Delay analysis of selective-repeat ARQ with applications to link adaptation in wireless packet data systems

Radio link control (RLC) protocols are typically employed for reliable in-sequence delivery of service data units (SDUs) in wireless packet data systems. The RLC layer segments packets obtained from the upper layer (referred to as SDUs) into smaller RLC transmission units (or blocks) and uses selective-repeat automatic repeat request (SR-ARQ) for error recovery of RLC blocks. In earlier work, SR-ARQ performance is typically characterized in terms of the long-term throughput or in-sequence delivery delay of RLC blocks. The SDU delivery delay which is a more meaningful measure of RLC performance (in terms of the service provided to a higher layer, e.g., transmission control protocol) has not been quantified. In this paper, we analyze the SDU delivery delay of SR-ARQ as a function of the SDU size and the channel coding scheme employed. Closed-form delay expressions as well as approximations are provided. The analysis is verified through enhanced general packet radio service RLC simulations. Based on the analysis, we propose that link adaptation be backlog dependent in order to reduce the SDU delivery delay at the RLC layer.     

Concepts, services, and protocols of the new GSM phase 2+ generalpacket radio service

For almost three years the European Telecommunications Standards Institute (ETSI) has been working on the specification of the general packet radio service (GPRS) for the Global System for Mobile Communications (GSM). In the course of 1997 standardization will come to an end, and a first introduction of GPRS by a service provider or network operator is likely to take place in 1999. The new service will accommodate data connections with variable bit rates and high bandwidth efficiency, and thus offers the possibility to attract a wide range of new applications to GSM networks. In this article possible applications and elementary concepts and service characteristics of GPRS are explained in detail. Furthermore, a medium access control protocol that conforms to the draft standard proposal for the GPRS air interface is introduced and analyzed. Thereafter, the simulation model is described and simulation results presented. The performance analysis carried out shows reasonable performance even under high load conditions     

Efficiency of the GSM-GPRS Air Interface for Real-Time IP Traffic Flows With and Without Packet Dropping

One IP terminal can occupy a single slot or a multiple number of slots within time frames in the GSM and GPRS, respectively. A limited number of radio resources (slots) are allocated in a base station for such IP terminals. If one IP terminal can occupy only one slot discontinuously in a time frame, there is one possibility resorting to all IP terminals to preserve active mode at a time. Thus, the number of accepted call in the GSM is the same as that of the radio resource. Similarly, if one terminal can occupy a multiple number of slots discontinuously/dynamically in a time frame, the number of accepted calls is obtained by dividing the number of radio resources during that time by the maximum allowed number of slots per IP terminal. A burstiness factor is defined for the IP traffic over GSM-GPRS air interface. Traffic channel efficiency with a bursty real-time IP traffic is unacceptably low, especially with the range of acceptable call loss probabilities pertaining to a lower burstiness factor. The channel efficiency can be enhanced and the call loss probability can be suppressed significantly if a higher maximum number of calls is accepted. Allocated radio resources are less than the maximum number of packet transmissions at a time. Therefore, some packets could be dropped from the real-time transmission system. A complete analysis for the real-time IP packet transmission over the single slot GSM and dynamically variable multislot GPRS air interface without packet dropping, and with packet dropping that increases the channel efficiency is executed. Results show that the channel efficiency as well as the packet dropping probability increases with increasing call intensity, maximum number of admitted IP calls and the burstiness factor.     

End-to-End Adaptive QoS Provisioning over GPRS Wireless Mobile Network

The General Packet Radio Service (GPRS) offers performance guaranteed packet data services to mobile users over wireless frequency-division duplex links with time division multiple access, and core packet data networks. This paper presents a dynamic adaptive guaranteed Quality-of-Service (QoS) provisioning scheme over GPRS wireless mobile links by proposing a guaranteed QoS media access control (GQ-MAC) protocol and an accompanying adaptive prioritized-handoff call admission control (AP-CAC) protocol to maintain GPRS QoS guarantees under the effect of mobile handoffs. The GQ-MAC protocol supports bounded channel access delay for delay-sensitive traffic, bounded packet loss probability for loss-sensitive traffic, and dynamic adaptive resource allocation for bursty traffic with peak bandwidth allocation adapted to the current queue length. The AP-CAC protocol provides dynamic adaptive prioritized admission by differentiating handoff requests with higher admission priorities over new calls via a dynamic multiple guard channels scheme, which dynamically adapts the capacity reserved for dealing with handoff requests based on the current traffic conditions in the neighboring radio cells. Integrated services (IntServ) QoS provisioning over the IP/ATM-based GPRS core network is realized over a multi-protocol label switching (MPLS) architecture, and mobility is supported over the core network via a novel mobile label-switching tree (MLST) architecture. End-to-end QoS provisioning over the GPRS wireless mobile network is realized by mapping between the IntServ and GPRS QoS requirements, and by extending the AP-CAC protocol from the wireless medium to the core network to provide a unified end-to-end admission control with dynamic adaptive admission priorities.     

