Idle-signal casting multiple access with collision resolution(ICMA/CR) protocol for wireless LAN

The authors propose an idle-signal casting multiple access with collision resolution (ICMA/CR) protocol for wireless LAN. This protocol focuses on efficient collision resolution by adopting the binary-tree protocol. By using the collision resolution algorithm, the retransmission process can be controlled so that collisions are resolved more efficiently using nearly immediate feedback information, thereby increasing the throughput-delay performance of the ICMA/CD protocol     

A multiple access collision avoidance protocol for multicast services in mobile ad hoc networks

In order to improve cross-layer optimization, we propose a multiple access collision avoidance protocol that combines RTS/CTS with scheduling algorithms to support the multicast routing protocol. We avoid collision by including additional information in the RTS. The proposed scheme, together with extra benefits, such as power saving, reliable data transmission and higher channel utilization compared with CSMA or multiple unicast, enables the support of multicast services in mobile ad hoc networks.     

Fixed collision rate back-off scheme for collision resolution in wireless networks

This investigation proposes a fixed collision rate (FCR) back-off algorithm for wireless networks. The proposed scheme takes advantage of the central unit (CU) in a wireless network to broadcast a common back-off window size to all the users, significantly alleviating the unfairness of bandwidth utilization in conventional binary exponential back-off (BEB) algorithms. It is shown that, when maximum throughput is achieved, collision rate is almost a constant for any traffic load. In the operation of the FCR, the CU dynamically adjusts the back-off window size to keep the collision rate at a constant level for maximum throughput. Simulation results demonstrate that the unfairness of bandwidth utilization in the BEB is significantly lessened and the throughput can be maintained at e^-1≈0.368 when the number of users approaches infinity. The capture effect even further improves system performance.     

A practical authentication protocol with anonymity for wireless access networks

The use of anonymous channel tickets was proposed for authentication in wireless environments to provide user anonymity and to probably reduce the overhead of re‐authentications. Recently, Yang et al. proposed a secure and efficient authentication protocol for anonymous channel in wireless systems without employing asymmetric cryptosystems. In this paper, we will show that Yang et al.'s scheme is vulnerable to guessing attacks performed by malicious visited networks, which can easily obtain the secret keys of the users. We propose a new practical authentication scheme not only reserving the merits of Yang et al.'s scheme, but also extending some additional merits including: no verification table in the home network, free of time synchronization between mobile stations and visited networks, and without obsolete anonymous tickets left in visited networks. The proposed scheme is developed based on a secure one‐way hash function and simple operations, a feature which is extremely fit for mobile devices. We provide the soundness of the authentication protocol by using VO logic. Copyright © 2010 John Wiley & Sons, Ltd.     

Quasi-FIFO back-off scheme for collision resolution in wireless networks

This paper proposes a quasi-FIFO (QFIFO) back-off scheme for collision resolution in wireless networks. The proposed scheme takes advantage of the central unit (CU) in a wireless network to broadcast a common back-off window size to all the users, significantly alleviating the unfairness of bandwidth utilization in conventional binary exponential back-off (BEB) schemes. Since the maximum throughput is achieved when the back-off window size equals the number of users, the average number of users involved in each collision slot is derived to estimate the number of simultaneously competing users. In the QFIFO scheme, service time is divided into a series of cycles. Packets arrive in the current cycle are guaranteed to be serviced prior to any packet generated in the next cycle and the first-in-first-out (FIFO) principle can thus be semi-accomplished. Simulation results demonstrate that the unfairness of bandwidth utilization in the BEB is significantly mitigated and the throughput can be maintained at 0.368 when the number of users approaches infinity. The capture effect even further improves system performance.     

基于多信道预约可冲突避免的多址接入协议

本文为多跳分布多无线网络提出了一套灵活而有效的自适应获取冲突避免（AACA）的多址接入协议。在该协议中，各节点竞争公共信道，利用RTS/CTS对话形式来预约各业务信道，成功预约后的分组传输不会受到其他节点的干扰。它使用任意确定数目信道，以异步方式工作，并且使得各节点利用半双工无线电台就可以灵活、简便地实现资源预约。分析和比较结果说明，所提出的多信道预约协议可以有效地解决隐藏终端、暴露终端以及侵入终端的问题。     

ARCMA—adaptive request channel multiple access protocol for wireless ATM networks

We propose a new multiple access protocol based on demand assignment. This protocol is designed to reduce contention in the request phase while minimizing transmission delay under various network (ATM) environments. Our protocol uses an adaptive scheme that changes under heavy traffic conditions, and also provides priority to certain delay‐sensitive traffic. Copyright © 2001 John Wiley & Sons, Ltd.     

