Minislotted packet reservation multiple access

A minislotted packet reservation multiple access (PRMA) protocol is proposed in response to the disadvantage of PRMA wherein an entire slot is wasted in the event of a collision. The proposed protocol is shown to yield improvements over PRMA at the expense of introducing small amounts of additional clipping in some talkspurts.<>     

On the performance of packet reservation multiple access with fixedand dynamic channel allocation

The evaluation of packet reservation multiple access (PRMA) is extended from a single cell case, investigated in several previous papers, to a cellular environment characterized by user mobility and by the interference from other cells. The analysis is based on a comparison of PRMA performances with those of classical circuit switching schemes. The comparison methodology is defined, and the comparison, performed by means of a simulation program based on a dynamic traffic model, is discussed     

A packet reservation multiple access assisted cordlesstelecommunication scheme

A packet reservation multiple access (PRMA) assisted microcellular cordless telecommunications (CT) system is investigated for office type environments in absence of cochannel interference. The objective speech quality is found as a function of channel signal-to-noise ratio (SNR) for transmissions over narrowband Rayleigh fading channels, parameterized with the number of PRA users. A moderate complexity 16-ary CT scheme constituted by a 4-bit/symbol 32-kbps adaptive differential pulse code modulation (ADPCM) speech codec, Reed-Solomon forward error correction (FEC) codec, and diversity-assisted 16-level star quadrature amplitude modulation (16-StQAM) modem is proposed. The 264-kBd 20-slot PRMA scheme supports 36 users while maintaining virtually imperceptible speech degradation for channel SNRs in excess of about 25 dB, and for a mobile speed of 2 mi/h if the signal-to-interference ratio (SIR) is above 30 dB     

Integrated video and voice transmission using packet reservation multiple access

This paper proposes a new protocol for the integration of voice and video transmission over the packet reservation multiple access (PRMA) system that is a modification of reservation‐ALOHA protocol. We focus on low bit‐rate video applications like video conferencing and visual telephony for wireless communications. The ITU–T H.263 standard provides a solution to the need for low bit‐rate video compression under 64 kbytes/s. The proposed protocol assumes that each voice terminal follows a traffic pattern of talk spurts and silent gaps with fixed permission probability (p=0.3), and each video terminal has the higher permission probability (p=1) to access the available slot based on ITU–T H.263 standard. Again, we present a ‘pseudo‐reservation’ scheme to release slots reserved by video terminals according to the contents of each video transmission buffer, and the active voice terminals can temporarily access the additional slots to improve the performance without sacrificing the video capacity of the system. The packet dropping probability of the active voice terminals and bandwidth utilization of the system are superior to the original PRMA, as indicated in simulation results. Copyright © 2001 John Wiley & Sons, Ltd.     

A dynamic packet reservation multiple access scheme for wireless ATM

The dynamic packet reservation multiple access (DPRMA) scheme, a medium access control protocol for wireless multimedia applications, is proposed and investigated. DPRMA allows the integration of multiple traffic types through a single access control mechanism that permits users to specify their immediate bandwidth requirements. The primary feature of DPRMA is the dynamic matching of the traffic source generation rates with the assigned portion of the channel capacity. This is accomplished by a control algorithm that regulates the actual amount of channel capacity assigned to users. To support multimedia communication, channel capacity assignments are prioritized by traffic type. The performance of the scheme is evaluated and the scheme is shown to perform well in a system with voice, video conferencing, and data users present. It is also shown to provide improved performance over a system with a modified version of the packet reservation multiple access (PRMA) scheme. Furthermore, several system parameters are studied and optimized.     

