A multi-layer collision resolution multiple access protocol for wireless networks

In mobile communication networks operating in unreliable physical transmission, random access protocol with the collision resolution (CR) scheme is more attractive than the ALOHA family including carrier sense multiple access (CSMA) [IEEE Networks (September 1994) 50–64], due to likely failure on the channel sensing. Being a member of CR family schemes, a protocol known as non-preemptive priority multiple access (NPMA) is utilized in a new high-speed wireless local area network, HIPERLAN, standardized by European Telecommunication Standard Institute (ETSI). A conceptually three-layer CR multiple access protocol generalized from NPMA, supporting single type of traffic, is thus presented and analyzed in this paper. The CR capability of such a protocol (and hence NPMA) is proved to be significant by numerical substantiation that additional collision detection schemes are dispensable; also its throughput/delay performance is excellent when the proportion of the transmission phase to a channel access cycle is large enough (i.e., the winner of contention should transmit all of its packets successively). On the other hand, the simulated performance of NPMA serving integrated traffic is not fully satisfactory, primarily due to its distributed control mode and distinguishing traffic types only by the prioritization process.     

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.     

Hierarchy schedule sensing protocol for CDMA wireless networks performance study under multipath, multiuser interference, and collision-capture effect

This paper studies a multiple access control protocol, hierarchy schedule sensing protocol, for CDMA wireless data centric networks characterized by high terminal density in a small area. In particular, this paper focuses on the impact of packet collision with capture effect on performance of a network based on the protocol, where a common-coded permission frame beacon is used to schedule-transmission requests to avoid collisions. To further reduce scheduling delay, hierarchical group-based coding is introduced to the scheme. The performance of such a network is analyzed considering packet collisions, capture effect, multipath-interference (Ml), and multiuser interference (MUI) with the help of a Markovian chain model. The average packet collision-rate with and without capture effect is explicitly derived, the performance of the protocol is compared with traditional receiver-based code protocol to show that, despite its low complexity, it is a fairly robust multiple access control protocol featured by uniformly high throughput and low delay.     

一种基于捕获的扩频分组无线网MAC层协议及其性能分析

在分组接入过程中,当每个用户终端以随机竞争的方式获得所需的频谱资源时,会引起用户间的冲突和资源的浪费,造成系统性能的降低。本文引入了一种基于捕获的接入方法,当一个时隙中存在多个干扰分组时,该方法仍有捕获到某个分组的可能,该方法在系统高负载的情况下能有效地利用资源。性能分析和计算结果表明,基于捕获的方法改善了系统的性能。     

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.     

An efficient packet sensing MAC protocol for wireless networks

The Group Allocation Multiple Access with Packet-Sensing (GAMA-PS) protocol for scheduling real-time and datagram traffic in a wireless LAN is specified and analyzed. By maintaining a dynamically-sized cycle that changes in length depending on the amount of network traffic, GAMA-PS is able to efficiently control channel access while ensuring that there are no collisions of data packets. Each cycle contains a contention period and a group-transmission period; a station with data to send competes for membership in the “transmission group” by using packet sensing to successfully complete an RTS/CTS message exchange during the contention period. Once a station is a member of the transmission group, it is able to transmit a collision-free data packet during each cycle; as long as a station has data to send, it maintains its position in the group. This revised version was published online in June 2006 with corrections to the Cover Date.     

Multiuser diversity with capture for wireless networks: protocol and performance analysis

In a wireless network, with the aid of rate adaptation, multiuser diversity can be exploited by allowing the mobile user with the best channel to use the channel. However, the overhead that results from polling mobile stations to obtain channel state information (CSI) in large networks can outweigh the multiuser diversity gain. In this paper, we propose a wireless medium access control protocol, namely multiuser diversity with capture (MDC), which explicitly employs the capture effect to obviate the overhead problem. We analyze the good put performance of MDC and compare it with the medium access diversity (MAD) scheme proposed in the literature. Our results show that MDC is effective in networks with radio receivers possessing reasonably good capture properties and in networks where the number of mobile stations is reasonably large.     

