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 Medium Access Control Protocol for Voice/Data Integrated Wireless CDMA Systems

In this paper, a medium access control protocol is proposed for integrated voice and data services in wireless local networks. Uplink channels for the proposed protocol are composed of time slots with multiple spreading codes per slot based on slotted code division multiple access (CDMA) systems. The proposed protocol uses spreading code sensing and reservation schemes. This protocol gives higher access priority to delay‐sensitive voice traffic than to data traffic. The voice terminal reserves an available spreading code to transmit multiple voice packets during a talkspurt. On the other hand, the data terminal transmits a packet without making a reservation over one of the available spreading codes that are not used by voice terminals. In this protocol, voice packets do not come into collision with data packets. The numerical results show that this protocol can increase the system capacity for voice service by applying the reservation scheme. The performance for data traffic will decrease in the case of high voice traffic load because of its low access priority. But it shows that the data traffic performance can be increased in proportion to the number of spreading codes.     

Performance analysis of a PRMA protocol suitable for voice and datatransmissions in low Earth orbit mobile satellite systems

Mobile satellite systems (MSSs) are expected to play a significant role in providing users with communication services worldwide. In such a context, low Earth orbit (LEO) satellite constellations seem to be a good solution to attain a global coverage and to allow the use of low-power lightweight mobile terminals. This paper analyzes the performance of a novel medium access control (MAC) scheme suitable for applications in LEO-MSSs, named packet reservation multiple access with hindering states (PRMA-HS), that has been derived by proper modifications of the well-known PRMA protocol. We envisage a mixed traffic with voice sources and data sources with different quality of service (QoS) requirements. The good behavior of the proposed PRMA-HS scheme is validated by extensive comparisons with the classical PRMA protocol. Finally, it is shown that PRMA-HS efficiently supports integrated voice and data traffic in LEO-MSSs     

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.     

Dynamic Reservation Multiple Access (DRMA): A new multiple access scheme for Personal Communication System (PCS)

To improve the spectrum efficiency of integrated voice and data services in Personal Communication System (PCS), several reservation-type multiple access schemes, such as Packet Reservation Multiple Access (PRMA), Dynamic Time Division Multiple Access (D-TDMA), Resource Auction Multiple Access (RAMA), etc., have been proposed. PRMA uses the data packet itself to make a channel reservation, and is inefficient in that each unsuccessful reservation wastes one slot. However, it does not have a fixed reservation overhead and offers shorter access delay. On the other hand, fixed reservation overhead is unavoidable in both RAMA and D-TDMA. Compared to D-TDMA and PRMA, RAMA is superior in the sense that its slot assignment is independent of the traffic load. But its implementation is difficult. With these observations, a new reservation protocol, called Dynamic Reservation Multiple Access (DRMA), is proposed in this paper. With this new protocol, the success probability of channel access is greatly improved at the expense of slightly increased system complexity. It solves the problem of inefficiency in PRMA, but without introducing the fixed reservation overhead as in D-TDMA and RAMA. In addition, it is more suited to the dynamic behavior of the integrated traffic because there is no fixed boundary between voice and data slots (which is mandatory in D-TDMA and RAMA). Our numerical results indicate that its performance is superior to the existing reservation protocols, especially in the integrated traffic scenario. Moreover, the soft capacity feature is exhibited when the traffic load increases.     

Voice and data transmissions with a PRMA-like protocol in highpropagation delay cellular systems

Future mobile communication systems will require new medium access control protocols to attain an efficient multiplexing of different traffic sources while guaranteeing their requirements on quality of service. This paper investigates the performance of a modified packet reservation multiple access (PRMA) protocol, called PRMA with hindering states (PRMA-HS), for supporting voice and data transmissions in mobile cellular systems with high propagation delays. A scenario based on low Earth orbit mobile satellite systems (LEO-MSSs) has been considered, but the analytical approach is general. We have obtained that PRMA-HS achieves a high capacity of voice sources in LEO-MSSs also in the presence of data traffic. A performance analysis has been carried out showing good agreement with simulation results. Finally, the PRMA-HS performance has been evaluated in the presence of different data traffic sources     

D-RMA: a dynamic reservation multiple-access protocol for thirdgeneration cellular systems