An efficient demand-assignment multiple access protocol for wireless packet (ATM) networks

In a wireless packet (ATM) network that supports an integrated mix of multimedia traffic, the channel access protocol needs to be designed such that mobiles share the limited communications bandwidth in an efficient manner: maximizing the utilization of the frequency spectrum and minimizing the delay experienced by mobiles. In this paper, we propose and study an efficient demand-assignment channel access protocol, which we call Distributed-Queueing Request Update Multiple Access (DQRUMA). The protocol can be used for a wide range of applications and geographic distances. Mobiles need to send requests to the base station only for packets that arrive to an empty buffer. For packets that arrive to a non-empty buffer, transmission requests are placed collision-free by piggybacking the requests with packet transmissions. The simulation results show that even with the worst possible traffic characteristics, the delay-throughput performance of DQRUMA is close to the best possible with any access protocol. In addition, explicit slot-by-slot announcement of the transmit permissions gives the base station complete control over the order in which mobiles transmit their packets. This important feature helps the base station satisfy diverse Quality-of-Service (QoS) requirements in a wireless ATM network.     

Hierarchy schedule-sensing protocol for CDMA wireless data-centric networks with multiple packet collision and capture effect

This paper focuses on performance analysis of a CDMA wireless data network based on hierarchy schedule-sensing (HSS) protocol, in which a common-code permission frame beacon is used to schedule request transmissions to avoid packet collisions. To further reduce scheduling delay, hierarchical group-based coding is adopted in the scheme. The performance of such a network is evaluated considering packet collisions with and without packet capture effect using a two-dimensional Markovian chain model. In particular, this paper will study the impact of multiple packet-collision effect on network performance with the help of the average packet-collision rate derived explicitly in the paper. The obtained results show that, despite its low implementation complexity, the HSS protocol is a fairly robust medium-access control protocol featuring uniformly high throughput and short delay even under very high traffic load, which especially suits data-centric wireless networks with relatively small coverage area and great node density.     

Semi-blind collision resolution in random access wireless ad hocnetworks

A new signal processing based collision resolution technique for random access wireless ad hoc networks is proposed. Without assuming the knowledge of the propagation channels and signal waveforms, the proposed algorithm is capable of separating colliding packets by exploiting channel diversities and known symbols embedded in data packets. Compared with training-based methods, the proposed algorithm requires considerably fewer known symbols. This algorithm can be applied to various spread spectrum and narrowband systems along with existing medium access control protocols     

Mobility-aware timeout medium access control protocol for wireless sensor networks

Wireless sensor networks (WSNs), has been under development for a while by the academia and industry. Due to limited computational power, a typical sensor node may experience operational challenges. Moreover, mobility has become an important feature since emergency and healthcare related applications are evolving in WSNs. Consideration of mobile nodes in WSNs introduce new challenges for the designers. In this paper, an enhanced version of T-MAC protocol (a well-known medium access control protocol in WSNs) known as MT-MAC is proposed. Using the capturing fluctuation in RSSI and LQI values of the received SYNC packets, MT-MAC solves high packet drop ratio in T-MAC. By detecting the mobility, a mobile node softly handover to a new virtual cluster without losing connection with other nodes. The performance of the proposed solution is then compared with T-MAC, S-MAC as well as other well-known mobility-aware MAC (MS-MAC) protocol. The simulation results show that the proposed protocol significantly increases the throughput and packet delivery ratio of T-MAC in exchange for a small increase in power consumption. Compared to MS-MAC protocol, the proposed approach can reduce power consumption by 20–65%, and achieve slightly higher packet delivery ratio.     

Hidden node collision recovery protocol for low rate wireless personal area networks

Referring to most media access control (MAC) protocols in low rate personal area networks (LR‐WPANs), there is no hidden node collision avoidance mechanism utilized. Quantitative analysis in this paper based on the IEEE 802.15.4 specification shows a high probability of the continuous hidden node collisions (CHNCs), which seriously decreases network throughput. Based on this observation, we propose a cost‐efficient recovery mechanism to achieve fast self‐healing when LR‐WPANs suffer CHNCs, while introducing no overhead when there are no collisions. Simulation results demonstrate the efficiency of our proposed protocol in terms of network throughput and power saving. Copyright © 2011 John Wiley & Sons, Ltd.     