Cross-layer radio resource allocation in packet CDMA wireless mobile networks

An efficient radio resource allocation scheme is crucial for guaranteeing the quality of service (QoS) requirements and fully utilizing the scarce radio resources in wireless mobile networks. Most of previous studies of radio resource allocation in traditional wireless networks concentrates on network layer connection blocking probability QoS. In this paper, we show that physical layer techniques and QoS have significant impacts on network layer QoS. We use a concept of cross-layer effective bandwidth to measure the unified radio resource usage taking into account both physical layer linear minimum-mean square error (LMMSE) receivers and varying statistical characteristics of the packet traffic in code devision multiple access (CDMA) networks. We demonstrate the similarity between traditional circuit-switched networks and packet CDMA networks, which enables rich theories developed in traditional wireless mobile networks to be used in packet CDMA networks. Moreover, since both physical layer signal-to-interference ratio (SIR) QoS and network layer connection blocking probability QoS are considered simultaneously, we can explore the tradeoff between physical layer QoS and network layer QoS in packet CDMA networks. This work is supported by Natural Science and Engineering Research Council of Canada. Please address all correspondence to Professor Vikram Krishnamurthy at the above address. Fei Yu received the Ph.D. degree in electrical engineering from the University of British Columbia in 2003. From 2002 to 2004, he was with Ericsson (in Lund, Sweden), where he worked on the research and development of dual mode UMTS/GPRS handsets. From 2005, he has been working in Silicon Valley at a start-up, where he conducts research and development in the areas of advanced wireless communication technologies and new standards. After completing the PhD, he has been a research associate in the Department of Electrical and Computer Engineering at the University of British Columbia. His research interests include cross-layer optimization, QoS provisioning and security in wireless networks. Vikram Krishnamurthy (S’90-M’91-SM’99-F’05) was born in 1966. He received his bachelor’s degree from the University of Auckland, New Zealand in 1988, and Ph.D. from the Australian National University, Canberra, in 1992. Since 2002, he has been a professor and Canada Research Chair at the Department of Electrical Engineering, University of British Columbia, Vancouver, Canada. Prior to this he was a chaired professor at the Department of Electrical and Electronic Engineering, University of Melbourne, Australia. His research interests span several areas including ion channels and nanobiology, stochastic scheduling and control, statistical signal processing and wireless telecommunications. Dr. Krishnamurthy has served as associate editor for IEEE Transactions on Signal Processing, IEEE Transactions Aerospace and Electronic Systems, IEEE Transactions Nanobioscience, IEEE Transactions Circuits and Systems II, Systems and Control Letters and European Journal of Applied Signal Processing. He was guest editor of a special issue of IEEE Transactions on NanoBioScience, March 2005 on bio-nanotubes.     

A novel random wireless packet multiple access method using CDMA

Random packet CDMA, a novel packet-based multiple access scheme for connectionless, uncoordinated random channel access is proposed. Random packet CDMA, or RP-CDMA, utilizes a novel packet format which consists of a short header and a data portion. Each header is spread with a unique spreading code which is identical for all users and packets, while the data portion of each packet is spread by a randomly chosen spreading sequence. The receiver operates in two stages: header detection and data detection. For header detection a conventional spread spectrum receiver is sufficient. Headers are spread with a large enough processing gain to allow detection even in severe interference. The data portion is decoded with a sophisticated receiver, such as a multiuser detector, which allows for successful decoding of overlapping active packets. It is shown that the RP-CDMA system is detector capability limited and that it can significantly outperform spread ALOHA systems whose performance is limited by the channel collision mechanism. RP-CDMA also experiences a much smaller packet retransmission rate than conventional or spread ALOHA, and provides better spectral efficiencies.     

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.     