A dynamic reservation multiple access (D-RMA) protocol for third generation cellular mobile radio systems is proposed and its behavior is investigated under variable multimedia traffic conditions. D-RMA is a protocol which is explicitly designed to support multimedia traffic. Its structure is based on traditional PRMA++ protocol, but in addition to what PRMA++ provides, it introduces a flexible dynamic approach in the choice of the percentage of bandwidth to be used for reservation. Separation between reservation and information channels, along with dynamic adaptation of the percentage of reservation bandwidth within a frame to traffic condition, guarantee the required QoS to multimedia services. Results obtained show that the performance of D-RMA are superior when compared to a traditional “nondynamic” protocol, in terms of both the offered quality of service (QoS) and number of connections which can be activated in a microcell at one time     

Fuzzy/neural congestion control for integrated voice and dataDS-CDMA/FRMA cellular networks

The paper proposes congestion control using fuzzy/neural techniques for integrated voice and data direct-sequence code division multiple access/frame reservation multiple access (DS-CDMA/FRMA) cellular networks. The fuzzy/neural congestion controller is constituted by a pipeline recurrent neural network (PRNN) interference predictor, a fuzzy performance indicator, and a fuzzy/neural access probability controller. It regulates the traffic input to the integrated voice and data DS-CDMA/FRMA cellular system by determining proper access probabilities for users so that congestion can be avoided and the throughput can be maximized. Simulation results show that the DS-CDMA/FRMA fuzzy/neural congestion controllers perform better than conventional DS-CDMA/PRMA with channel access function in terms of voice packet dropping ratio, corruption ratio, and utilization. In addition, the neural congestion controller outperforms the fuzzy congestion controller     

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 simple distributed PRMA for MANETs

With the rapid development of Global Positioning System (GPS) technology and its applications, synchronization between terminals in mobile ad hoc environments becomes feasible at a low cost. Thus, slotted-channel-based medium access control (MAC) schemes like time division multiple access (TDMA) also become interesting for mobile ad hoc networks (MANETs). In this paper, we extend the classical centralized and slotted packet reservation multiple access (PRMA) scheme to a simple distributed PRMA (D-PRMA) as a MAC scheme for MANETs, with emphasis on voice application support. The major efforts of D-PRMA include 1) a simple slot reservation mechanism for voice traffic at the level of "talkspurt" without relying on any central entity and 2) a simple solution for the hidden and exposed terminal problems uniquely present in wireless ad hoc environments. The performance of D-PRMA has been investigated by analysis and computer simulations in comparison with IEEE 802.11. The results show that D-PRMA is much more suitable than IEEE 802.11 for voice application     

A new protocol for the integration of voice and data over PRMA

In packet reservation multiple access (PRMA) the receiver in the mobile terminal is required to listen continuously to monitor the acknowledgment messages broadcasted at the end of every time slot. A new scheme for the integration of voice and data based on PRMA is proposed. The voice and the data subsystems are logically separated. The total available bandwidth is divided into three regions-voice information, voice contention, and data regions. The available bandwidth is dynamically partitioned between the above three regions subject to the fulfillment of the quality of service (QoS) requirements of the voice users. The voice subsystem has been modeled as a Markov chain and an exact analytical method used to compute the voice packet dropping probability is described. A nonlinear programming problem is formulated to optimize the bandwidth allocated for the data users. Solutions to this nonlinear programming problem that are very close to optimum have been obtained heuristically. Numerical results indicate that a significant amount of data traffic can be supported without sacrificing the voice capacity of the system     

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     

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     

Packet Reservation Window Multiple Access for Microcellular Voice/Data Transmission

We propose a new packet reservation multiple access (PRMA) scheme for the joint transmission of voice and data traffics in a microcellular medium. The collision resolution protocol within the system is based on a modification of the window random access algorithm, which has superior properties compared to the conventional slotted Aloha. The proposed algorithm, which we call packet reservation window multiple access (PRWMA), works in distinct modes for voice and data without prioritization, and the user performs slightly different operations depending on the information type. Simulation results show that PRWMA outperforms PRMA by a significant margin in terms of voice user capacity.     

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.     

Block Reservation Time Division Multiple Access (BRTDMA) Protocol for a High Capacity Wireless Network

Next generation high capacity wireless networks need to support various types of traffic, including voice, video and data, each of which have different Quality of Service (QoS) requirements for successful transmission. This paper presents an advanced reservation packet access protocol BRTDMA (Block Reservation Time Division Multiple Access) that can accommodate voice and data traffic with equal efficiency in a wireless network. The proposed BRTDMA protocol has been designed to operate in a dynamic fashion by allocating resources according to the QoS criteria of voice and data traffic. Most of the existing reservation protocols offers reservation to voice traffic while data packets are transmitted using contention mode. In this paper we propose a block reservation technique to reserve transmission slots for data traffic for a short duration, which minimizes the speech packet loss and reduce the end-to-end delay for wireless data traffic. The optimum block reservation length for data traffic has been studied in a cellular mobile radio environment using a simulation model. Simulation results show that the BRTDMA protocol offers higher traffic capacity than standard PRMA protocol for integrated voice and data traffic and offers flexibility in accommodating multimedia traffic.     

