因此,需要设计符合该系统特点,满足该系统节能、高吞吐量以及低时延等要求的MAC协议。文章通过对现有用于UWB通信系统的MAC协议的综合分析和比较,提出对UWB-MAC协议设计的要求。     

A novel MAC protocol for IDMA‐based multi‐beam satellite communication systems

Considering the limitations of satellite communication systems and advantages of new emerging interleave‐division multiple access (IDMA) technology, IDMA is introduced into the satellite systems, providing a new solution for multiple access techniques of satellite systems. To further validate the IDMA into satellite systems, a novel medium access control (MAC) scheme is proposed. In the random access channel, the interleave‐division slotted ALOHA method is adopted to alleviate the collision of access requests. Furthermore, a novel minimum power allocation scheme based on signal‐to‐interference‐plus‐noise ratio (SINR) evolution is proposed to maximize the capacity of such an interference‐sensitive system. By virtue of SINR evolution, our proposed scheme can accurately estimate multi‐user detection efficiency with low computational cost and further reduce the transmitted power, illustrating the high power efficiency of IDMA. To further enhance the performance of the MAC protocol, an effective call admission control scheme considering the effect of power control error is designed and combined into our MAC protocol. Analysis and simulation results show that, by taking full advantage of the chip‐by‐chip multi‐user detection technique, the proposed IDMA MAC protocol achieves high throughput and low average packet delay simultaneously, with low onboard processing complexity in the multi‐beam satellite communication systems. Copyright © 2013 John Wiley & Sons, Ltd.     

Busy tone contention protocol: a new high‐throughput and energy‐efficient wireless local area network medium access control protocol using busy tone

Design of an efficient wireless medium access control (MAC) protocol is a challenging task due to the time‐varying characteristics of wireless communication channel and different delay requirements in diverse applications. To support variable number of active stations and varying network load conditions, random access MAC protocols are employed. Existing wireless local area network (WLAN) protocol (IEEE 802.11) is found to be inefficient at high data rates because of the overhead associated with the contention resolution mechanism employed. The new amendments of IEEE 802.11 that support multimedia traffic (IEEE 802.11e) are at the expense of reduced data traffic network efficiency. In this paper, we propose a random access MAC protocol called busy tone contention protocol (BTCP) that uses out‐of‐band signals for contention resolution in WLANs. A few variants of this protocol are also proposed to meet the challenges in WLAN environments and application requirements. The proposed BTCP isolate multimedia traffics from background data transmissions and gives high throughput irrespective of the number of contending stations in the network. As a result, in BTCP, admission control of multimedia flows becomes simple and well defined. Studies of the protocol, both analytically and through simulations under various network conditions, have shown to give better performance in comparison with the IEEE 802.11 distributed coordination function. Copyright © 2011 John Wiley & Sons, Ltd.     

Radio resource sharing for ad hoc networking with UWB

Ultra-wideband (UWB) radio is becoming a promising field for new generation's digital communication systems. This technique, based mainly on the impulse radio paradigm, offers great flexibility and shows enormous potential in view of a future broadband wireless access. We present the main principles to design a multiaccess scheme based on UWB. The potential of UWB is exploited within a distributed ad hoc wireless system, where we describe the principles for the definition of a medium-access control (MAC) for mobile computing applications and we analyze the main performance results derived from simulations. A general framework for radio resource sharing is outlined for classes of traffic requiring both elastic-dynamic and guaranteed-reserved bandwidth. Then, we discuss the issue of supporting the proposed radio resource sharing scheme by means of a distributed MAC protocol.     

E‐MAC: an elastic MAC layer for IEEE 802.11 networks

We present a system for real‐time traffic support in infrastructure and ad hoc IEEE 802.11 networks. The proposed elastic MAC (E‐MAC) protocol provides a distributed transmission schedule for stations with real‐time traffic requirements, while allowing a seamless coexistence with standard IEEE 802.11 clients, protecting best‐effort 802.11 traffic from starvation by means of admission control policies. Our scheduling decisions are based on an ‘elastic’ transmission opportunity (TXOP) assignment which allows for efficient wireless resource usage: whenever a real‐time station does not use the assigned TXOP, the other real‐time stations can take over the unused access opportunity, thus preventing the well‐known inefficiencies of static time division multiple access (TDMA) schemes. Unlike other TDMA‐based solutions for 802.11, E‐MAC does not require a tight synchronization among the participating clients, thus allowing its implementation on commodity WLAN hardware via minor software changes at the client side, and no changes at the access points (APs). We studied the performance of our mechanism via ns‐2 simulations and a mathematical model, showing that it outperforms IEEE 802.11e in terms of throughput, delay, and jitter. We finally provide a proof of concept through the results obtained in a real testbed where we implemented the E‐MAC protocol. Copyright © 2011 John Wiley & Sons, Ltd.     