Distributed collision control with the integration of packet size for congestion control in wireless sensor networks

Several great features offered by wireless sensor networks (WSN) result in its wide deployment in various remote and continuous monitoring applications. As such, managing huge collected readings in this domain posted many challenges due to its design limitations. In order to provide seamless data transmission, which is of utmost importance in those delay‐sensitive applications, minimum delay and packet loss occurrence should be considered. Specifically, this paper addresses the common issue of congested networks in WSN with the combination technique of variance‐based distributed contention control (DCC‐V) and packet size optimization. The proposed integration technique, which operates on medium access control layer, takes into consideration the packet size advantages as it plays a key role in determining successful data delivery, given the error‐prone nature of WSN. While ensuring fewer corrupted packets, the proposed contention window (CW) in DCC‐V minimizes the chances of packet collisions and so alleviates congestion. In this technique, CW is determined based on slot utilization and average collision values, which also involve standard deviation measurements. Simulation analysis using network simulator‐2 shows outstanding performance of the proposed solution compared with the existing IEEE 802.15.4 protocol. Copyright © 2014 John Wiley & Sons, Ltd.     

A CDMA wireless packet network for voice-data transmissions

This letter investigates the possibility of integrating voice and data communications in a CDMA wireless packet network to provide access to a base station over a common short-range radio uplink channel for many spatially dispersed voice and data user terminals. Speech activity detection is assumed for voice communications to temporarily devote codes unused by voice user terminals during silence periods to data transmissions. The network proposed exhibits a good performance both in terms of quality of voice communications which is independent of data transmissions and maximum data traffic load supported with bounded delay     

QoS-oriented packet scheduling for wireless multimedia CDMA communications

In the third-generation (and beyond) wireless communication systems, there will be a mixture of different traffic classes, each having its own transmission rate characteristics and quality-of-service (QoS) requirements. In this paper, a QoS-oriented medium access control (MAC) protocol with fair packet loss sharing (FPLS) scheduling is proposed for wireless code-division multiple access (CDMA) communications. The QoS parameters under consideration are the transmission bit error rate (BER), packet loss, and delay requirements. The MAC protocol exploits both time-division and code-division statistical multiplexing. The BER requirements are guaranteed by properly arranging simultaneous packet transmissions and controlling there transmit power levels, whereas the packet loss and delay requirements are guaranteed by proper packet scheduling. The basic idea of FPLS is to schedule the transmission of multimedia packets in such a way that all the users have a fair share of packet loss according to their QoS requirements, which maximizes the number of the served users under the QoS constraints. Simulation results demonstrate effectiveness of the FPLS scheduler, in comparison with other previously proposed scheduling algorithms.     

Distributed code assignments for CDMA packet radio networks

Code-division multi-access (CDMA) techniques allow many users to transmit simultaneously in the same band without substantial interference by using approximately orthogonal (low cross-correlation) spread-spectrum waveforms. Two-phase algorithms have been devised to assign and reassign spread-spectrum codes to transmitters, to receivers and to pairs of stations in a large dynamic packet radio network in polynomial times. The purpose of the code assignments is to spatially reuse spreading codes to reduce the possibility of packet collisions and to react dynamically to topological changes. These two-phase algorithms minimize the time complexity in the first phase and minimize the number of control packets needed to be exchanged in the second phase. Therefore, they can start the network operation in a short time, then switch to the second phase with the goal of adapting to topological changes. A pairwise code-assignment scheme is proposed to assign codes to edges. Simulations based on well-controlled topologies (sparse topologies) show that the scheme requires much fewer codes than transmitter-based code assignment, while maintaining similar throughput performance     

QOS distributed routing protocol for mobile ad-hoc wireless networks using intelligent packet carrying systems

The wireless network should provide high throughput and positive status and this paper suggest a system that supports real-time communications with excellence of service necessities for application based on wireless communications. In addition a hybrid network that interconnects both mobile networks and wireless networks. By inheriting the features of Solid Rocket Booster technology for mobile and wireless networks the race condition, and invalid condition problem has been solved. The number of packets received may vary based on the parameter like mobility, energy, memory, bandwidth, jamming and other parameter. In past years many algorithm has been proposed for increasing the probability of packet delivery but it’s still a challenge. This paper uses an algorithm called intelligent packet carrying systems; it provides a tracking mechanism that tracks nodes in rural places. The effectives and reability has been calculated and the results are obtained using OPNET simulator.     

