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The throughput and spectral efficiency for random access systems over a large code division multiple-access (CDMA) channel is analyzed and an approach that uses retransmission diversity (RD) is proposed. The analysis has highlighted the throughput difference between with and without RD exploitation in different system settings.

The fairness concept has been widely studied in the area of data networks. The most well-known fairness criterion (max-min fairness) gives priority to the minimum-rate session. Kelly questioned its appropriateness in his works on the bandwidth sharing among the end-to-end flows and proposed another fairness criterion preferring short-distance flows to enhance the overall throughput, which is called the proportional fairness (PF). A simple scheduler achieving this objective was introduced in wireless access networks and revealed that it can achieve a good compromise between cell throughput and user fairness. Although it has received much attention for some rime, research on its performance mainly depended on computer simulations. In this paper, we analyze the PF scheduler to obtain the cell throughput, which is a primary-performance metric, and extend the result to analyze the capacity of multiple-input-multiple-output systems. We evaluate the effect of various parameters on the throughput of the PF scheduler through the numerical analysis. Index Terms--Cell throughput, opportunistic scheduler, proportional fair scheduler.

In this paper, we study a large network of subscriber stations (SSs) with certain common wireless capabilities and base stations (BSs) having direct connections to the wired infrastructure in addition to common wireless capabilities. SSs can communicate with the 'outside world' only through the BSs. Connections to SSs without a direct (i.e., a single hop) wireless connection to any BS are established, if possible, through other SSs serving as wireless repeaters. The locations of the SSs and the BSs follow independent homogeneous planar Poisson processes. The propagation channels exhibit signal attenuation with distance and log-normal shadowing. We evaluate exactly the probability of an SS to have a direct wireless connection to any of the BSs and a lower bound on the t-hop (t arbitrary) outage probability of an SS. We then define the minimal hop-count routing algorithm and calculate the mean number of hops for routes connecting SSs to BSs, when a maximum hop-count constraint is imposed. We compute next the probability distribution of the transmit power under the assumption of perfect power control. We conclude by calculating a bound for the total mean transmit energy required to transfer a data packet from an SS to a BS over a minimal hop-count route and show that this energy is significantly lower than the corresponding value in a single-hop network operating at the same outage probability. Index Terms--Multihop network, outage probability, routing, transmit energy.

Raptor codes have been standardized as application layer forward error correction (FEC) codes for Multimedia Broadcast and Multicast Services (MBMS) and Digital Video Broadcast (DVB) due to their extraordinary advanced FEC protection and performance. Raptor codes are known to have characteristics very close to ideal and provide a wide range of operating flexibility and efficiency unmatched by other codes, and in particular they are an excellent implementation of fountain codes. Until now, investigations of the application of Raptor codes to UMTS and EPGRS have used an overall system model that does not accurately model the physical channel and user mobility, simplistically assuming independent random packet losses at the application layer. We investigate MBMS in UMTS in a much more realistic and complete simulation environment by considering advanced and complete channel models that simulate the physical channel and user mobility in a cellular network. We use this realisitic simulation environment to determine optimal system parameters under different mobility models, with different bearer parameters, and without and with selective combining. More specifically, we investigate joint settings of the Raptor code rate, the Turbo code rate, transmission power, etc., to find settings which provide reliable download delivery of files using minimal transmission energy. One of our main results is that optimal system-wide operating points use low transmission power and a modest amount of Turbo coding that results in relatively large radio packet loss rates that is compensated for by using a substantial amount of Raptor coding. These optimal operating points use far less transmission energy for download delivery of files than possible operating points without Raptor. Index Terms--Application layer FEC, code rate, cross-layer optimization, FEC, forward error correction, fountain codes, MBMS, Raptor code, reliable multicast transmission, UMTS.

Several novel techniques are developed for the evolution of the CDMA2000 next generation data optimized 1x evolution-data only (EV-DO) system, the EV-DO Revision C system. Design objectives, framework solutions and key technologies of EV-DO Revision C system, a high-tech wireless technology with high spectral efficiencies for enhanced services, are discussed.

Cellular digital packet data (CDPD) provides a sleep-mode operation for power conservation in mobile end systems (M-ESs). We perform a theoretical analysis of sleep-mode operation for CDPD. Sleep-mode operation is modeled as an [M.sup.x]/G/1/L queueing system with an attention span and multiple vacations with an exceptional first vacation. The steady-state probabilities of the queueing system, the frame loss probability, the expected frame waiting time, and the percentage of time in the sleep period are derived. Sleep-mode performance is evaluated for varying packet arrival rate, buffer length, and timers' values using the queueing model. Sleep mode in an M-ES occurs when the packet arrival rate for the M-ES is low. When the M-ES is in sleep mode, the expected frame waiting time depends on T204 value. To keep the frame loss probability low for M-ES in sleep mode, the mobile data intermediate system buffer should be sufficiently large. Sleep mode can efficiently reduce power consumption by selecting a low value for timer T203 and a high value for timer T204. Index Terms--Cellular digital packet data (CDPD), inactivity timer, power conservation, queueing model, sleep mode, temporary equipment identifier (TEI) notification timer.

