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Global Telecommunications Conference Workshops, 2004. GlobeCom Workshops 2004. IEEE

Date 29 Nov.-3 Dec. 2004

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Displaying Results 1 - 25 of 105
  • An energy-efficiency MAC protocol in multi-rate and multi-range infrastructure wireless networks

    Publication Year: 2004 , Page(s): 44 - 49
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (563 KB) |  | HTML iconHTML  

    In this paper, we study an energy-efficiency relay-based protocol that can select a proper PHY mode and a transmission power level, and analyze its energy-efficiency, defined as the number of data bits transmitted per unit energy. Evaluation results show that this protocol and its degraded version can provide significant improvements on the energy-efficiency and remarkably enhance the overall system performance. View full abstract»

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  • Energy aware routing protocol (EARP) for ad-hoc wireless sensor networks

    Publication Year: 2004 , Page(s): 419 - 427
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (546 KB) |  | HTML iconHTML  

    Wireless ad-hoc sensor networks differ from wireless ad-hoc networks from the following perspectives: greater energy constraint, light weight routing protocols, and flexible communication patterns. This paper proposes an energy aware routing protocol (EARP) and presents an analysis for energy consumption in various phases of route discovery and maintenance. Based on the energy consumption associated with route request processing, EARP advocates the minimization of route requests by allocating dynamic route expiry times. This paper introduces a unique mechanism for estimation of route expiry time based on probability of route validity (Proute-valid), which is a function of time, number of hops and mobility parameters. In contrast to AODV, EARP reduces the repeated flooding of route requests by maintaining valid routes for durations longer than ten seconds as fixed by AODV. View full abstract»

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  • Quality of service provisioning in wireless LAN/UMTS integrated systems using analytic hierarchy process and Grey relational analysis

    Publication Year: 2004 , Page(s): 220 - 224
    Cited by:  Papers (15)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (630 KB) |  | HTML iconHTML  

    3G cellular systems provide users with high mobility with low bandwidth. Wireless LAN is adopted as a complementary' service to support high bandwidth in some hot spots. In this paper, we develop a network selection mechanism for the integrated 3G/wireless LAN networks. The proposed network selection combines analytic hierarchy process and Grey relational analysis. The selection procedures are presented and evaluated in four simulation cases. The results show that the proposed scheme can effectively choose the optimum network for users through balancing between objective network conditions and subjective user requirements. View full abstract»

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  • Admission control in IEEE 802.11 networks

    Publication Year: 2004 , Page(s): 258 - 265
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (532 KB) |  | HTML iconHTML  

    The IEEE 802.11e standard is intended to support the applications with QoS requirements. Such support is achieved by using differentiated categories for medium access. When the number of active stations is high, collision rate increases, affecting goodput and delay. In this paper, the effectiveness of two mechanisms for measurement-based admission control in 802.11e networks are evaluated. View full abstract»

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  • Performance evaluation of rate control and QoS capabilities of BRAS

    Publication Year: 2004 , Page(s): 293 - 301
    Cited by:  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (777 KB) |  | HTML iconHTML  

    This paper reports the initial results of OPNET simulation modeling of DSL Forum TR.59 and WT92 traffic management capabilities required in BRAS to deliver end-to-end IP QoS over an existing DSL access network and emerging architectures. TR.59 extends the role of the BRAS to include congestion management of the access network, provide IP QoS per user downstream and rate limiting upstream. The objective of the simulations and the results reported here is to demonstrate the feasibility of such an extension and to evaluate the efficiency of traffic management mechanisms in enabling the new required capabilities in BRAS. View full abstract»

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  • A dynamic pricing model for data services in GPRS networks

    Publication Year: 2004 , Page(s): 453 - 458
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (598 KB) |  | HTML iconHTML  

    GPRS data services are subject to severe performance degradation due to limited network resources. The technical approaches taken to alleviate the problem are not sufficient to encounter a complete range of incoming scenarios. In this paper, we define and study analytically a performance model for GPRS data services that takes into account prices that change dynamically, depending on the congestion in the system. The model is based on a Markov modulated Poisson process (MMPP), where the arrival rates are affected by a demand function. Performance metrics are also calculated. We believe that the proposed model captures the effect of dynamic pricing on the performance of GPRS data services in a realistic manner. View full abstract»

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  • GhostShare - reliable and anonymous P2P video distribution

    Publication Year: 2004 , Page(s): 200 - 210
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (887 KB) |  | HTML iconHTML  