GPRS网络RLC层应答模式性能分析

分析了RLC/MAC层在应答模式下的工作过程和性能特点,对应答引起的时延进行了理论分析。并介绍一种基于FEC/ARQ的改进机制,它将有助于减少用于RLC应答的控制数据块,从而达到减少数据传送的时延和增加数据吞吐量的目的。     

Channel de-allocation schemes for GSM/GPRS networks

Several channel de-allocation schemes for GSM/GPRS（General Packet Radio Service） networks are proposed in this paper. For DRA （Dynamical Resource Allocation） with de-allocation mechanism, if a new voice call arrives and finds that all the channels are busy, then one of the GPRS packets which occupy more than one channel for data transmission may release a channel for the new voice call. This paper presents 5 de-allocation mechanisms, i.e. DA-RANDOM, DA-RICHEST, DA-POOREST, DA-OLDEST and DA-YOUNGEST, to select the GPRS packet for releasing the appropriate channel. Simulation results show that DA-OLDEST achieves the best performance, especially in packets blocking probability, among all the de-allocation schemes. Although the performance of the proposed de-allocation schemes is not significantly different, they are all much better than that of the scheme without de-allocation.     

Performance analysis of channel de-allocation schemes for dynamic resource allocation in GSM/GPRS networks

Channel de-allocation for GSM voice call (DASV) has been considered for dynamic resource allocation in GSM/GPRS networks. Two new de-allocation schemes are proposed: de-allocation for GPRS packet (DASP) and de-allocation for both GSM voice call and GPRS packet (DASVP). An analytic model with general GPRS data channel requirement is derived to evaluate the performance of the schemes in terms of GSM voice call incompletion probability, GPRS packet dropping probability, average GPRS packet transmission time and channel utilisation.     

vGPRS: A Mechanism for Voice over GPRS

This paper proposes vGPRS, a voice over IP (VoIP) mechanism for general packet radio service (GPRS) network. In this approach, a new network element called VoIP mobile switching center (VMSC) is introduced to replace standard GSM MSC. Both standard GSM and GPRS mobile stations can be used to receive real-time VoIP service, which need not be equipped with the VoIP (i.e., H.323) terminal capabilities. The vGPRS approach is implemented using standard H.323, GPRS, and GSM protocols. Thus, existing GPRS and H.323 network elements are not modified. Furthermore, the message flows for vGPRS registration, call origination, call release and call termination procedures are described to show the feasibility of our vGPRS system.     

请求计时到引起手机WAP接入失败的协议分析

针对请求计时到引起GPRS网络中手机WAP接入失败的情况,从WAP协议栈中的WSP协议层、WTP协议层、GPRSRLC/MAC协议层以及GSMUm接口第三层对同时在GPRSGb接口和GSMUm接口采集到的消息进行了关联的协议分析。分析结果表明,请求计时到引起GPRS网络中手机WAP接入失败是由于在超时重传消息过程中手机侧的WTP协议层无响应所致,与GPRS无线承载网络及GSMUm接口无关。     

Channel Allocation for GPRS with Buffering Mechanisms

General Packet Radio Service (GPRS) provides mobile users end-to-end packet-switched services by sharing the radio channels with voice and circuit-switched services. In such a system, radio resource allocation for circuit-switched and packet-switched services is an important issue, which may affect the QoS for both services significantly. In this paper, we propose two algorithms: Dynamic Resource Allocation with Voice and Packet queues (DRAVP) and Dynamic Resource Allocation with Packet and Voice queues (DRAPV) for channel allocation of the voice calls and packets. We propose analytic and simulation models to investigate the performance of DRAVP and DRAPV in terms of voice call incompletion probability, packet dropping probability, average voice call waiting time, and average packet waiting time. Our study indicates that the buffering mechanism for GPRS packets significantly increase the acceptance rate of GPRS packets at the cost of slightly degrading the performance of voice calls.     

General Packet Radio Service (GPRS): architecture,interfaces, and deployment

This article provides an overview of General Packet Radio Service (GPRS). GPRS reuses the existing GSM infrastructure to provide end‐to‐end packet‐switched services. Benefits of GPRS include efficient radio usage, fast set‐up/access time and high bandwidth with multiple timeslots. GPRS also provides a smooth path for GSM evolution to the third generation mobile network. Specifically, a third generation network can continue to utilize the GPRS IP backbone network. We describe the GPRS network nodes and the interfaces among these nodes. Deployment issues for GPRS are also elaborated. Copyright © 2001 John Wiley & Sons, Ltd.     