RPCP‐MAC: Receiver preambling with channel polling MAC protocol for underwater wireless sensor networks

To design a reliable and energy efficient medium access control (MAC) protocol for underwater wireless sensor networks (UWSNs) is an active research area due to its variety of applications. There are many issues associated with underwater acoustic channels including long and variable propagation delay, attenuation, and limited bandwidth which pose significant challenges in the design of MAC protocol. The available sender‐initiated asynchronous preamble‐based MAC protocols for UWSNs are not reliable and energy‐efficient. This is due to the problems caused by transmission of preambles for longer duration and collision of preambles from hidden nodes in sender‐initiated preamble‐based MAC protocols. To resolve these issues, the paper proposed an asynchronous receiver‐initiated preamble‐based MAC protocol named Receiver Preambling with Channel Polling MAC (RPCP‐MAC) protocol for shallow underwater monitoring applications with high data rates. The protocol is proposed to resolve data packet collision and support reliability in an energy‐efficient way without using any transmission schedule. The proposed protocol is based on the following mechanisms. Firstly, receiver preambling mechanism is adopted to reduce idle listening. Secondly, channel polling mechanism is used to determine missing data frame during its sleeping period and to minimize the active time of node and reduces energy wastage. Finally, a back‐off mechanism is applied to resolve collision when preambles are received simultaneously. In addition, performance analysis through Markov chain together with its validation with simulation‐based studies is reported in the paper. Both the analytical and simulation results have demonstrated the reliability achievable with RPCP‐MAC while providing good energy efficiency.     

A refined MAC protocol with multipacket reception for wireless networks

Medium access control (MAC) protocols making use of multipacket reception (MPR) capability achieve better throughput than conventional MAC protocols. When a wireless network operates with MPR capable nodes and non‐MPR nodes, the MAC protocols must not only utilise the MPR capability to maximise throughput, but must also enable the co‐existence with these two types of nodes. We propose a new MPR MAC protocol to achieve the co‐existence requirement by adopting a request‐to‐send (RTS)/clear‐to‐send (CTS) mechanism in IEEE 802.11 MAC standards. This MPR MAC protocol also improves throughput by allowing additional data transmissions to use the MPR capability fully. We analyse the system throughput of the co‐existence of different link characteristics of nodes, and optimise its throughput by adjusting contention window sizes with respect to certain throughput requirements of the nodes. Copyright © 2010 John Wiley & Sons, Ltd.     

Optimal transmissions for space-time coded OFDM UWB systems

1 Introduction Recently, the high rate short range wireless personal area network (WPAN) is considered. When the inverse of the sampling rate is significantly shorter than the total delay spread, as is the case for most UWB communication systems, OFDM systems are more attractive than a single-carrier system. The multi-band OFDM physical layer proposal has been adopt by IEEE 802.15.3a Task Group[1]。 Combing STC and OFDM have the properties to achieve high data rate and mitigate int…     

Analysis of a Cooperative Beacon-Free MAC Layer for Body Area Networks

This paper discusses medium access control (MAC) issues for body area networks (BANs), relying on an Ultrawide Band Impulse radio (UWB-IR) physical layer. BANs are bound to be coordinated by a powerful device like a smart-phone, which manage the access of the nodes on a beaconed fashion. But in some particular situations, the coordinator may disappear and/or be not yet available. These transient situations shall be addressed and a beacon-free medium access control is desirable. We propose a beacon-free MAC layer, based on a collaborative version of the preamble sampling approach. This is designed to address the European regulatory low duty cycle (LDC) constraint, which UWB devices must comply to. A Markov chain model is given to describe the protocol. By means of simulations, we first show that the model is accurate and secondly that this protocol looks able to manage various BANs configurations.     

Medium access control in ultra-wideband wireless networks

Ultra-wideband (UWB) transmission is an emerging wireless communication technology with unique potential merits such as high-rate, low-transmission power, immunity to multipath propagation, and capability in precise positioning. It has received significant interests for future wireless communications from both academia and industry. In UWB wireless networks, medium access control (MAC) is essential to coordinate the channel access among competing devices. The unique UWB characteristics not only pose significant challenges but also offer great opportunities in efficient UWB MAC design. This paper presents a comprehensive overview of UWB MAC development on four important aspects: multiple access, overhead reduction, resource allocation, and quality of service (QoS) provisioning, and identifies some future research issues.     

一种新型私有多信道UWB MAC协议

媒体接入控制技术的核心问题是如何协调多个用户共用一个信道实现高效可靠传输,即多址接入问题.文章提出了一种新型私有多信道UWB MAC协议.利用码字在逻辑上划分多个信道,且通过码宇与用户节点某些特定信息相联系,私有化了各个节点的控制信道和业务信道.进一步降低了系统碰撞的可能性.提高了系统吞吐量性能.     

