Interference-Mitigating Waveform Design for Next-Generation Wireless Systems

A brief historical perspective of the evolution of waveform designs employed in consecutive generations of wireless communications systems is provided, highlighting the range of often conflicting demands on the various waveform characteristics. As the culmination of recent advances in the field the underlying benefits of various Multiple Input Multiple Output (MIMO) schemes are highlighted and exemplified. As an integral part of the appropriate waveform design, cognizance is given to the particular choice of the duplexing scheme used for supporting full-duplex communications and it is demonstrated that Time Division Duplexing (TDD) is substantially outperformed by Frequency Division Duplexing (FDD), unless the TDD scheme is combined with further sophisticated scheduling, MIMOs and/or adaptive modulation/coding. It is also argued that the specific choice of the Direct-Sequence (DS) spreading codes invoked in DS-CDMA predetermines the properties of the system. It is demonstrated that a specifically designed family of spreading codes exhibits a so-called interference-free window (IFW) and hence the resultant system is capable of outperforming its standardised counterpart employing classic Orthogonal Variable Spreading Factor (OVSF) codes under realistic dispersive channel conditions, provided that the interfering multi-user and multipath components arrive within this IFW. This condition may be ensured with the aid of quasisynchronous adaptive timing advance control. However, a limitation of the system is that the number of spreading codes exhibiting a certain IFW is limited, although this problem may be mitigated with the aid of novel code design principles, employing a combination of several spreading sequences in the time-frequency and spatial-domain. The paper is concluded by quantifying the achievable user load of a UTRA-like TDD Code Division Multiple Access (CDMA) system employing Loosely Synchronized (LS) spreading codes exhibiting an IFW in comparison to that of its counterpart using OVSF codes. Both system's performance is enhanced using beamforming MIMOs

Bandwidth allocation for wireless multimedia systems.

Chen Chung-Shue.Thesis (M.Phil.)--Chinese University of Hong Kong, 2001.Includes bibliographical references (leaves 100-102).Abstracts in English and Chinese.Chapter 1. --- Introduction --- p.1Chapter 1.1 --- Evolution to 3G Mobile --- p.2Chapter 1.1.1 --- First Generation --- p.2Chapter 1.1.2 --- Second Generation --- p.3Chapter 1.1.3 --- Third Generation --- p.3Chapter 1.2 --- UTRA Framework --- p.5Chapter 1.2.1 --- FDD and TDD --- p.6Chapter 1.2.2 --- Channel Spreading --- p.6Chapter 1.2.3 --- OVSF Code Tree --- p.8Chapter 1.3 --- Cellular Concepts --- p.10Chapter 1.3.1 --- System Capacity --- p.10Chapter 1.3.2 --- Multiple Access --- p.11Chapter 1.3.3 --- Resource Management --- p.15Chapter 1.4 --- Organization of the Thesis --- p.16Chapter 2. --- Analysis on Multi-rate Operations --- p.18Chapter 2.1 --- Related Works in Multi-rate Operations --- p.18Chapter 2.1.1 --- Variable Spreading Factor --- p.19Chapter 2.1.2 --- Data Time-multiplexing --- p.20Chapter 2.1.3 --- Multi-carrier Transmission --- p.21Chapter 2.1.4 --- Hybrid TDMA/CDMA --- p.23Chapter 2.2 --- Problems in Multi-rate Operations --- p.24Chapter 2.2.1 --- Conventional CDMA --- p.24Chapter 2.2.2 --- Data Time-multiplexing --- p.25Chapter 2.2.3 --- MC-CDMA --- p.25Chapter 2.2.4 --- TD-CDMA --- p.27Chapter 2.3 --- Multi-user multi-rate Operations --- p.28Chapter 3. --- Bandwidth Allocation --- p.29Chapter 3.1 --- Most Regular Binary Sequence --- p.30Chapter 3.1.1 --- Properties of MRBS --- p.31Chapter 3.1.2 --- Construction of MRCS --- p.32Chapter 3.1.3 --- Zero-one Sequence under MRBS --- p.33Chapter 3.2 --- MRBS in TD-CDMA --- p.35Chapter 3.2.1 --- Time Slot Optimization --- p.36Chapter 3.2.2 --- Sequence Generator --- p.37Chapter 3.3 --- Most Regular Code Sequence --- p.38Chapter 3.3.1 --- Properties of MRCS --- p.38Chapter 3.2.2 --- Construction of MRCS --- p.41Chapter 3.3.3 --- Fraction-valued Sequence under MRCS --- p.42Chapter 3.3.4 --- LCC and UCC --- p.45Chapter 3.4 --- MRCS in WCDMA --- p.46Chapter 3.4.1 --- Spreading Factor Optimization --- p.46Chapter 3.4.2 --- Code Generator --- p.48Chapter 3.4.3 --- Uplink and Downlink --- p.50Chapter 4. --- Multi-access Control --- p.52Chapter 4.1 --- Conflict and Resolution --- p.53Chapter 4.1.1 --- Conflicts in MRBS and MRCS --- p.53Chapter 4.1.2 --- Resolution with Buffering --- p.55Chapter 4.2 --- MRBS Transmission Scheduling --- p.56Chapter 4.2.1 --- Slot Scheduling on MRBS --- p.56Chapter 4.2.2 --- Properties of Scheduling Algorithm --- p.59Chapter 4.2.3 --- Scheduled MRBS --- p.71Chapter 4.3 --- MRCS Transmission Scheduling --- p.73Chapter 4.3.1 --- Slot Scheduling on MRCS --- p.73Chapter 4.3.2 --- Properties of Scheduling Algorithm --- p.75Chapter 4.3.3 --- Scheduled MRBS --- p.76Chapter 4.4 --- Performance Evaluation --- p.78Chapter 4.4.1 --- Simulation on Algorithm --- p.78Chapter 4.4.2 --- Resource Utilization and Delay Bound --- p.79Chapter 4.4.3 --- Blocking Model and System Capacity --- p.80Chapter 4.4.4 --- Numerical Analysis --- p.86Chapter 5. --- Conclusions and Future works --- p.92Appendix A --- p.94Appendix B --- p.98Bibliography --- p.10