An FDD wideband CDMA MAC protocol with minimum-power allocation and GPS-scheduling for wireless wide area multimedia networks

A frequency division duplex (FDD) wideband code division multiple access (CDMA) medium access control (MAC) protocol is developed for wireless wide area multimedia networks. In order to reach the maximum system capacity and guarantee the heterogeneous bit error rates (BERs) of multimedia traffic, a minimum-power allocation algorithm is first derived, where both multicode (MC) and orthogonal variable spreading factor (OVSF) transmissions are assumed. Based on the minimum-power allocation algorithm, a multimedia wideband CDMA generalized processor sharing (GPS) scheduling scheme is proposed. It provides fair queueing to multimedia traffic with different QoS constraints. It also takes into account the limited number of code channels for each user and the variable system capacity due to interference experienced by users in a CDMA network. To control the admission of real-time connections, a connection admission control (CAC) scheme is proposed, in which the effective bandwidth admission region is derived based on the minimum-power allocation algorithm. With the proposed resource management algorithms, the MAC protocol significantly increases system throughput, guarantees BER, and improves QoS metrics of multimedia traffic.     

Performance evaluation of a modified PRMA protocol for joint voiceand data packet wireless networks

In this paper, a modified version of the packet reservation multiple-access (PRMA) protocol is proposed to provide spatially dispersed voice and data user terminals wireless access to a base station over a common short-range radio channel. An analytical approach is presented in order to derive system performance in terms of mean data message delay and voice packet dropping probability. A suitable permission probability design is also proposed to enhance system performance. Performance comparisons with an extension of the PRMA protocol to voice data systems previously reported in literature are shown to highlight the better behavior of this approach     

A slotted CDMA protocol with BER scheduling for wireless multimedianetworks

In future wireless multimedia networks, there will be a mixture of different traffic classes which have their own maximum tolerable bit error rate (BER) requirements. In this paper, a novel medium access control (MAC) protocol called wireless multimedia access control protocol with BER scheduling (in short form, WISPER) for CDMA-based systems is proposed. WISPER utilizes the novel idea of scheduling the transmission of multimedia packets according to their BER requirements. The scheduler assigns priorities to the packets, and performs an iterative procedure to determine a good accommodation of the highest-priority packets in the slots of a frame so that packets with equal or similar BER requirements are transmitted in the same slots. The proposed WISPER protocol has been validated using a software emulator on the cellular environment. Performance evaluation results based on the implementation are also included     

Split-channel pipelined packet scheduling for wireless networks

To reduce medium access control (MAC) overhead and improve channel utilization, there has been extensive research on dynamically adjusting the channel access behavior of a contending station based on channel feedback information. This paper explores an alternative approach, named pipelined packet scheduling, to reduce the MAC overhead. MAC overheads can be divided into bandwidth-dependent and bandwidth-independent components and these overheads can both be reduced by using split-channel pipelining mechanisms, as demonstrated in this paper. In the past, pipelining mechanisms have not been well studied. This paper introduces two total pipelining schemes that attempt to fully pipeline contention resolution with data transmission. Further, the paper identifies shortcomings of total pipelining in the wireless environment and proposes a partial pipelining approach to overcome these shortcomings. Simulation results show that substantial performance improvement in channel utilization, average packet access delay, and access energy cost can be achieved with a properly designed scheme.     

基于蚂蚁算法的CDMA多媒体数据规划协议

本文讨论了MC-CDMA多媒体数据规划协议,多媒体数据按BER指标分类,根据各类数据BER要求,采用蚂蚁算法对用户分组数据进行规划.对照传统的"先到先服务"(FCFS)方法,进行了仿真分析,结果表明平均吞吐率、平均时延及平均丢包率均有改善.