Quality of service and channel-aware packet bundling for capacity improvement in cellular networks

Title from PDF of title page, viewed on May 26, 2011VitaIncludes bibliographical references (p. 76-84)Thesis (Ph.D.)--School of Computing and Engineering. University of Missouri--Kansas City, 2011We study the problem of multiple packet bundling to improve spectral efficiency in cellular networks. The packet size of real-time data, such as VoIP, is often very small. However, the common use of time division multiplexing limits the number of VoIP users supported, because a packet has to wait until it receives a time slot, and if only one small VoIP packet is placed in a time slot, capacity is wasted. Packet bundling can alleviate such a problem by sharing a time slot among multiple users. A recent revision of cdma2000 1xEV-DO introduced the concept of the multi-user packet (MUP) in the downlink to overcome limitations on the number of time slots. However, the efficacy of packet bundling is not well understood, particularly in the presence of time varying channels. We propose a novel QoS and channel-aware packet bundling algorithm that takes advantage of adaptive modulation and coding. We show that optimal algorithms are NP complete and recommend heuristic approaches. We also show that channel utilization can be significantly increased by slightly delaying some real-time packets within their QoS requirements while bundling those packets with like channel conditions. We validate our study through extensive OPNET simulations with a complete EV-DO implementation.Introduction -- Related work -- Background on wireless systems -- Multiple packet bundling -- Evaluation -- Conclusion

GAME THEORETIC APPROACH TO RADIO RESOURCE MANAGEMENT ON THE REVERSE LINK FOR MULTI-RATE CDMA WIRELESS DATA NETWORKS

This work deals with efficient power and rate assignment to mobile stations (MSs) involved in bursty data transmission in cellular CDMA networks. Power control in the current CDMA standards is based on a fixed target signal quality called signal to interference ratio (SIR). The target SIR represents a predefined frame error rate (FER). This approach is inefficient for data-MSs because a fixed target SIR can limit the MS's throughput. Power control should thus provide dynamic target SIRs instead of a fixed target SIR. In the research literature, the power control problem has been modeled using game theory. A limitation of the current literature is that in order to implement the algorithms, each MS needs to know information such as path gains and transmission rates of all other MSs. Fast rate control schemes in the evolving cellular data systems such as cdma2000-1x-EV assign transmission rates to MSs using a probabilistic approach. The limitation here is that the radio resources can be either under or over-utilized. Further, all MSs are not assigned the same rates. In the schemes proposed in the literature, only few MSs, which have the best channel conditions, obtain all radio resources. In this dissertation, we address the power control issue by moving the computation of the Nash equilibrium from each MS to the base station (BS). We also propose equal radio resource allocation for all MSs under the constraint that only the maximum allowable radio resources are used in a cell. This dissertation addresses the problem of how to efficiently assign power and rate to MSs based on dynamic target SIRs for bursty transmissions. The proposed schemes in this work maximize the throughput of each data-MS while still providing equal allocation of radio resources to all MSs and achieving full radio resource utilization in each cell. The proposed schemes result in power and rate control algorithms that however require some assistance from the BS. The performance evaluation and comparisons with cdma2000-1x-Evolution Data Only (1x-EV-DO) show that the proposed schemes can provide better effective rates (rates after error) than the existing schemes

Demand-Based Wireless Network Design by Test Point Reduction

The problem of locating the minimum number of Base Stations (BSs) to provide sufficient signal coverage and data rate capacity is often formulated in manner that results in a mixed-integer NP-Hard (Non-deterministic Polynomial-time Hard) problem. Solving a large size NP-Hard problem is time-prohibitive because the search space always increases exponentially, in this case as a function of the number of BSs. This research presents a method to generate a set of Test Points (TPs) for BS locations, which always includes optimal solution(s). A sweep and merge algorithm then reduces the number of TPs, while maintaining the optimal solution. The coverage solution is computed by applying the minimum branching algorithm, which is similar to the branch and bound search. Data Rate demand is assigned to BSs in such a way to maximize the total network capacity. An algorithm based on Tabu Search to place additional BSs is developed to place additional BSs, in cases when the coverage solution can not meet the capacity requirement. Results show that the design algorithm efficiently searches the space and converges to the optimal solution in a computationally efficient manner. Using the demand nodes to represent traffic, network design with the TP reduction algorithm supports both voice and data users