Reverse Link Analysis and Modeling of CDMA based Distributed Antenna Systems

Distributed Antenna Systems (DAS) are gaining widespread popularity in the indoor wireless market. Most of the existing research literature on this subject has focused on comparing the advantages of DAS systems with traditional macro cells. The goal of this thesis is to define a performance platform for CDMA based distributed antenna systems which can serve as essential design guidelines for future DAS deployments. One of the major issues presented by DAS systems is the noise floor rise in the reverse link caused by the DAS noise figure. This noise rise becomes a limiting factor in determining capacity and coverage of the DAS based network. The common practice of adding an attenuator (padding) in front of the Base Station receiver can bring down the noise floor, but at the same time force the mobile units to transmit at higher power. We establish an operating platform for the DAS so that the system can be effectively operated within the limits of mobile transmit power and base station receive power, maximizing the system capacity

Analytical modeling of HSUPA-enabled UMTS networks for capacity planning

In recent years, mobile communication networks have experienced significant evolution. The 3G mobile communication system, UMTS, employs WCDMA as the air interface standard, which leads to quite different mobile network planning and dimensioning processes compared with 2G systems. The UMTS system capacity is limited by the received interference at NodeBs due to the unique features of WCDMA, which is denoted as `soft capacity'. Consequently, the key challenge in UMTS radio network planning has been shifted from channel allocation in the channelized 2G systems to blocking and outage probabilities computation under the `cell breathing' effects which are due to the relationship between network coverage and capacity. The interference characterization, especially for the other-cell interference, is one of the most important components in 3G mobile networks planning. This monograph firstly investigates the system behavior in the operation of UMTS uplink, and develops the analytic techniques to model interference and system load as fully-characterized random variables, which can be directly applicable to the performance modeling of such networks. When the analysis progresses from single-cell scenario to multi-cell scenario, as the target SIR oriented power control mechanism is employed for maximum capacity, more sophisticated system operation, `feedback behavior', has emerged, as the interference levels at different cells depend on each other. Such behaviors are also captured into the constructed interference model by iterative and approximation approaches. The models are then extended to cater for the features of the newly introduced HSUPA, which provides enhanced dedicated channels for the packet switched data services such that much higher bandwidth can be achieved for best-effort elastic traffic, which allows network operators to cope with the coexistence of both circuit-switched and packet-switched traffic and guarantee the QoS requirements. During the derivation, we consider various propagation models, traffic models, resource allocation schemes for many possible scenarios, each of which may lead to different analytical models. All the suggested models are validated with either Monte-Carlo simulations or discrete event simulations, where excellent matches between results are always achieved. Furthermore, this monograph studies the optimization-based resource allocation strategies in the UMTS uplink with integrated QoS/best-effort traffic. Optimization techniques, both linear-programming based and non-linear-programming based, are used to determine how much resource should be assigned to each enhanced uplink user in the multi-cell environment where each NodeB possesses full knowledge of the whole network. The system performance under such resource allocation schemes are analyzed and compared via Monte-Carlo simulations, which verifies that the proposed framework may serve as a good estimation and optimal reference to study how systems perform for network operators