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     

Contention‐free approaches for WiFi MAC design for VoIP services: performance analysis and comparison

The exponential growth in the demand of voice over internet protocol (VoIP) services along with the increasing demand for mobility in VoIP services has attracted great research efforts towards provisioning of VoIP services in IEEE 802.11‐based Wireless LANs (WiFi networks). We address one of the important research problems, namely, the quality of service (QoS)‐aware efficient silence suppression in the bursty voice traffic, for provisioning VoIP services in WiFi networks. The research works in the recent literature on silence suppression in voice calls have been surveyed categorising them on how the activity arrival is notified to the access point (AP). In most of the recent schemes, notification of uplink activity arrival is done through contention based medium access mechanisms such as the distributed coordination function (DCF). Contention‐based medium access causes non‐deterministic delays, therefore such schemes are not suited to voice traffic which require strict delay bound guarantees. This paper focuses on the schemes which do not use contention based approaches for silence suppression in voice traffic. Analytical performance evaluation and comparison of such schemes is carried out. Two very important performance metrics are modelled mathematically. One is the expected polling overhead time that the schedulers in these schemes can save per voice call during one voice activity cycle as compared to that in the round‐robin polling scheduler. The other is the expected unnecessary wireless channel access delay that a typical first talk‐spurt frame experiences due to the specific design of each scheme. The numerical results of this evaluation lead us to the conclusion whether or not and to what extent each of these schemes is viable. Copyright © 2008 John Wiley & Sons, Ltd.     

The RRA‐ISA multiple access protocol with and without simple priority schemes for real‐time and data traffic in wireless cellular systems

A multiple access protocol, based on a Reservation Random Access (RRA) scheme, is derived for a wireless cellular network carrying real-time and data traffic. Given a TDMA framed channel and a cellular structure, the aim of the protocol is that of maximizing the one-step throughput over an entire frame. This is achieved by deciding on the access rights at the cell base station, which then broadcasts this information at the beginning of the frame. The decision is made on the basis of binary channel feedback information (collision/no collision) over the previous frames, as well as of long term averages of packet generation rates at the mobile stations, assuming independence in the presence of packets at the latter. The resulting protocol has therefore been termed Independent Stations Algorithm (ISA), and the overall scheme RRA-ISA. As in other RRA protocols, time constrained (e.g., voice) traffic operates in a dynamic reservation mode, by contending for a slot in the frame with the first packet of a burst, and then keeping the eventually accessed slot for the duration of the burst; packets of the time constrained traffic unable to access a slot within a maximum delay are dropped from the input buffer. No such constraint is imposed on data traffic. Together with the “basic” version of the access algorithm, three other variants are presented, which exploit three simple different priority schemes in the RRA-ISA “basic” structure, in order to give a prominence to the voice service. The aim of these variants is to improve the performance in terms of the maximum number of stations acceptable in the system, by slightly increasing the data packets delay. All the proposed schemes are analyzed by simulation in the presence of voice and data traffic. Several comparisons show a relevant performance improvement (in terms of data delay and maximum number of voice stations acceptable within a cell) over other protocols that use ALOHA as a reservation mechanism (RRA-ALOHA or PRMA schemes). This revised version was published online in June 2006 with corrections to the Cover Date.     

A novel self‐adaptive transmission scheme over an IEEE 802.11 WLAN for supporting multi‐service

The IEEE 802.11 wireless local area network (WLAN) media access control (MAC) specification is a hybrid protocol of random access and polling when both distributed coordination function (DCF) and point coordination function (PCF) are used. Data traffic is transmitted with the DCF, while voice transmission is carried out with the PCF. Based on the performance analysis of the MAC protocol for integrated data and voice transmission by simulation, this paper puts forward a self‐adaptive transmission scheme to support multi‐service over the IEEE 802.11 WLAN. The simulation results show that, on the premise of satisfying the maximum allowable delay of packet voice, the self‐adaptive transmission scheme can improve the data traffic performance and increase the WLAN capacity through dynamic and appropriate adjustment of the protocol parameters. Especially, voice traffic is sensitive to delay jitter, and the self‐adaptive scheme can effectively decrease it. Finally, it is worth noting that the adaptive scheme is easy to be realized, whereas no change in the MAC protocol is needed. Copyright © 2006 John Wiley & Sons, Ltd.