Channel allocation for GPRS

Based on the GSM radio architecture, the general packet radio service (GPRS) provides users data connections with variable data rates and high bandwidth efficiency. In the GPRS service, allocation of physical channels is flexible, i.e., multiple channels can be allocated to a user. We propose four algorithms for the GPRS radio resource allocation: fixed resource allocation (FRA), dynamic resource allocation (DRA), fixed resource allocation with queue capability (FRAQ), and dynamic resource allocation with queue capability (DRAQ). We develop analytic and simulation models to evaluate the performance for these resource allocation algorithms in terms of the acceptance rate of both GPRS packet data and GSM voice calls. Our study indicates that DRAQ (queuing for both new and handoff calls) outperforms other algorithms     

Performance analysis of RLC/MAC and LLC Layers in a GPRS protocol stack

In this paper, we analyze the performance of various layers of the general packet radio service (GPRS) protocol stack, including radio link control/medium-access control (RLC/MAC) layer and logical link-control (LLC) layer on the uplink. In the GPRS MAC protocol, several time-slotted uplink radio-frequency channels are shared by the mobiles on a request-reservation-based multiple-access scheme. Using the theory of Markov chains, we derive expressions for the average throughput and delay performance of the GPRS MAC protocol. We evaluate the performance of the RLC layer (in acknowledged mode) using block-level retransmission (BLR), as defined in the current GPRS standard, and compare it with that of using slot-level retransmission (SLR). We show that SLR at the RLC layer performs significantly better than the BLR, particularly when the channel-error rates are moderate to high. We further investigate the choice of parameters (e.g., number of retransmission attempts) for the automatic repeat request schemes at the RLC and LLC layers. Our results show that it is more beneficial to do error recovery by allowing more retransmission attempts at the RLC layer than at the LLC layer. We also evaluate the performance of transmission-control protocol with BLR and SLR at the RLC layer.     

Improving CS-4 User Data Rate in GPRS Enabled Devices by Using a BLER Co-processor

The General Packet Radio Service (GPRS) was developed to allow packet data to be transported efficiently over an existing circuit switched radio network. The main applications for GPRS are in transporting IP datagram’s from the user’s mobile Internet browser to and from the Internet, or in telemetry equipment. A simple Error Detection and Correction (EDC) scheme to improve the GPRS Block Error Rate (BLER) performance is presented, particularly for coding scheme 4 (CS-4), however gains in other coding schemes are seen. For every GPRS radio block that is corrected by the EDC scheme, the block does not need to be retransmitted releasing bandwidth in the channel, improving throughput and the user’s application data rate. As GPRS requires intensive processing in the baseband, a viable hardware solution for a GPRS BLER co-processor is discussed that has been currently implemented in a Field Programmable Gate Array (FPGA) and presented in this paper.When this work was completed and now Kai Zhang is with Current affiliation: Beijing Kedong Power Control System Co. Ltd.When this work was completed and now Owen J. Wilkes is with Current affiliation: Aculab.     

Comparison of Hop-By-Hop and End-To-End Acknowledgment Schemes in Computer Communication Networks

The problem of acknowledgment schemes in store-and-forward packet-switching communication networks is addressed. The performance of systems with end-to-end acknowledgment (ETE Ack) and hop-by-hop acknowledgment (HBH Ack) are compared in terms of packet delay and channel utilization. It is shown that a system with an HBH Ack scheme performs significantly better in terms of delay or channel utilization, when the number of hops that a packet traverses is large and/or when the probability of successful packet transmission over the channel is low.     

A bandwidth-on-demand strategy for GPRS

General packet radio service (GPRS) is a global system for mobile communications (GSM) packet data service. In order to efficiently accommodate GPRS traffic while maintaining the desired service quality of GSM calls, we propose a GPRS bandwidth-allocation strategy called the bandwidth-on-demand (BoD) strategy. The BoD strategy is adaptive to the change of traffic conditions, and thus can dynamically adjust the number of channels for GSM and GPRS traffic. Taking the effect of packet dropping due to movements of mobile stations into account, this paper develops an analytical model to study the BoD performance in terms of GSM-call-blocking probability and GPRS-packet-dropping probability.     

GPRS random access channel performance over the Geostationary Mobile Satellite Standard

The performance of the General Packet Radio Service (GPRS) random access channel as applied to the newly proposed Geostationary Mobile Satellite Standard (GMSS) is analysed. This standard adapts the GSM air interface to a geostationary satellite network. The channel is studied using analytical techniques. Copyright © 2001 John Wiley & Sons, Ltd.     

UMTS分组域与GSM/GPRS系统间切换过程中数据缓存与转移的实现与分析

首先介绍了UMTS中的几种切换类型,然后就UMTS分组域到GSM/GPRS系统间切换(SGSN间),GSM/GPRS到UMTS分组域系统间切换(SGSN间),UMTS分组域到GSM/GPRS系统间切换(SGSN内),GSM/GPRS到UMTS分组域系统间切换(SGSN内)这4种切换过程中的数据缓存与转移的实现过程进行了详细论述,并进行了进一步深入的分析与比较,最后指出其优缺点。     

GPRS若干关键技术的分析与研究

通用分组无线业务（General Racket Radio Service,GPRS）作为GSM网络新的承载服务,解决了传统GSM网中数据传递慢、计费方式单一的缺点,本文重点是对GPRS移动性管理和无线资源分配做了详细分析,并对GPRS计费原则做了进一步的研究。