Analytical modeling of HSUPA-enabled UMTS networks for capacity planning

In recent years, mobile communication networks have experienced significant evolution. The 3G mobile communication system, UMTS, employs WCDMA as the air interface standard, which leads to quite different mobile network planning and dimensioning processes compared with 2G systems. The UMTS system capacity is limited by the received interference at NodeBs due to the unique features of WCDMA, which is denoted as `soft capacity'. Consequently, the key challenge in UMTS radio network planning has been shifted from channel allocation in the channelized 2G systems to blocking and outage probabilities computation under the `cell breathing' effects which are due to the relationship between network coverage and capacity. The interference characterization, especially for the other-cell interference, is one of the most important components in 3G mobile networks planning. This monograph firstly investigates the system behavior in the operation of UMTS uplink, and develops the analytic techniques to model interference and system load as fully-characterized random variables, which can be directly applicable to the performance modeling of such networks. When the analysis progresses from single-cell scenario to multi-cell scenario, as the target SIR oriented power control mechanism is employed for maximum capacity, more sophisticated system operation, `feedback behavior', has emerged, as the interference levels at different cells depend on each other. Such behaviors are also captured into the constructed interference model by iterative and approximation approaches. The models are then extended to cater for the features of the newly introduced HSUPA, which provides enhanced dedicated channels for the packet switched data services such that much higher bandwidth can be achieved for best-effort elastic traffic, which allows network operators to cope with the coexistence of both circuit-switched and packet-switched traffic and guarantee the QoS requirements. During the derivation, we consider various propagation models, traffic models, resource allocation schemes for many possible scenarios, each of which may lead to different analytical models. All the suggested models are validated with either Monte-Carlo simulations or discrete event simulations, where excellent matches between results are always achieved. Furthermore, this monograph studies the optimization-based resource allocation strategies in the UMTS uplink with integrated QoS/best-effort traffic. Optimization techniques, both linear-programming based and non-linear-programming based, are used to determine how much resource should be assigned to each enhanced uplink user in the multi-cell environment where each NodeB possesses full knowledge of the whole network. The system performance under such resource allocation schemes are analyzed and compared via Monte-Carlo simulations, which verifies that the proposed framework may serve as a good estimation and optimal reference to study how systems perform for network operators

Multi-carrier CDMA using convolutional coding and interference cancellation

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN016251 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Soft Handoff in MC-CDMA Cellular Networks Supporting Multimedia Services

An adaptive resource reservation and handoff priority scheme, which jointly considers the characteristics from the physical, link and network layers, is proposed for a packet switching Multicode (MC)-CDMA cellular network supporting multimedia applications. A call admission region is derived for call admission control (CAC) and handoff management with the satisfaction of quality of service (QoS) requirements for all kinds of multimedia traffic, where the QoS parameters include the wireless transmission bit error rate (BER), the packet loss rate (PLR) and delay requirement. The BER requirement is guaranteed by properly arranging simultaneous packet transmissions, whereas the PLR and delay requirements are guaranteed by the proposed packet scheduling and partial packet integration scheme. To give service priority to handoff calls, a threshold-based adaptive resource reservation scheme is proposed on the basis of a practical user mobility model and a proper handoff request prediction scheme. The resource reservation scheme gives handoff calls a higher admission priority over new calls, and is designed to adjust the reservation-request time threshold adaptively according to the varying traffic load. The individual reservation requests form a common reservation pool, and handoff calls are served on a first-come-first-serve basis. By exploiting the transmission rate adaptability of video calls to the available radio resources, the resources freed from rate-adaptive high-quality video calls by service degradation can be further used to prioritize handoff calls. With the proposed resource reservation and handoff priority scheme, the dynamic properties of the system can be closely captured and a better grade of service (GoS) in terms of new call blocking and handoff call dropping probabilities(rates) can be achieved compared to other schemes in literature. Numerical results are presented to show the improvement of the GoS performance and the efficient utilization of the radio resources

Final report on the evaluation of RRM/CRRM algorithms

Deliverable public del projecte EVERESTThis deliverable provides a definition and a complete evaluation of the RRM/CRRM algorithms selected in D11 and D15, and evolved and refined on an iterative process. The evaluation will be carried out by means of simulations using the simulators provided at D07, and D14.Preprin

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

Queueing Networks for Vertical Handover

PhDIt is widely expected that next-generation wireless communication systems will be heterogeneous, integrating a wide variety of wireless access networks. Of particular interest recently is a mix of cellular networks (GSM/GPRS and WCDMA) and wireless local area networks (WLANs) to provide complementary features in terms of coverage, capacity and mobility support. If cellular/ WLAN interworking is to be the basis for a heterogeneous network then the analysis of complex handover traffic rates in the system (especially vertical handover) is one of the most essential issues to be considered. This thesis describes the application of queueing-network theory to the modelling of this heterogeneous wireless overlay system. A network of queues (or queueing network) is a powerful mathematical tool in the performance evaluation of many large-scale engineering systems. It has been used in the modelling of hierarchically structured cellular wireless networks with much success, including queueing network modelling in the study of cellular/ WLAN interworking systems. In the process of queueing network modelling, obtaining the network topology of a system is usually the first step in the construction of a good model, but this topology analysis has never before been used in the handover traffic study in heterogeneous overlay wireless networks. In this thesis, a new topology scheme to facilitate the analysis of handover traffic is proposed. The structural similarity between hierarchical cellular structure and heterogeneous wireless overlay networks is also compared. By replacing the microcells with WLANs in a hierarchical structure, the interworking system is modelled as an open network of Erlang loss systems and with the new topology, the performance measures of blocking probabilities and dropping probabilities can be determined. Both homogeneous and non-homogeneous traffic have been considered, circuit switched and packet-switched. Example scenarios have been used to validate the models, the numerical results showing clear agreement with the known validation scenarios