Dynamic rate adaptation for uplink data transmission in a cellular multidimensional multicode (MDMC) direct-sequence code-division multiple-access packet data network is modeled and analyzed in this paper. An analytical framework is developed to evaluate the performances of radio link level dynamic rate adaptation schemes under multipath fading and log-normal shadowing. The radio link level throughput under optimal dynamic rate adaptation (having exponential computational complexity) and different heuristic-based suboptimal rate adaptation schemes can be assessed under the presented analytical framework. The performance of MDMC signaling is compared with that of the single-code variable spreading factor (VSF) signaling. To this end, based on an equilibrium point analysis of the system in steady-state, a base station-assisted and mobile-controlled dynamic rate adaptation scheme is presented. Index Terms--Base station (BS)-assisted mobile-controlled algorithm, dynamic rate adaptation, joint multicell rate adaptation, multidimensional multicode (MDMC) signaling.

Cellular Digital Packet Data (CDPD) offers mobile users access to a low-cost, ubiquitous, wireless data network. CDPD can be overlaid on existing AMPS analog cellular systems and share their infrastructure equipment on a non-interfering basis. To prevent interference with the voice activities, CDPD performs forced hop to a channel stream when a voice request is about to use the RF channel occupied by that channel stream. In addition, several timers and system parameters are defined in CDPD to ensure that the normal AMPS activities are not affected by CDPD. This article investigates how the channel selection algorithms, the timers and other parameters affect the performance of AMPS/CDPD systems. Specifically, we study the trade-off between mean CDPD channel holding time and voice incompletion probability. Our study indicates that if AMPS exercises the most-idle channel selection algorithm and CDPD exercises the least-idle channel selection algorithm, then the largest mean CDPD channel holding time is expected. On the other hand, if AMPS exercises the least-idle channel selection algorithm, then the smallest voice incompletion probability is expected. [ABSTRACT FROM AUTHOR]

With the emergence of a variety of mobile data services with variable coverage, bandwidth, and handoff strategies, and the need for mobile terminals to roam among these networks, handoff in hybrid data networks has attracted tremendous attention. This article presents an overview of issues related to handoff with particular emphasis on hybrid mobile data networks. Issues are logically divided into architectural and handoff decision time algorithms. The handoff architectures in high-speed local coverage IEEE 802.11 wireless LANs, and low-speed wide area coverage CDPD and GPRS mobile data networks are described and compared. A survey of traditional algorithms and an example of an advanced algorithm using neural networks for PTO decision time in homogeneous networks are presented. The HO architectural issues related to hybrid networks are discussed through an example of a hybrid network that employs GPRS and IEEE 802.11. Five architectures for the example hybrid network, based on emulation of GPRS entities within the WLAN, mobile IP, a virtual access point, and a mobility gateway (proxy), are described and compared. The mobility gateway and mobile IP approaches are selected for more detailed discussion. The differences in applying a complex algorithm for HO decision time in a homogeneous and a hybrid network are shown through an example [ABSTRACT FROM PUBLISHER]

Byline: M. Ostrowski (1) Keywords: wireless; microcell; packed; data; CDPD Abstract: Two categories of commercial wireless packet services exist today -- a standalone system where the entire bandwidth is dedicated to the transmission of data packets (e.g. ARDIS, Mobitex), and an overlay system, where the unused channels of an existing cellular phone system are used (e.g. CDPD, GPRS). This paper examines the performance of the overlay service in a high density Manhattan street grid microcell. This type of cell is common in central urban areas. A simple analytical model is derived to describe the channel occupancy distribution in the microcell. The model is used to examine the performance of CDPD, a connectionless data service operating over a cellular system. Throughput and latency are evaluated under the two existing channel assignment schemes currently in use. A new assignment scheme is proposed, and is found to give better performance with minimal changes to the CDPD specification. Author Affiliation: (1) Centre for Telecommunications and Information Networking, University of Adelaide, USA Article History: Registration Date: 27/09/2004

Cellular digital packet data (CDPD) is a mobile packet data technology developed to operate on the spectrum assigned to a telephone cellular network. Since it operates on non-dedicated RF channels, it is subject to channel hopping and its performance is affected by the traffic profile of the underlying telephone system. We develop formulas expressing the normalized forward channel capacity in terms of telephone traffic conditions and channel hopping parameters. We show that forward capacity is very near to maximum for telephone network utilization less than one, while it degrades rapidly thereafter. Moreover, we develop an expression for the average hopping rate and we demonstrate the sensitivity of capacity with the number of RF channels [ABSTRACT FROM PUBLISHER]

Cellular digital packet data (CDPD) utilizes sleep mode mechanism to conserve the power of mobile end systems (M-ESs). A timer called T203 determines how quick an M-ES enters the sleep mode, and another timer called T204 determines how often the M-ES wakes up. A large T204 value and a small T203 value can effectively reduce the power consumption at the cost of degrading the frame transmission performance, i.e., more lost frames, longer frame waiting times, and larger waiting variance. When the power consumption budget is determined in a CDPD system design, our study provides guidelines to determine the timer values as well as the buffer size to optimize the frame transmission performance [ABSTRACT FROM PUBLISHER]