Enhanced General Packet Radio Service Research Articles

Comparison of Wireless Power Controllers for Induction Aerogenerators Connected to a Smart Grid Based on GPRS and EGPRS Standards

In recent years, wind plants have undergone major changes due to new technologies developed for smart grids (SG). For its success, it becomes necessary the use of modern information and telecommunication infrastructure with bidirectional data flow. In Brazil, due to the high penetration of data networks based on GSM technology (Global System Mobile), such as GPRS (General Packet Radio Service) and EGPRS (Enhanced GPRS), it has attracted the interest of energy companies to carry out the tasks of measurement, monitoring, and control in SG. The use of cellular technology enables at first a significant reduction in the SG deployment costs while providing reliability and security of the information. In this context, the use of a cellular network for monitoring and control data sharing in intelligent wind farms has recently aroused great interest. This work proposes the analysis of a wireless control system based on GPRS and EGPRS data services for variable-speed squirrel-cage induction generators (SCIG) connected to the power grid. The wireless communication system is employed to send the reference power signals to the SCIG controller with the necessary reliability to ensure the power quality provided by the wind turbine. The performance of the proposed system is evaluated by several simulations and tests.

GPRS system enhancement by employing LDPC codes

AbstractWe address the application and design of low‐density parity‐check (LDPC) codes to enhance the General Packet Radio Service (GPRS) system in order to support services such as the Multimedia Broadcast Multicast Service (MBMS). Advances in coding theory and further reduction in integrated circuit size have promoted LDPC codes to become one of the most attractive forward error correction (FEC) technologies in practice. The GPRS as well as enhanced GPRS (EGPRS) system currently uses the well‐known convolutional code (CC) as an FEC mechanism, and the Viterbi algorithm for decoding. With the recent introduction of MBMS, new applications that require more bandwidth and reliability are foreseen. It is known that the current (E)GPRS system does not perform well enough without further modifications, therefore, more efficient information distribution schemes need to be considered. To meet these increased requirements, especially for MBMS, we study the introduction of carefully designed LDPC codes at the physical layer. To exploit the full benefit of the superior performance of LDPC codes for large data block lengths, a modification in the GPRS protocol stack is proposed where larger RLC/MAC blocks are allowed, and its impact on the existing GPRS protocol stack is minimised. Copyright © 2007 John Wiley & Sons, Ltd.

A New Class of Generative Models for Burst-Error Characterization in Digital Wireless Channels

Accurate and efficient generative models are significant for the design and performance evaluation of wireless communication protocols as well as error-control schemes. In this paper, deterministic processes are used to derive a new class of hard and soft generative models for simulation of digital wireless channels with hard and soft decision outputs, respectively. The proposed deterministic-process-based generative models (DPBGMs) are all based on a properly parameterized and sampled deterministic process followed by a threshold detector and two parallel mappers. The target hard and soft error sequences are provided by computer simulations of uncoded enhanced general packet radio service (EGPRS) systems with typical urban and rural area channels. Simulation results indicate that the proposed DPBGMs enable us to approximate very closely all the interested burst-error statistics of the target hard and soft error sequences. The validity of the suggested DPBGMs is further confirmed by the excellent match of the simulated frame-error rates and residual bit-error rates of coded EGPRS systems obtained from the target and generated error sequences

Influence of incremental redundancy on the performance of TCP in enhanced general packet radio service

The incremental redundancy mechanism defined for enhanced general packet radio service (EGPRS) (also known as type-II hybrid ARQ) is considered here. The optimum packet combining strategy is identified and is then used to assess the performance of transmission control protocol/internet protocol in the transmission of bulk data over an EGPRS system. The influence of other key system operating parameters is also assessed and a set of optimal operating parameters is derived and discussed.

