1-persistent DUAL channel local area network for integrated voice and data application

It is a well-known fact that the carrier sense multiple access with collission detection (CSMA/CD) protocol would suffer from throughput degradations and long packet delays at heavy loads due to excessive collisions and retransmissions, and thus is not suitable for voice/data integration. Recently, a new protocol called carrier sense multiple access with time-split collision detection and split channel reservation (CSMA-TCD-SCR) has been proposed¹ to improve the channel throughput of CSMA/CD protocol by splitting the common channel into dual channels, i.e. one for data transfer and the other for reservation. It has been shown that the CSMA-TCD-SCR protocol improves the channel throughput and stability performance significantly.¹ In this paper, we propose a 1-persistent dual-channel LAN (1P-DC-LAN) protocol with the tree algorithm for reservation, which is an extension of the CSMA-TCD-SCR protocol, for voice/data integration applications. Through approximate analytical modelling and computer simulations, it has been demonstrated that the 1P-DC-LAN protocol exhibits nearperfect scheduling throughputs for data transmission and highly bounded voice packet delays. In addition, the results were compared with IEEE 802.3 CSMA/CD and twin-channel CSMA/CD.     

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 modified medium access control algorithm for systems with iterative decoding

Efficient transmission methods for fading radio channels often require an iterative decoder. This is for example the case for systems using turbo codes. Receiver decoder iterations could potentially lead to a latency problem which impacts the performance of the medium access control protocol. In this paper, we present modifications based on the carrier sense multiple access with collision avoidance (CSMA/CA) medium access control (MAC) protocol to accommodate the increased latency in the iterative processing. One area of applications is wireless local area networks (WLANs) with high data rate. The simulation results performed in the IEEE 802.11a WLAN environment by replacing the 802:11a's convolutional coding with turbo coding demonstrate that the proposed algorithm provides a throughput gain over the conventional method.     

CSMA with reservations by interruptions (CSMA/RI): a novel approachto reduce collisions in CSMA/CD

This paper proposes an enhancement for the carrier sense multiple access with collision detection (CSMA/CD) protocol, called CSMA with reservations by interruptions (CSMA/RI). This new protocol uses a novel approach to reserve capacity by interrupting an ongoing packet transmission. The performance of the protocol is studied by simulations under realistic (long range dependent) traffic conditions and compared to the CSMA/CD, token ring protocols, as well as with the work conserving G/D/1 queue. It is demonstrated that CSMA/RI always offers better performance than CSMA/CD, and under certain realistic assumptions regarding packet size, the performance of CSMA/RI can be very close to that of token-ring and G/D/1     

On detecting termination in cognitive radio networks

The cognitive radio networks are an emerging wireless communication and computing paradigm. The cognitive radio nodes execute computations on multiple heterogeneous channels in the absence of licensed users (a.k.a. primary users) of those bands. The termination detection is a fundamental and non‐trivial problem in distributed systems. In this paper, we propose a termination detection protocol for multi‐hop cognitive radio networks where the cognitive radio nodes are allowed to tune to channels that are not currently occupied by primary users and to move to different locations during the protocol execution. The proposed protocol applies a credit‐distribution‐and‐aggregation approach and maintains a new kind of logical structure, called the virtual tree‐like structure. The virtual tree‐like structure helps in decreasing the latency involved in announcing termination. Unlike conventional tree structures, the virtual tree‐like structure does not require a specific node to act as the root node that has to stay involved in the computation until termination announcement; hence, the root node may become idle soon after finishing its computation. Also, the protocol is able to detect the presence of licensed users and announce strong or weak termination, whichever is possible. Copyright © 2014 John Wiley & Sons, Ltd.     

Channel estimation and compensation for preamble-assisted DAPSKtransmission in digital mobile radio system

This paper presents a novel channel estimation and compensation technique, combining fading estimation and frequency offset estimation, for preamble-assisted differentially encoded amplitude- and phase-shift keying (DAPSK) transmission in a digital mobile radio system. The received preamble symbols are used to estimate the combined distortions caused by multipath fading and frequency offset. The detected data symbols as well as preamble symbols are used to enhance the accuracy of the estimation process. The combined distortions can be compensated in the data symbols at the same time. The storage-delay time of the estimation process is only several symbols long. A series of computer simulations have been carried out to investigate the bit error rate performance of the preamble-assisted 16-DAPSK signals with uncertain frequency offset in the frequency-nonselective and frequency-selective Rayleigh fading channels     

Analysis of power ramping schemes for UTRA-FDD random access channel

The random access channel (RACH) in a universal terrestrial radio access-frequency division duplex (UTRA-FDD) system is a contention-based channel mainly used to carry control information from mobile stations (MS) to base stations (BS). The transmission of a random access request contains two steps: preamble transmission and message transmission. In preamble transmission, the power ramping technique is used to favor the delayed preambles by stepping up the transmission power after each unsuccessful access. In doing so, the success of transmitting a long-delayed preamble is increased due to the power capture effect. This paper analyzes the blocking, throughput, and delay performance of preamble transmission under three power ramping schemes with fixed, linear, and geometric step sizes. The interference caused by different power ramping schemes is also compared.     