CRDA: a collision resolution and dynamic allocation MAC protocol tointegrate data and voice in wireless networks

One key requirement for radio access in advanced, third generation (3G) mobile communication systems is the ability to accommodate a variety of services via a flexible and efficient medium access control (MAC) protocol. The paper presents and evaluates a new multiple access protocol termed CRDA (collision resolution and dynamic allocation), which has the potential to meet the above requirement. CRDA is basically a slotted packet-reservation multiple access technique with dedicated reservation slots, which allows the main shortcoming of previous PRMA schemes, i.e., contention, to be overcome through the integration in the MAC protocol of a code-division multiple-access (CDMA) transmission mode used to access the reservation slots. This prevents collisions during the reservation phase and enhances channel throughput, notably in the case of mixed voice/data traffic. Our simulations of the CRDA MAC integrate voice channels with data sources, generating what we call advanced data traffic, which has a very similar shape to the actual traffic generated by World Wide Web (WWW) applications. The standard assumption of Poissonian data traffic is also considered. Our conclusion is that the CRDA MAC protocol satisfactorily accommodates both types of traffic     

A multiple relay‐based medium access control protocol in multirate wireless ad hoc networks with multiple beam antennas

The advanced technique of multiple beam antennas is recently considered in wireless networks to improve the system throughput by increasing spatial reuse, reducing collisions, and avoiding co‐channel interference. The usage of multiple beam antennas is similar to the concept of Space Division Multiple Access (SDMA), while each beam can be treated as a data channel. Wireless networks can increase the total throughput and decrease the transmission latency if the physical layer of a mobile node can support multirate capability. Multirate wireless networks incurs the anomaly problem, because low data rate hosts may influence the original performance of high data rate hosts. In this work, each node fits out multiple beam antennas with multirate capability, and a node can either simultaneously transmit or receive multiple data on multiple beams. Observe that the transmitting or receiving operation does not happen at the same time. In this paper, we propose a multiple relay‐based medium access control (MAC) protocol to improve the throughput for low data rate hosts. Our MAC protocol exploits multiple relay nodes and helps the source and the destination to create more than one data channel to significantly reduce the transmission latency. Observe that low data rate links with long‐distance transmission latencies are distributed by multiple relay nodes, hence the anomaly problem can be significantly alleviated. In addition, the ACK synchronization problem is solved to avoid the condition that source nodes do not receive ACKs from destination nodes. An adjustment operation is presented to reduce unnecessary relay nodes during the fragment burst period. Finally, simulation results illustrate that our multiple relay‐based MAC protocol can achieve high throughput and low transmission latency. Copyright © 2009 John Wiley & Sons, Ltd.     

A schedule‐based medium access control protocol for mobile wireless sensor networks

Recent advances in body area network technologies such as radio frequency identification and ham radio, to name a few, have introduced a huge gap between the use of current wireless sensor network technologies and specific needs of some important wireless sensor network applications such as medical care, disaster relief, or emergency preparedness and response. In these types of applications, the mobility of nodes can occur, leading to the challenge of mobility handling. In this paper, we address this challenge by prioritizing transmissions of mobile nodes over static nodes. This is achieved by using shorter contention windows in reservation slots for mobile nodes (the so‐called backoff technique) combined with a novel hybrid medium access control (MAC) protocol (the so‐called versatile MAC). The proposed protocol advocates channel reuse for bandwidth efficiency and management purpose. Through extensive simulations, our protocol is compared with other MAC alternatives such as time division multiple access and IEEE 802.11 with request to send/clear to send exchange, chosen as benchmarks. The performance metrics used are bandwidth utilization, fairness of medium access, and energy consumption. The superiority of versatile MAC against the studied benchmark protocols is established with respect to these metrics. Copyright © 2012 John Wiley & Sons, Ltd.     

Design of MAC protocols with fast collision resolution for wireless local area networks

Development of efficient medium access control (MAC) protocols providing both high throughput performance for data traffic and good quality of service (QoS) support for real-time traffic is the current major focus in distributed contention-based MAC protocol research. In this paper, we propose an efficient contention resolution algorithm for wireless local area networks, namely, the fast collision resolution (FCR) algorithm. The MAC protocol with this new algorithm attempts to provide significantly higher throughput performance for data services than the IEEE 802.11 MAC algorithm and more advanced dynamic tuning backoff (DTB) algorithm. We demonstrate that this algorithm indeed resolves collisions faster and reduces the idle slots more effectively. To provide good fairness performance and to support good QoS for real-time traffic, we incorporate the self-clocked fair queueing algorithm and a priority scheme into the FCR algorithm and come up with the real-time FCR (RT-FCR) algorithm, and show that RT-FCR can simultaneously achieve high throughput and good fairness performance for nonreal-time traffic while maintaining satisfactory QoS support for real-time traffic.     