Near-optimal signal demodulation method with a special quasi-Gaussian weight function

We consider a GSM cellular communication system using the enhanced general packet radio service (EGPRS) for high-speed information exchange. Transmission is performed by signals with eight-phase-shift keying (8-PSK) modulation with a special quasi-Gaussian weight function. To optimize demodulation of such signals in the presence of Rayleigh fadings, we propose a method using partial measurement of metrics, preliminary estimation of symbols, and decision feedback. We present the results of numerical simulation for the case of a channel with Rayleigh fadings of signals. High efficiency of the proposed method for demodulation of 8-PSK modulated signals is confirmed.

Uncoded Symbol Error Rate Estimation: Methods and Analysis

In wireless communications systems, channel quality estimates are often used to provide a measure of the quality of service or to enable resource allocation techniques that improve system capacity and/or user quality. The uncoded bit or symbol error rate (SER) is specified as a channel quality metric in second and third generation cellular systems (e.g., general packet radio service (GPRS), enhanced general packet radio service (EGPRS), and universal mobile telecommunications system (UMTS). Nonetheless, techniques to estimate the uncoded SER are typically outside the scope of these wireless standards and are not specified. In this paper, we analyze the performance of a number of uncoded SER estimation techniques, including a novel technique in which we use the soft information of the received symbols to obtain a fast and accurate estimate of the uncoded SER. The technique we introduce has been found to outperform, in terms of accuracy and required estimation interval, conventional hard-decision based techniques that use test-patterns, or use a decode/re-encode/compare approach . Our technique also outperforms the brute-force technique, which is to send a known test-pattern, demodulate it at the receiver, and count the observed discrepancies.

Low-complexity MMSE turbo equalization: a possible solution for EDGE

This paper deals with a low complexity receiver scheme where equalization and channel decoding are jointly optimized in an iterative process. We derive the theoretical transfer function of the infinite length linear minimum mean square error (MMSE) equalizer with a priori information. A practical implementation is exposed which employs the fast Fourier transform (FFT) to compute the equalizer coefficients, resulting in a low-complexity receiver structure. The performance of the proposed scheme is investigated for the enhanced general packet radio service (EGPRS) radio link. Simulation results show that significant power gains may be achieved with only a few (3-4) iterations. These results demonstrate that MMSE turbo equalization is an attractive candidate for single-carrier broadband wireless transmissions in long delay-spread environments.

Performance analysis of reservation media-access protocol with access and serving queues under bursty traffic in GPRS/EGPRS

Performance modeling of the contention-based reservation protocol in the general packet radio service (GPRS)/enhanced GPRS (EGPRS) under bursty traffic is of practical use in system design. Instead of using discrete event simulation, we construct an analytical model based on stochastic Petri net formalism to investigate GPRS uplink performance efficiently. The model is built to capture the major features of a realistic system, taking into account factors such as the traffic profile, the system's capture capability, the contention persistence, the multislot capability, and the use of the access queue and the round-robin virtual serving queue. As shown in numerical results, these factors have different impacts on the performance measures, such as link-control-layer frame-blocking probability, frame delay, system throughput, and packet-channel utilization. To avoid modeling and computational complexity in a GPRS/EGPRS system model that supports several mobile terminals, we make first-order approximations and use an iterative fixed-point scheme. Comparisons with discrete event simulations are conducted and show promising agreement with the proposed analytical-numerical model. We then use the model to investigate GPRS packet-data performance under different parameter settings and present numerical results, providing insights into network design and optimization.

A proposal for EGPRS radio link control using link adaptation and incremental redundancy

Standardization is currently in progress to specify Enhanced Data rates for GSM Evolution (EDGE). The two components of EDGE, Enhanced Circuit-Switched Data (ECSD) and Enhanced General Packet Radio Service (EGPRS), define enhancements for circuit-mode and packet-mode data, respectively. EGPRS is also intended to provide a high-rate North American digital time division multiple access (TDMA) packet data service. To achieve higher data rates, 8-ary phase shift keying (8-PSK) modulation has been introduced. Enhanced radio link control (RLC) procedures are being defined based on link adaptation and incremental redundancy to achieve superior delay/throughput performance over a wide range of operating conditions. This paper describes a candidate proposal for (RLC) block segmentation for EGPRS that provides combined link adaptation and incremental redundancy; short, fixed-length blocks to achieve lower block error rates; seamless transition between coding schemes without loss in throughput; segmentation to provide a robust Gaussian minimum shift keying (GMSK) fallback mode; and short and extended header formats. We present performance tradeoffs for the proposed scheme. Many of the features of this proposal have been included in the EGPRS specification. We provide a brief description of the block and header formats being standardized.