    P2P networks have emerged as a powerful multimedia content distribution mechanism. However, the widespread deployment of P2P networks are hindered by several issues, especially ones that influence end-user satisfaction, including privacy protection. In this paper, we propose GhostShare, a P2P network built on the pastry substrate, to distribute video content. The primary design goals of GhostShare are anonymity and load balancing for participating peers. We present simulation results that prove the effectiveness of GhostShare's load balancing mechanism and provide an analysis of the anonymity scheme. View full abstract»

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  • A GMPLS-controlled optical testbed for distributed storage services

    Publication Year: 2004 , Page(s): 363 - 368
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (674 KB) |  | HTML iconHTML  

    As services and applications become more integrated with the underlying network, it is desirable to increase the degree of coupling between end-to-end services and the provisioning, monitoring and recovery mechanisms of optical communications channels. In this paper, we describe an experimental demonstration of GMPLS control of an optical network for wide-area distributed storage services. The dynamic nature of GMPLS control enable scheduled backup of distributed storage over high-speed optical lightpaths provisioned on demand. Inter-working issues between application layer and transport layer are discussed, highlighting key design and implementation choices for connectivity discovery, signaling, optical hardware control and service resilience. View full abstract»

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  • Optimal dynamic periodic location update for UMTS mobile networks - a simulation approach

    Publication Year: 2004 , Page(s): 225 - 229
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (595 KB) |  | HTML iconHTML  

    Location management is essential for delivering services to mobile stations (MSs) in mobile networks. In 3GPP technical specifications for the circuit-switched domain of Universal Mobile Telecommunications System, both normal location update and periodic location update (PLAU) are adopted to track locations of MSs. PLAU is also used for detecting detachment of an MS from the network. In this paper, we analyze the cost of location management under the presence of abnormal detachments. Based on our cost analysis, we propose a simulation approach to find the optimal parameter to minimize the cost for the dynamic PLAU. A gradient descent algorithm is also implemented to find the optimal parameter for a different cost function. Results show that the cost is significantly deducted with the proposed optimal approach. Another contribution is that we show how to solve an optimization problem through a simulation approach. View full abstract»

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  • A window-based object allocation and replication algorithm for real-time distributed database systems in mobile computing environment

    Publication Year: 2004 , Page(s): 491 - 499
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (601 KB) |  | HTML iconHTML  

    A real-time distributed database system (RTDDBS) must maintain the consistency constraints of objects and must also guarantee the deadline imposed by each arriving request. Servicing these requests may incur I/O costs, control-message transferring costs or data-message transferring costs. In this paper, we consider our system in the mobile computing environment, where the link bandwidth is very limited and hence the transfer of data-messages and control-messages over the wireless network incurs very high cost when compared to I/O cost. Thus, we present a mathematical model that considers the communication costs (control-message/data-message transferring cost) associated with the servicing of a request. Using this cost model, our objective is to service the arriving requests on or before their respective deadline periods and minimize the total communication cost. To this end, we design an adaptive object allocation and replication algorithm, referred to as real-time distributed dynamic window mechanism (RDDWM), that adapts to the random patterns of read-write requests. Using competitive analysis, we study the performance of RDDWM algorithm under two extreme conditions. View full abstract»

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  • Improving H.264 real-time streaming in MANETs through adaptive multipath routing techniques

    Publication Year: 2004 , Page(s): 433 - 441
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (562 KB) |  | HTML iconHTML  

    One of the main problems associated with MANETs is that mobility and the associated route discovery and maintenance procedures of reactive routing protocols cause interruptions on real-time video streams. Some of these interruptions are too large to be concealed using any sort of video technology, resulting in communications breaks unpleasant for the final end user. We present a solution for enhanced video transmission that increases route stability by using an improved route discovery process based on the DSR routing protocol, along with traffic splitting algorithms and a preventive route discovery mechanism. We also present a tuning methodology for an H.264 video codec in order to obtain optimal interaction with the underlying mechanisms proposed. Combining our proposals, we achieve up to 97% less interruptions on communication with high mobility, and over 1.2 dB of improvements in terms of video distortion. View full abstract»

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  • A comparison of in-band and out-of-band transport options for signaling

    Publication Year: 2004 , Page(s): 345 - 351
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (611 KB) |  | HTML iconHTML  