A bit-map-assisted dynamic queue protocol for multiaccess wireless networks with multiple packet reception

A novel network-assisted (signal processing based) medium access control (MAC) protocol known as the bit-map-assisted dynamic queue (BMDQ) is presented. The protocol is explicitly designed for a wireless slotted system with multiple packet reception (MPR) capability. In the proposed protocol, the traffic in the channel is viewed as a flow of transmission periods (TPs). Each TP has a bit-map (BM) slot at the beginning followed by a data transmission period (DP). The BM slot is reserved for user detection so that accurate knowledge of the active user set (AUS) can be obtained. Then, given the knowledge of the AUS and the channel MPR matrix, the number of users that can access the channel simultaneously in each packet slot in the DP is chosen to maximize the conditional throughput of every packet slot. Compared with other conventional and network-assisted MAC protocols, the proposed BMDQ protocol yields better performance. Its maximum steady-state throughput is close to the channel MPR capacity, and it can achieve the same throughput with lower traffic load and smaller delay. Performance issues are investigated analytically and via simulations.     

Multiple access protocol for power-controlled wireless access nets

We consider ad hoc wireless networks that are configured as Mobile Backbone Networks. A hierarchical network architecture is synthesized, consisting of Access Nets (ANets) and Backbone Nets (BNets). Each ANet is managed by a (dynamically elected) Backbone Node (BN) that is equipped with higher capability (transmission and processing) modules. The BNs are chosen from currently active mobile backbone-capable nodes or are represented by (ground and/or airborne) unmanned vehicles (UVs) that are guided into selected positions. We develop and investigate a new joint power controlled medium access control (MAC) algorithm for wireless access nets (ANets). Under our new protocol, the net backbone node instructs the ANet nodes to make power control adjustments while simultaneously allocating to them slots for the requested transmissions of their packets. This algorithm, in contrast to other employed conventional graph-based scheduling algorithms, satisfies the requirement that a minimum signal-to-interference and noise ratio (SINR) is met at all intended receivers. We show our algorithm to lead to a significant increase in the net throughput level by attaining high spatial reuse.     

AIRMAIL: A link-layer protocol for wireless networks

This paper describes the design and performance of a link-layer protocol for indoor and outdoor wireless networks. The protocol is asymmetric to reduce the processing load at the mobile, reliability is established by a combination of automatic repeat request and forward error correction, and link-layer packets are transferred appropriately during handoffs. The protocol is namedAIRMAIL (AsymmetrIc Reliable Mobile Access In Link-layer). The asymmetry is needed in the design because the mobile terminals have limited power and smaller processing capability than the base stations. The key ideas in the asymmetric protocol design consist of placing bulk of the intelligence in the base station as opposed to placing it symmetrically, in requiring the mobile terminal to combine several acknowledgments into a single acknowledgment to conserve power, and in designing the base stations to send periodic status messages, while making the acknowledgment from the mobile terminal eventdriven. The asymmetry in the protocol design results in a one-third reduction of compiled code. The forward error correction technique incorporates three levels of channel coding which interact adaptively. The motivation for using a combination of forward error correction and link-layer retransmissions is to obtain better performance in terms of end-to-end throughput and latency by correcting errors in an unreliable wireless channel in addition to end-to-end correction rather than by correcting errors only by end-to-end retransmissions. The coding overhead is changed adaptively so that bandwidth expansion due to forward error correction is minimized. Integrity of the link during handoffs (in the face of mobility) is handled by window management and state transfer. The protocol has been implemented. Experimental performance results based on the implementation are presented.     

A signaling architecture for wireless ATM access networks

A multiservice wireless Asynchronous Transfer Mode (ATM) access system is considered from a signaling protocol viewpoint. In an attempt to generalize and extend results and experiences obtained from the specification, design, and implementation of fixed ATM‐based access networks, we extend the concept of the broadband V interface (referred to as VB) for application to wireless ATM access networks. The proposed architecture follows the signaling structure of Broadband ISDN (B‐ISDN) User–Network Interface (UNI), thus offering the possibility for integration of the wireless ATM access system into fixed B‐ISDN. It is shown that the use of the proposed access signaling architecture provides cost effective implementations without degrading the agreed Quality of Service (QoS), and simplifies call/connection and handover control. The evaluation of the proposed access signaling protocol structure yields results that fall within acceptable ATM signaling performance measures. A performance comparison of our approach with an alternative access signaling configuration is also carried out to quantify the relative gains. This revised version was published online in August 2006 with corrections to the Cover Date.