An overview of EGPRS: the packet data component of EDGE

The explosive growth of the Internet and the subsequent demand for wireless data communications have led to data services being a major component in the standardisation process of many cellular mobile radio systems across the world. In GSM, the standardisation of the first phase of a new data service, initiated by the European Telecommunications Standards Institute (ETSI) and collectively known as Enhanced Data rates for GSM Evolution (EDGE), was finalised in 1999. The Enhanced Circuit Switched Data (ECSD) and Enhanced General Packet Radio Service (EGPRS) components of EDGE will enhance the existing GSM circuit-switched and packet-switched data services, respectively. This paper provides an overview of EGPRS and its performance.

Network-assisted resource management for wireless data networks

We propose a framework for network-assisted radio resource management in wireless data networks. This type of radio resource management techniques offer implementation and capacity benefits compared to conventional, interference-measurement based, dynamic channel assignment (DCA) algorithms. The basic idea is to use interbase signaling to shift most of the burden of the resource allocation from the air interface to the backbone infrastructure. By exchanging channel assignment as well as other relevant information in real time through the backbone network, each base can calculate the impact of a resource assignment on the system. As a result, rapid interference measurements, which are typically needed to implement DCA schemes, are replaced by a limited amount of path loss measurements and the computation of interference conditions by the base stations. This significantly reduces the measurement and over-the-air signaling requirements, and can also provide an opportunity for a better optimization of the system performance. We focus on two specific algorithms: network-assisted least-interference-based dynamic packet assignment (NA-LI-DPA) and network-assisted dynamic packet assignment with throughput optimization (NA-DPA). NA-LI-DPA closely resembles a least-interference-based dynamic channel assignment algorithm, and NA-DPA attempts to further improve the overall system throughput. The algorithms, as defined, are appropriate for a best-effort data service, where the primary goal is to provide a higher throughput. However, it will be clear from the discussion that it is also feasible to alter the algorithms to optimize performance metrics other than throughput, e.g., to ensure a certain quality of service. We show through simulation that, for a system like enhanced general packet radio service (EGPRS) system, NA-DPA can provide a throughput that is 50% higher than random packet assignment, and 25% higher than that obtained by conventional DCA algorithms.

Link adaptation and power control for streaming services in EGPRS wireless networks

Using the MPEG-4 advanced audio coder (AAC) music as an example of streaming applications, we investigate the improvement of error performance for the streaming service by link adaptation and power control techniques in an enhanced general packet radio services (EGPRS) cellular network. A low packet error rate and variability are essential in providing a short error-burst length so that error concealment techniques can be effectively applied to music packets. We study the effects of a combined link adaptation and power control scheme (referred to as the error-based scheme) for achieving a target error rate and reducing error variability. By simulation, we compare the error performance of the error-based scheme at both the EGPRS block and AAC frame level with another adaptation algorithm (referred to as the throughput-based scheme) with a goal of maximizing overall network throughput. It is found that when offered with a similar traffic load, the former scheme can provide noticeable improvement of music quality over the throughput-based scheme. To achieve a similar AAC frame error rate, our results also show that the error-based scheme can increase the link throughput over the throughput-based scheme by 66.7% in one of our examples. These results reveal that by aiming at required error targets and thus reducing error variability, the error-based scheme for link adaptation and power control are helpful in improving quality and capacity for streaming applications.