A load awareness medium access control protocol for single‐hop wireless ad hoc networks

A contention‐based wireless ad hoc medium access control (MAC) protocol, such as carrier sense multiple access with collision avoidance (CSMA/CA), has excellent efficiency when the system is light loaded. The main drawback of such protocols is their inefficiency and unbounded delay when the system load is heavy. On the other hand, a contention‐free MAC protocol, such as token passing, has a better and fair throughput when the system is heavy loaded. The main drawback of such protocols is their inefficiency when only a small amount of users want to transmit. In this paper, we propose a new load awareness single‐hop wireless ad hoc MAC protocol (which is called the LA protocol) that exploits the benefits of both contention‐based and contention‐free protocols. A contention‐based MAC protocol is used when the system is light loaded and a contention‐free one is used otherwise. Our LA protocol, which operates in a distributed fashion and is fully compatible with the IEEE 802.11 wireless local area network (WLAN) standard, can switch smoothly between the contention‐based protocol and the contention‐free one. Simulation results show that our protocol indeed extracts the better part of two kinds of protocols. Copyright © 2006 John Wiley & Sons, Ltd.     

Virtual base stations for wireless mobile ad hoc communications: an infrastructure for the infrastructure‐less

In this paper, we propose a new protocol for wireless mobile ad hoc networks, which establishes a dynamic wireless mobile infrastructure. The proposed protocol, namely, the virtual base stations (VBS) protocol, mimics and maintains the operation of the conventional fixed infrastructure in cellular networks. In the VBS protocol, a mobile node is elected from a set of nominees to act as a temporary base station within its zone. We provide proofs for the correctness of the VBS protocol, and show lower and upper bounds for its global convergence time. Likewise, we study the characteristics and performance of VBS by means of simulation. It is shown that VBS scales well to large networks of mobile stations, and that it outperforms other infrastructure‐formation protocols in terms of stability. The VBS protocol would facilitate the development of a comprehensive and promising framework for quality of service (QoS) management in wireless mobile ad hoc networks once the proper integration of the MAC protocol with the routing and call admission control mechanisms is established. The VBS architecture lays the groundwork for assigning bandwidth, and/or implementing priorities, and hence for QoS‐based routing by conveying the quality of a path prior to call setup. Copyright © 2001 John Wiley & Sons, Ltd.     

High-capacity packet-switched optical ring network

We propose a novel architecture with MAC and admission control protocols for a high-capacity packet-switched optical ring network. In this network the link capacity significantly exceeds the node bit rate. Nodes transmit and receive packets on multiple wavelengths in parallel by using novel optical techniques. Network control is simple since the load is balanced over wavelengths at the physical layer. The MAC protocol is based on credits, and the derived admission control protocol has similar complexity as in a single channel network. Consequently, the network can follow fast traffic changes which are typical in data networks     

Multichannel medium access control for ad hoc wireless networks

In this paper, we study the multichannel exposed terminal problem in multihop wireless networks. We propose a multichannel medium access control (MAC) protocol, called multichannel MAC protocol with hopping reservation (MMAC‐HR), to resolve the multichannel exposed terminal problem. MMAC‐HR uses two radio interfaces; one interface is fixed over the control channel, and the other interface switches dynamically between data channels. The fixed interface supports broadcast information and reserves a data channel for any data transmission. The switchable interface, on other hand, is for data exchanges and follows independent slow hopping without requiring clock synchronization. In addition, the proposed protocol is a distributed one. By using the ns‐2 simulator, extensive simulations are performed to demonstrate that MMAC‐HR can enhance the network throughput and delay compared with existing multichannel MAC protocol. Copyright © 2011 John Wiley & Sons, Ltd.     

A HiperLAN II frame processor implementation

In recent years, wireless access networks offer an alternative method for connecting subscribers to the global communication network. Several high‐speed Wireless LAN's (WLAN) standards have emerged and among them the ETSI BRAN HiperLAN II standard is distinguished for its performance and QoS support. This paper, starting with a short overview of HiperLAN II main features and Medium Access (MAC) protocol, presents the architecture of an implemented high‐speed Frame Processor that realizes the medium access control (MAC) protocol of the HiperLAN II standard. The main goal of the Frame Processor is the real‐time management of the air interface as well as to bridge the upper network layers with the wireless world, relieving the data link control (DLC) layer of time‐consuming tasks such as slot map allocation extraction, bit‐by‐bit processing of data units, framing and synchronization. Copyright © 2003 John Wiley & Sons, Ltd.