    Signaling protocols for GMPLS networks have been standardized and are now being implemented. Most switch vendors allow for signaling messages to be carried over in-band signaling channels as well as through out-of-band networks. In this paper, we compare these two signaling transport options. In carrying out this analysis, we allow for both software-implemented signaling protocol processors, as is common in most off-the-shelf switches today, as well as hardware-accelerated signaling protocol engines. Our research project on hardware-accelerated signaling is in support of a service concept in which dynamically provisioned high-speed end-to-end circuits are used for single file transfers. In this application, signaling message loads will be extremely high since call holding times will be short. For such a usage, we need a signaling transport solution that minimizes message transfer times. Therefore this question of in-band versus out-of-band signaling transport is relevant to our research. Our analysis shows that with hardware-accelerated signaling engines, in-band signaling is the better option, while in a network with only software signaling processors, the out-of-band solution is better. View full abstract»

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  • Topology-transparent node activation scheduling schemes for multihop TDMA ad hoc networks

    Publication Year: 2004 , Page(s): 68 - 73
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (585 KB) |  | HTML iconHTML  

    In this paper, we study topology-transparent node activation transmission scheduling protocols for multihop TDMA ad hoc networks. We focus on quality-of-service (QoS) provisioning for each node, particularly when node mobility is considered. A framework for topology-transparent node activation scheduling based on theory of block designs is proposed. The proposed framework guarantees conflict-free transmission slots for each node in each frame by mathematical properties of block designs. Based on two mapping methods, called mapping I and mapping II, the proposed framework can be categorized into two types. With the proposed framework, we study and evaluate some series of block constructions. We then propose several topology-transparent scheduling algorithms based on the results derived. The proposed schemes maximize the minimum system throughput. Numerical results show that the proposed algorithms can outperform existing algorithms in achieving a higher minimum system throughput. View full abstract»

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  • Object-oriented modeling and simulation of optical burst switching networks

    Publication Year: 2004 , Page(s): 288 - 292
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1558 KB) |  | HTML iconHTML  

    Optical burst switching (OBS) is becoming an interesting technology for the optical Internet, since it does not need optical buffers like optical packet switching (OPS), and is capable of a better performance than optical circuit switching (OCS). Although OBS has been recently an object of intense research, it still raises a number of important questions. Due to the high costs of an OBS network infrastructure, simulators are a good choice for predicting the behavior of this kind of networks. In this paper, we describe the proposal, implementation and validation of a simulator for OBS networks. The simulator, named OBSim, mimics the behavior of OBS networks in an object-oriented approach. View full abstract»

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  • A grid oriented lightpath provisioning system

    Publication Year: 2004 , Page(s): 395 - 399
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (578 KB) |  | HTML iconHTML  

    Multi-domain resource sharing is the fundamental feature of computing and data grid applications. In this paper, we address the issue of multi-domain optical network resource sharing and present a network management system designed for end-to-end lightpath provisioning across multiple independently managed domains. Our network management system, called user-controlled lightpath provisioning (UCLP) system, is based on the grid services concept and built on the Jini and JavaSpaces technologies. The UCLP system provides a traffic engineering approach to control network infrastructure for computing and data grid applications. View full abstract»

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  • A priority-based QoS routing protocol with zone reservation and adaptive call blocking for mobile ad hoc networks with directional antenna

    Publication Year: 2004 , Page(s): 50 - 55
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (675 KB) |  | HTML iconHTML  

    Existing priority-based QoS routing protocols in ad hoc wireless networks did not consider the effect of mutual interference between routes in wireless medium during routing. We have investigated the effect of mutual interference on the routing performance in wireless environment and explored the advantage of using zone-disjoint routes to avoid mutual interference and to improve the network performance. In this paper, a priority based QoS routing scheme is proposed that uses the notion of zone-disjoint routes. Our protocol avoids the contention between high and low priority routes by reserving high priority zone of communication. Low priority flows tries to avoid this zone by selecting the routes that is maximally zone-disjoint with respect to the high priority reserved zone and consequently allows a contention-free transmission of high priority traffic in that reserved zone. If, under some unavoidable situations, a low priority flow has to go through high priority reserved zone causing interference, then it blocks itself temporarily to allow contention-free transmission of high priority flows and later may resume the blocked communication if possible. We have evaluated the effectiveness of our proposed protocol on QualNet network simulator. View full abstract»

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  • itmBench: generalized API for Internet traffic managers

    Publication Year: 2004 , Page(s): 306 - 311
    Cited by:  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (523 KB) |  | HTML iconHTML  