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     

Voice and Data on a CATV Network

A technique for transmitting voice and data on a conventional subsplit CATV network is described. The technique uses a variation on the carrier sense multiple access/collision detection protocol used in local area networks. A variation on this protocol, called movable slot TDM allows periodic voice Sources to share this network without distorting the voice signal. A scheme for sharing frequency spectrum and space is outlined that removes the distance and transmission rate constraints associated with such networks. A transmission strategy is described which allows these protocols to be used on a subsplit CATV system. The system is thus a candidate for local/metropolitan area networks Which support digital voice and data services along with analog (mostly one-way) video.     

Protocol design for mobile radio group communications oversatellite

A protocol design for a mobile radio service supporting half-duplex push-to-talk voice communications over mobile satellite systems is presented. The service enables a closed group of mobile radio users to communicate among themselves, so that a transmission from any user is received by all. A key issue is the efficient utilization of satellite channels. Demand-assignment multiple access (DAMA) is employed to allocate channels only to those user groups in active sessions of conversations. Owing to the unique characteristics of the half-duplex point-to-multipoint group communications, a new DAMA protocol is proposed for this service. Within a channel assigned to a user group, access contentions exacerbated by very long round-trip delay can occur. A signaling protocol is devised to arbitrate access contentions so as to improve the utilization of the assigned channel. The proposed access control protocol offers 65% or 18% improvement in throughput capacity compared to manual carrier-sensed access without and with collision detection, respectively     

Announced Retransmission Random Access Protocols

A new contention-based broadcast multiaccess protocol called announced retransmission random access (ARRA) is introduced and analyzed in this paper. The proposed class of protocols increases the capacity of a slotted random access channel by adding a small amount of potentially useful control information to every message transmission. In particular, the ARRA technique requires users to announce the intended location of their potential retransmission slot (to be used in the event of a collision) over a low-rate announcement subchannel, so that conflicts between new and retransmitted messages can be prevented. The proposed protocols provide significant capacity improvements over conventional contention protocols, without sacrificing the simplicity and operational convenience associated with random access. It is shown that with a modest amount of processing and storage at the terminals, capacities in the range of 0.5-0.6 can be achieved, as compared with 0.37 for slotted ALOHA and 0.4-0.5 for the more efficient tree algorithm-based collision resolution algorithms (CRA's). Specifically, the basic ARRA protocol, in which announced retransmissions take place unconditionally, has a capacity of about 0.53. An improved algorithm (called extended ARRA), which involves aborting predictably unsuccessful retransmissions, has a capacity of 0.6. In addition, because of delay considerations, the proposed ARRA protocols are well suited for operation on satellite channels.     

一种并行传输的水声Ad hoc网络多址接入(PTMA)协议

由于存在"隐藏终端"和"暴露终端"的问题,无线Ad hoc网络的应用受到极大的限制.进一步,由于水声信道的特点,例如有用的频率带宽很窄,强时变、多途和长传播时延,使得设计水声Ad hoc网络具有自身特点和难度.本文中,我们为此提出了一种新的多址接入控制(MAC)协议,即并行传输多址接入(PTMA)协议.该协议基于如下思想:为消除冲突而进行多信道预约,这样能在多个信道上并行地传输数据;为缩短等待clear_-to_-send(CTS)的时间,当request_-to_-send(RTS)刚发送完就立即发送分组数据,而不必收到CTS后再发.通过使用OPNET Modeler/Radio仿真器得到的仿真结果显示:PTMA协议能取得较之于适合无线Ad hoc网络的多址接入协议更高的吞吐性能和较低的端到端传播时延.     

Analysis of a dynamic reservation protocol for interactive dataservices on TDMA-based wireless networks

This paper presents the dynamic reservation protocol for supporting variable-rate data services on time-division multiple-access based wireless networks. It allows a large number of data terminals to access data applications by sharing a reserved data-carrier. Through dynamic reservation data terminals can get their needed radio channels for uplink transmission without contention. The protocol performance is evaluated by queuing analysis and verified by computer simulation     

Interference‐resilient spectrum sharing with collision detection and data recovery for cognitive radio networks

Data recovery under collision of primary/secondary users in cognitive radio networks is largely an unaddressed problem. Existing approaches require either (a) retransmissions, (b) interference‐free alignment of transmission parameters, or (c) prior knowledge for data recovery. In contrast to the existing approaches, the paper proposes estimation of channel state information based on received collided frames and recommends techniques for spectrum sharing, collision detection, and data recovery. Specifically, based on estimated channel vector, interference‐resilient spectrum‐sharing protocol and techniques are proposed for (a) identification of primary user (PU) activity before (or during) secondary user's (SU's) transmission, (b) MIMO channel estimation under collision, (c) optimal pilot permutation, and (d) interference cancellation (with/without receiver diversity). Results are reported for different baseband modulation techniques under frequency selective/flat fading channel scenarios that demonstrate the efficacy of a proposed work.     