一种适合时分双工环境的分组预约多址协议

对数字式蜂窝移动通信网络,本文提出了时分双工环境下的冲突削弱分组预约多址（CR－PRMA／TDD）协议,并使用平衡点法推导出给定同时通话终端数时的分组丢弃率。计算机仿真结果表明,CR－PRMA／TDD协议可以极大地提高系统的容量。     

C-PRMA: a centralized packet reservation multiple access for localwireless communications

Packet-switched technology has been demonstrated as effective in cellular radio systems with short propagation delay, not only for data, but also for voice transmission. In fact, packet voice can efficiently exploit speech on-off activity to improve bandwidth utilization over time division multiple access (TDMA). Such an approach has been first suggested in the packet reservation multiple-access (PRMA) technique, an adaptation of the reservation ALOHA protocol to the cellular environment. However, being PRMA-based on a fixed frame scheme, it cannot thoroughly take advantage of the very short propagation delays encountered in microcellular systems that allow, for instance, the immediate retransmission of packets lost because of the interference noise from adjacent cells. We present the centralized PRMA, a natural enhancement of PRMA, in which the base station (BS) plays a central role in scheduling the transmissions of mobile stations (MSs). As a consequence, the transmission scheduling is very flexible and can account for the different traffic rate and delay constraints that emerge from voice and data integration. A packet retransmission policy to recover corrupted packets can be implemented and operated efficiently to provide an acceptable grade of service, even in a very noisy environment. The simulation results presented show the quantitative improvements of the centralized packet reservation multiple-access (C-PRMA) performance with respect to PRMA     

A reservation multiple access protocol for microcellularmobile-communication systems

A reservation multiple-access protocol for mobile communications in a microcellular environment is proposed and investigated under high-load conditions, both analytically and by simulation. The reservation scheme proposed uses a reservation channel of the slotted-ALOHA protocol type and an adaptive retransmission probability for stable operation. The capacity of the reservation channel varies with the load above a certain threshold (reservation capacity threshold); in that respect it is a compromise between the R-ALOHA and ALOHA-reservation protocols, both proposed for satellite communications, and the PRMA, an R-ALOHA-type protocol proposed for short-range mobile communication. The access delay is calculated and the optimum reservation capacity threshold is derived to minimize that delay, for specific load conditions     

Idle-signal casting multiple access with data slot reservation(ICMA-DR) for packet radio communications

A population of terminals communicating with a central station over a packet-switched multiple access radio channel is investigated with regard to multiple access control schemes. The authors describe the ICMA-DR, which is an advanced idle-signal casting multiple access (ICMA) scheme characterized by data slot reservation. This improved central controlled multiple-access scheme for packet transmission in terrestrial radio communications is evaluated in terms of throughput traffic, throughput delay characteristics, and handling capacity. It is shown that the throughput characteristics of ICMA-DR are superior than those of ICMA or slotted ALOHA when a packet for data slot reservation is relatively short in comparison to that for upward data. Thus, it is shown that ICMA-DR is suitable for the packet radio multiple-access scheme, especially in the case where fading packet error occurs frequently and ordered traffic is heavy. The ICMA-DR scheme has been utilized for the access control channel of NTT's new 800-MHz-band high-capacity land mobile communication system since the Spring of 1988     

Handoff effect on packet reservation multiple access (PRMA) in microcellular system

Packet reservation multiple access (PRMA) has been proposed for third-generation wireless information networks by D.J. Goodman and S.X. Wei (see ibid., vol.40, p.170-6, 1991). The mobile-initiated handoff has been proposed to disperse the base station (BS) burden, which is increased by the small microcell radius. However, increased contentions, due to handoff, affect the overall performance of PRMA, even though these frequent handoffs do not burden the BS. We analyze the handoff effect on PRMA performance under a microcellular system, both voice-only and combined voice-and-data systems. A steady state voice-terminal model with handoff is proposed. System-equilibrium equations are derived using the proposed model. The system performance is evaluated, using a Markov analysis method, in terms of packet-dropping probability, data-packet delay, and throughput. The change of performance under handoff show the impact of handoff on PRMA.     