    Internet traffic managers (ITMs) are special machines placed at strategic places in the Internet. itmBench is an interface that allows users (e.g. network managers, service providers, or experimental researchers) to register different traffic control functionalities to run on one ITM or an overlay of ITMs. Thus itmBench offers a tool that is extensible and powerful yet easy to maintain. ITM traffic control applications could be developed either using a kernel API so they run in kernel space, or using a user-space API so they run in user space. We demonstrate the flexibility of itmBench by showing the implementation of a kernel module that provides a differentiated network service. Due to space limitations, we refer the reader to Gali Diamant et al. (December 16, 2003) for a user-space module that provides an overlay routing service. Our itmBench Linux-based prototype is free software and can be obtained from http: //www.cs.bu.edu/groups/itm/. View full abstract»

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  • An efficient error resilient technique for applications of one-way video using transcoding and analysis by synthesis

    Publication Year: 2004 , Page(s): 428 - 432
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (646 KB) |  | HTML iconHTML  

    In this paper, we describe an efficient error resilient technique for one-way video transmitted over lossy packet networks. In one-way video applications, video sequences are pre-encoded off-line to be stored in a server without any information on transmission error. Therefore, video encoding algorithm, should be designed without any error resilience or with a hypothetical PLR (packet loss rates) for a certain degree of robustness to be transmitted over error prone environments. However, the PLRs differ according to the various kinds of networks, and even the time varying in a network. A dynamic update of video stream for the adaptive enhancement of error resilience was introduced with a transcoding technique to deal with variable PLRs. An error-sensitivity of each pixel is defined and computed in the transcoder, according to the PLR from network feedback and the effects of error propagations. The error-sensitivity was monitored by the transcoder to modify the video stream for the enhancement of error resilience. The basic error resilience scheme is blocking spatial and temporal error propagation. An analysis by synthesis scheme is introduced for 1) the estimate of accurate distortion at the decoder by exact simulation of error concealment, 2) motion vector re-estimation for blocking temporal error propagation. The optimal mode of each macroblock was decided in the rate-distortion (R-D) framework of the receiver at the given PLR and macroblock location. The performance of the proposed algorithm was evaluated with MPEG-2 video stream over lossy packet network scenario. Experimental results show that the proposed error resilience algorithm outperformed the MPEG-2 TM5 and boundary motion compensated error concealment scheme. It was also shown that the proposed algorithm makes stored one-way video stream applicable for any kinds of error prone networks with variable error rates. View full abstract»

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  • A reverse link power control algorithm based on game theory for multi-cell wireless data networks

    Publication Year: 2004 , Page(s): 459 - 468
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (696 KB) |  | HTML iconHTML  

    We propose a new decentralized power control algorithm for multi-cell wireless data networks that can fully utilize and equally assign radio resources to all mobile stations (MSs). Our approach employs game theory as its basis with a utility function and pricing, but uses the network (base station) to assist mobile stations in performing power control. This is similar to a leader-followers strategy used in the literature of game theory. As a result, the proposed algorithm is implemented in the form of closed loop power control. This proposed power control scheme can maximize the throughput of each MS and can fully utilize the amount of radio resources allowed in a cell. View full abstract»

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  • A video frame dropping mechanism based on audio perception

    Publication Year: 2004 , Page(s): 211 - 216
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (578 KB) |  | HTML iconHTML  

    Video streaming applications are more and more present in our life, but despite the advances of network technologies, several users experience QoS problems. This is mainly due to the high bandwidth requirements of these applications that contrasts with the network bandwidth limitation. To mitigate these QoS problems, video frame dropping mechanisms are often used for adapting the video stream to the network conditions. The selection of the video frames to drop is done considering the perceived quality of the video play out; audio perception is not considered in the selection process. In this paper, we show that by taking into account only the video play out quality, audio problems arise very frequently. Hence, we propose a video frame dropping mechanism that takes into consideration the perceived quality of both audio and video play out. A comparison with other video frame dropping techniques is carried out and experimental results show that, although the video play out quality is similar, the audio play out quality is completely different. Our mechanism slightly affects the audio quality, while other techniques strongly affect it. Therefore, by using our mechanism, benefits are remarkable. View full abstract»

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  • Impacts of GMPLS on topology design and protection planning of survivable IP-over-optical networks

    Publication Year: 2004 , Page(s): 352 - 356
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (624 KB) |  | HTML iconHTML  