I-MAC: an incorporation MAC for wireless sensor networks

This paper proposes an innovative MAC protocol called I-MAC. Protocol for wireless sensor networks, which combines the advantages of collision tolerance and collision cancellation. The protocol increases the number of antenna in wireless sensor nodes. The purpose is to monitor the occurrence of packet collisions by increasing the number of antenna in real time. The built-in identity structure is used in the frame structure in order to help the sending node to identify the location of the receiving node after a data packet collision is detected. Packets can be recovered from where the conflict occurred. In this way, we can monitor the conflict for a fixed period of time. It can improve the channel utilisation through changing the transmission probability of collision nodes and solve the problem of hidden terminal through collision feedback mechanism. We have evaluated our protocol. Our results show that the throughput of I-MAC is 5 percentage points higher than that of carrier sense multiple access/collision notification. The network utilisation of I-MAC is more than 92%.     

Frame and carrier frequency synchronization algorithm for wireless body area network

A wireless body area network (WBAN) is a radio‐frequency‐based wireless communication technology that consists of a number of different sensor and actuator nodes interconnected with a body gateway. Considering the constrained resources in WBAN devices, simple and noise‐robust synchronization algorithms are required. Frame synchronization and frequency offset estimation are extremely important in the design of a robust WBAN receiver. In this paper, a detection strategy such as frame synchronization and frequency estimation is described in the WBAN system, which can improve the receiver performance. In doing so, algorithms are designed or chosen for the frame detection, carrier frequency offset synchronization, and joint fine‐time and phase‐offset estimation by exploiting the spike‐like property of the physical layer convergence protocol preamble and the frame structure in the WBAN system. The performance of the WBAN synchronization receiver is verified by computer simulation. Copyright © 2015 John Wiley & Sons, Ltd.     

Chip-level differential encoding/detection of spread-spectrumsignals for CDMA radio transmission over fading channels

This paper is concerned with the design and performance evaluation of a direct-sequence spread-spectrum transmission and signal-detection technique for application to code-division multiple-access mobile radio networks. Unlike the conventional differential encoding/detection of data symbols, such a technique envisages differential encoding/detection of the spreading code chips to counteract the fast time-selective fading encountered in mobile radio transmissions. Binary PSK modulation on a Rician frequency-flat-fading channel is assumed, with Gaussian and Rayleigh channels as particular cases. The bit-error rate performance of the receiver is analytically evaluated as a function of the relevant system parameters, and the impact on the receiver performance of a carrier frequency offset is also investigated     

Performance analysis of the IEEE 802.11 distributed coordinationfunction

The IEEE has standardized the 802.11 protocol for wireless local area networks. The primary medium access control (MAC) technique of 802.11 is called the distributed coordination function (DCF). The DCF is a carrier sense multiple access with collision avoidance (CSMA/CA) scheme with binary slotted exponential backoff. This paper provides a simple, but nevertheless extremely accurate, analytical model to compute the 802.11 DCF throughput, in the assumption of finite number of terminals and ideal channel conditions. The proposed analysis applies to both the packet transmission schemes employed by DCF, namely, the basic access and the RTS/CTS access mechanisms. In addition, it also applies to a combination of the two schemes, in which packets longer than a given threshold are transmitted according to the RTS/CTS mechanism. By means of the proposed model, we provide an extensive throughput performance evaluation of both access mechanisms of the 802.11 protocol     

移动Ad HOc网络中的公平按需多址接入协议

基于快速、有效竞争预约接入、无冲突轮询传输的思想和带冲突预防的冲突分解策略,本文提出了适于移动Ad Hoc网络的公平按需多址接入(FODA)协议.该协议在分群结构的基础上,利用公平冲突预防算法预约信道资源获得轮询服务,从而完全消除了载波侦听方式下多跳无线网络业务传输中的隐藏终端和暴露终端问题.另外,公平冲突预防算法解决了节点竞争接入时的冲突问题和不公平现象.最后,仿真结果表明,与带冲突避免的载波侦听多址接入(CSMA/CA)和轮询协议相比,FODA协议可以提供较高的信道吞吐量、较低的平均消息丢弃率和平均消息时延.