无冲突话音/数据综合业务分组预约多址(CF-IPRMA)协议及其性能

本文提出了无冲突话音／数据综合业务的ＰＲＭＡ协议：ＣＦ－ＩＰＲＭＡ协议,并利用马尔可夫链模型法,对ＣＦ－ＩＰＲＭＡ协议中的数据通信性能进行了分析;分析结果表明,该协议在保证话音通信质量的前提下,具有较高的数据业务通过率。     

A packet reservation multiple access (PRMA)-based algorithm for multimedia wireless system

The major issue in the wireless multimedia system design is the selection of a suitable channel sharing media access control (MAC) protocol. The design challenge is to identify a wireless "multimedia capable" MAC protocol that provides a sufficient degree of transparency for many different kinds of services. This protocol should guarantee different quality of service (QoS) parameters for different types of traffic while in the same time achieving high throughput. In this paper a MAC protocol to serve different kinds of traffic, namely voice, data, and, real time variable bit rate (rt-VBR) video is proposed. The transmission time scale is divided into frames. Each frame is subdivided into N time slots. In this protocol, a fixed number of slots M out of 150 time slots are reserved at the beginning of every frame to transmit some of the video packets arriving during the frame interval. The rest of the video packets contend with the voice and data packets for the remaining time slots of this frame as in normal packet reservation multiple access (PRMA). One objective of this paper is to find the optimum value of M allowing the maximum number of voice and data users to share the RF channel with one video user. Another objective is to find the optimum permission probabilities of sending contending voice, data, and video packets allowing the maximum number of users sharing the RF channel. The dropping probability requirement for video is examined.     

Performance of packet reservation multiple access for digital mobile radio using variable rate speech coder

The advantages of using adaptive bit rate voice coders to improve the performance of PRMA for digital cellular radio are considered. It is shown that such a technique forces a fairer distribution of packet loss between mobiles and is able to accommodate fluctuations in traffic levels within a cell.<>     

Capture-division packet access for wireless personal communications

This paper presents a new architecture for the third-generation mobile systems, capture-division packetized access (CDPA), that overcomes most of the limitations of present cellular systems. It addresses the three main issues of radio access, namely the channel reuse, the multiple access, and the handover problems, in complete adherence to packet-switching principles. The CDPA channel reuse mechanism is a completely new alternative with respect to time-division, frequency-division, or code-division multiple-access (TDMA, FDMA, and CDMA, respectively), which achieve communication parallelism by subdividing the bandwidth a priori among cells. In CDPA, a single frequency channel is used and parallel transmissions are achieved through the “capture” capability of receivers. The hybrid reservation-polling multiple access mechanism used in CDPA is able to integrate any kind of traffic and guarantees almost immediate retransmission of packets that are not captured, thus assuring their correct reception. Finally, the packet-switching approach allows connectionless communications with any base station (BS), and eliminates the need for extra radio traffic in managing handovers. This turns out to be very effective in local area systems where the required high bandwidth is obtained by using a pico-cell structure. We present the CDPA architecture, discuss some implementation issues, and evaluate its performance under a variety of system parameters and operating conditions, using analytical and simulation methods     

基于复小波包基函数调制的跳频多址通信系统

该文给出了一种生成复数小波包基函数的方法，提出了一种基于复小波包基函数调制的跳频多址通信系统的模型。该系统在多径衰落时变信道下采用判决反馈均衡器接收的性能与基于实小波包基函数调制的同类系统相比有明显改善，且通过采用空间分集接收，可显著提高系统的误码率性能。该系统易于支持多速率话音和数据业务，具有频谱利用率高，抗单音干扰能力较强和保密性高等优点。     