SCHEDULING IN PACKET SWITCHED CELLULAR WIRELESS SYSTEMS

In cellular wireless networks where users have independent fading channels, throughput for delay tolerant applications has been greatly increased on the downlink by using opportunistic schedulers at the base station. These schedulers exploit the multiuser diversity inherent in cellular systems. An interesting question is how opportunistic schedulers will provide Quality of Service(QoS) guarantees for a mix of data traffic and traffic from delay-sensitive multimedia applications. In the first part of this dissertation, we completely characterize the scheduled rate, delay and packet service times experienced by mobile users in a packet switched cellular wireless system in terms of a configurable base station scheduler metric. The metric used has a general form, combining an estimate of a mobile user's channel quality with the scheduling delay experienced by the user. In addition to quantifying the scheduler performance, our analysis highlights the inherent trade-off between system throughput and the delay experienced by mobile users with opportunistic scheduling. We also use this analysis to study the effect of prioritized voice users on data users in a cellular wireless system with delay constrained opportunistic scheduling. Our statistical analysis of the forward link is validated by extensive simulations of a system architecture based on the CDMA 1xEV-DO system. The increase in data traffic from mobiles to the base station has led to a growing interest in a scheduled reverse link in the 1xEV-DO system. We address the reverse link scheduling problem in a multi-cell scenario with interference constraints both within and outside the cell. This approach leads to a co-operative scheduling algorithm where each base station in a cellular network maximizes the sum of mobile data transmission rates subject to linear constraints on (1) the maximum received power for individual mobiles(2) the total interference caused by scheduled mobiles to (a) traffic and control channels of other mobiles within the cell and (b) mobiles in neighboring cells. Simulations of the reverse link structure based on the 1xEV-D0 system highlight the distinct advantages of this algorithm in ensuring predictable inter-cell interference and higher aggregate cell throughputs

Technology Forecasting for Wireless Communication

Wireless communications technologies have undergone rapid changes over the last 30 years from analog approaches to digital-based systems. These technologies have improved on many fronts including bandwidth, range, and power requirements. Development of new telecommunications technologies is critical. It requires many years of efforts. In order to be competitive, it is critical to establish a roadmap of future technologies. This paper presents a framework to characterize, assess and forecast the wireless communication technologies. A DEA-based methodology was used for predicting the state-of-the-art in future wireless communications technologies

A General Framework for Analyzing, Characterizing, and Implementing Spectrally Modulated, Spectrally Encoded Signals

Fourth generation (4G) communications will support many capabilities while providing universal, high speed access. One potential enabler for these capabilities is software defined radio (SDR). When controlled by cognitive radio (CR) principles, the required waveform diversity is achieved via a synergistic union called CR-based SDR. Research is rapidly progressing in SDR hardware and software venues, but current CR-based SDR research lacks the theoretical foundation and analytic framework to permit efficient implementation. This limitation is addressed here by introducing a general framework for analyzing, characterizing, and implementing spectrally modulated, spectrally encoded (SMSE) signals within CR-based SDR architectures. Given orthogonal frequency division multiplexing (OFDM) is a 4G candidate signal, OFDM-based signals are collectively classified as SMSE since modulation and encoding are spectrally applied. The proposed framework provides analytic commonality and unification of SMSE signals. Applicability is first shown for candidate 4G signals, and resultant analytic expressions agree with published results. Implementability is then demonstrated in multiple coexistence scenarios via modeling and simulation to reinforce practical utility

Identification of Technologies for Provision of Future Aeronautical Communications

This report describes the process, findings, and recommendations of the second of three phases of the Future Communications Study (FCS) technology investigation conducted by NASA Glenn Research Center and ITT Advanced Engineering & Sciences Division for the Federal Aviation Administration (FAA). The FCS is a collaborative research effort between the FAA and Eurocontrol to address frequency congestion and spectrum depletion for safety critical airground communications. The goal of the technology investigation is to identify technologies that can support the longterm aeronautical mobile communication operating concept. A derived set of evaluation criteria traceable to the operating concept document is presented. An adaptation of the analytical hierarchy process is described and recommended for selecting candidates for detailed evaluation. Evaluations of a subset of technologies brought forward from the prescreening process are provided. Five of those are identified as candidates with the highest potential for continental airspace solutions in L-band (P-34, W-CDMA, LDL, B-VHF, and E-TDMA). Additional technologies are identified as best performers in the unique environments of remote/oceanic airspace in the satellite bands (Inmarsat SBB and a custom satellite solution) and the airport flight domain in C-band (802.16e). Details of the evaluation criteria, channel models, and the technology evaluations are provided in appendixes

Technology Assessment for the Future Aeronautical Communications System

To address emerging saturation in the VHF aeronautical bands allocated internationally for air traffic management communications, the International Civil Aviation Organization (ICAO) has requested development of a common global solution through its Aeronautical Communications Panel (ACP). In response, the Federal Aviation Administration (FAA) and Eurocontrol initiated a joint study, with the support of NASA and U.S. and European contractors, to provide major findings on alternatives and recommendations to the ICAO ACP Working Group C (WG-C). Under an FAA/Eurocontrol cooperative research and development agreement, ACP WG-C Action Plan 17 (AP-17), commonly referred to as the Future Communications Study (FCS), NASA Glenn Research Center is responsible for the investigation of potential communications technologies that support the long-term mobile communication operational concepts of the FCS. This report documents the results of the first phase of the technology assessment and recommendations referred to in the Technology Pre-Screening Task 3.1 of AP-17. The prescreening identifies potential technologies that are under development in the industry and provides an initial assessment against a harmonized set of evaluation criteria that address high level capabilities, projected maturity for the time frame for usage in aviation, and potential applicability to aviation. A wide variety of candidate technologies were evaluated from several communications service categories including: cellular telephony; IEEE-802.xx standards; public safety radio; satellite and over-the-horizon communications; custom narrowband VHF; custom wideband; and military communications