    The convergence of IP and optical networks through the GMPLS common control plane motivates a new paradigm of integrated network management. In this paper, we study how the new synergy between the IP and optical layers influence the decision on topology design and protection planning of survivable IP-over-optical networks. We discovered a new guideline which indicates that existing balanced and sparse networks could benefit the most from the migration from the single-layer management to the GMPLS-based multi-layer management. View full abstract»

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  • Congestion control and service differentiation in multihop wireless networks

    Publication Year: 2004 , Page(s): 62 - 67
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (617 KB) |  | HTML iconHTML  

    This paper describes a practical algorithm for congestion control and service differentiation in multihop wireless networks using CSMA/CA type MAC protocol. The algorithm is designed by taking into account the implementation issues of distributed contention based transmission protocols without a central controller. The proposed algorithm computes a weighted load metric related to the queue status of the nodes to provide a distributed and stateless traffic control mechanism. Service differentiation is achieved through intranode and internode scheduling. Fairness is provided in terms of fair sharing both channels and next hops (Le. forwarding nodes). Performance evaluation in both laboratory and live networks is used to optimize the algorithm. View full abstract»

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  • A novel signaling approach to encompass physical impairments in GMPLS networks

    Publication Year: 2004 , Page(s): 369 - 373
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (592 KB) |  | HTML iconHTML  

    Next generation networks are expected to be characterized by domains of transparency in which a GMPLS common control plane is adopted to manage both the IP layer and the optical transport layer. Within domains of transparency the end-to-end lightpath signal quality has to be guaranteed. However, currently, GMPLS does not take into account the evaluation of physical impairments. Thus just limited size domains of transparency are practically achievable. In this study a novel approach to dynamically estimate the end-to-end signal quality is proposed. The method is based on the introduction, into current GMPLS signaling and management protocols, of extensions which encompass the physical parameters that characterize the optical transport layer. The proposed approach allows to detect whether lightpaths cannot be set up because of accumulated linear physical impairments during their signaling phase. Numerical results show that the lightpath blocking probability due to physical impairments decreases by implementing suitable routing policies, such as multiple attempts. Thus few very impaired links can be introduced into large domains of transparency without affecting the overall network performance. An experimental implementation based on PXC and IP routers is also presented to validate the feasibility of the proposed approach. View full abstract»

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  • Online ring structure adaptation for mobile wireless computing

    Publication Year: 2004 , Page(s): 500 - 506
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (568 KB) |  | HTML iconHTML  

    In a mobile ad hoc (multi-hop) wireless network, the logical structure of a ring is likely to become volatile or expensive to maintain over time due to changeable network topology. Additional adverse effects take place when a node joins or leaves the computation in the presence of mobility. This paper presents a protocol that adapts a ring among mobile nodes to the network dynamics to reflect overall communication efficiency. This is achieved by modifying the ring structure in a localized, mutual exclusive fashion, thereby allowing for concurrent segment-wise modifications to proceed. Remarkably our proposal operates without global knowledge of the logical structure and can be embodied as an underlying protocol stratum that supports transparent deployments of conventional algorithms in mobile environment. Subsequent to correctness proof, simulation results show that our proposal is promising in several regards. View full abstract»

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  • A simplified generic optimum power control scheme for CDMA cellular systems

    Publication Year: 2004 , Page(s): 414 - 418
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (684 KB) |  | HTML iconHTML  

    Power control is of great importance in reducing cochannel interference and increasing the capacity of mobile telecommunications systems. The aim of optimum power control procedure is to achieve a maximum carrier-to-interference ratios (CIR) in all active communication links (i.e. CIR balancing). Optimum power control with CIR balancing has been widely studied for frequency-division/time-division multiple access (FDMA/TDMA) cellular systems. In these systems, the CIR-balanced optimum power control was transformed to an eigenvalue problem using link-gain matrix. The same method was proposed to CDMA systems. However, the size of the link-gain matrix is proportional to the square of the number of communication links in the system. Thus, the computation of the eigenvalue may be infeasible in CDMA systems with high load. Moreover, optimum power control has never been studied in crossed slots where some mobiles are active in downlink and other in uplink. A simplified optimum power control scheme has been proposed to reduce the link-gain matrix only in the forward link. In this paper, we introduce a simplified generic optimum power control scheme for uplink, downlink and crossed slots. This scheme is based on a link-gain matrix whose size is proportional to the square of the number of cells. Simulation results have justified that the proposed scheme achieves the same upper bound of CIR as the complex scheme. View full abstract»

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