A multiple access protocol with explicit and implicit reservation

A new version of a MAC‐level protocol is introduced and investigated, operating in a cellular environment, where a base station co‐ordinates mobile users within each cell. The channel multiplexing structure is based on time division, and the slots in each frame are dynamically assigned to the users and their service classes by the cell base station. Decisions are taken on the basis of binary channel feedback information (collision/no collision), by assuming independence in the presence of packets at the mobile stations, and aim at maximizing the one‐step throughput in the current frame. The frame is divided into two periods: the first (short) one contains a number of minislots, equal to the number of ‘real’ slots (i.e. those capable of containing a fixed size packet) of the second part. At the beginning of the frame, the access rights are computed and broadcast to the users; the enabled stations that have a packet to transmit respond, by sending a short burst that contains their ID in a minislot. This most recent feedback is used at the base station to update the parameters of the decision algorithm, which is then re‐applied to yield the final access rights for the second part of the frame. The performance of the scheme is analysed by simulation in the presence of mixed voice and data traffic, and compared with those of a reservation random access protocol using the same algorithm in a single‐phase fashion (RRA‐ISA) and PRMA. Copyright © 2001 John Wiley & Sons, Ltd.     

Packet reservation multiple access for local wirelesscommunications

Simulation work is reported indicating that packet reservation multiple access (PRMA) allows a variety of information sources to share the same wireless access channel. Some of the sources, such as speech terminals, are classified as periodic and others, such as signaling, are classified as random. Packets from all sources contend for access to channel time slots. When a periodic information terminal succeeds in gaining access, it reserves subsequent time slots for uncontested transmission. Both computer simulations and a listening test reveal that PRMA achieves a promising combination of voice quality and bandwidth efficiency     

On the capacity of infinite population multiple access protocols

We present bounds on the maximum channel utilization (with finite average delay) of synchronous multiple access communications protocols serving an infinite population of homogeneous stations. Messages arrive to the system as a series of independent Bernoulli trials in discrete time, with probability p of an arrival at each arrival point (the Poisson limit is explicitly included) and are then randomly distributed among the stations. Pippenger showed that the channel utilization cannot exceedxi_{p}, wherexi_{l}=1andlim_{p rightarrow 0} xi_{p} approx 0.744. Using a "helpful genie" argument, we find the exact capacity for allp geq 0.568(where we find optimal protocols that obey first-come first-served); for smaller values of p, we present an improved upper bound that decreases monotonically toapprox 0.6731in the Poisson limit asp rightarrow 0.     

Stability analysis of an adaptive packet access scheme for mobile communication systems with high propagation delays

In this paper, we investigate a packet access scheme that is able to support mixed traffics in the presence of high propagation delays. Referring to a Time‐Code Division Multiple Access air interface, we propose a Medium Access Control (MAC) protocol based on a random access scheme. A successful attempt grants the use of a slot‐code resource. This protocol is named Adaptive Time Code‐Packet Reservation Multiple Access (ATC‐PRMA), since the access parameters are changed, depending on the traffic load conditions, so as to fulfil Quality of Service requirements. Numerical examples are carried out for the Low Earth Orbit (LEO)‐Mobile Satellite System (MSS) scenario, but all these considerations could be applied to High‐Altitude Platform Stations (HAPSs) as well. In both cases, high propagation delays prevent an immediate feedback to users. An analytical approach is proposed to study the stability of our MAC scheme. Accordingly, we define a criterion for optimizing system performance. The predicted ATC‐PRMA behaviour is supported by simulation results. Finally, we show the performance improvement of ATC‐PRMA with respect to a MAC protocol not employing adaptive parameters. Copyright © 2003 John Wiley & Sons, Ltd.     

自适应动态分组预约多址协议

该文提出一种基于自适应传输的动态分组预约多址协议。用来在业务量和信道都时变的环境下，灵活、高效地支持需要各种不同质量需求的无线多媒体通信。在这个方案中根据特点不同将空闲时隙分为“自由”、“长可用”或“短可用”三种，以“自由”时隙数目作为系统实时业务量的判决标准，根据系统实时业务量分别采用不同的多址接入策略，将长数据和短数据安排在语音传输的空隙传输，同时采用了自适应传输体制来进一步提高系统性能。仿真实验表明，通过合理选择系统参数，可以有效地增加系统总容量。