Load Balancing is typically used in cellular wireless networks in the frequency domain to balance paging, access, and traffic load across the available bandwidth. In this paper we extend the concept of Load Balancing to the Spatial domain. We develop two approaches - Network Load Balancing and Single-Carrier MultiLink - for Spatial Load Balancing. While these techniques are applicable to both cellular wireless networks and WiFi networks we illustrate them on EV-DO (a 3G cellular data network). Both these methods apply when the device has more than one candidate server and determine the server(s) using not only the channel quality from the server to the device but also the current load on each server. The proposed techniques leverage existing cellular (EV-DO) network architecture and are fully backward compatible. Network operators can realize both a substantial increase in network capacity and deliver a notable improvement in user experience by applying these techniques. The combination of load balancing in the frequency domain (Smart Carrier Management and multi-carrier) and spatial domain improves the connectivity within a network, enabling an optimal allocation of resources under the p-fair criterion.

We pose a network-wide scheduling problem for cellular wireless networks in which users are capable of being served by several schedulers on the downlink, though not jointly. We present a distributed algorithm, with limited communication across servers, that solves this problem optimally, in that it gives the network-wide proportional fair solution. An idealized version is presented first, in which all users are capable of being served by all schedulers and in which all the decision-making takes place among the schedulers alone. A practical version is also presented, in which users play a role in choosing their servers and servers decide how to allocate resources to the users that choose them. The practical version can achieve the same optimum as the idealized one and gives gains up to 60% in typical network deployments. This version can be implemented on any wireless technology to achieve optimal network scheduling. We have focused particularly on LTE, HSPA and 1xEV-DO and the first commercial deployment will soon occur on the 1xEV-DO system, based on the 3GPP2 standard, under the rubric of `Smart Networks.

This paper studies the effects of heterogeneity in DO networks and proposes measures for reducing or removing them. In particular, two types of imbalance, i.e., f-Imbalance and OH-Imbalance are identified and methods for compensating them, i.e., RL padding and AT overhead (OH) channel boost, are proposed. The effectiveness of the proposed methods is demonstrated through both, developing an analytic model and conducting comprehensive simulations. The main conclusion of the paper is that through a combination of methods such as partial RL padding of weaker cells and OH channel boost of AT's, it is possible to compensate for the potentially severe imbalance conditions that heterogeneity brings about to DO networks.

This paper studies the different uses of repeaters and remote radioheads (fiber repeaters) in cellular networks. Traditional uses include coverage extension and eliminating points of pilot pollution (three-way handoff). In addition, we find that careful placement of repeaters can improve capacity substantially. We also find that in layouts where some sectors are much more heavily loaded than others, remote radioheads can be used to transfer load from heavily loaded to lightly loaded sectors, thereby improving network capacity. Therefore, repeaters can enhance network performance without changing either the software or the hardware of existing layouts.

Uplink-downlink imbalance is a characteristic of all wireless networks which greatly impacts system performance, and must be accounted for in system design and simulation. However this property seems to have received sparse attention in literature. This paper describes imbalance, its potential sources, audits impact on traffic and overhead channel performance, soft handoff adaptive server selection, and sector load control schemes. This paper defines imbalance metrics, a model for simulating antenna imbalance, and presents simulation study of system robustness to link imbalance using cdma2000 1xEV-DO as an example.

Quality-of-service (QoS) routing between domains is an essential component for providing service differentiation in the Internet. State aggregation is a technique that makes QoS routing scalable to large internetworks, by presenting a concise and accurate representation of the domain to the routing process. The concept of using a domain's routing capacity as a bandwidth aggregate has been in existence for some time. However, no methodology has been suggested in the literature for its estimation and usage. Also, the impact of a domain's routing capacity on the routing performance has not been studied before. This paper aims to fill these voids by presenting a framework based on "network flows" for estimating a domain's routing capacity and evaluating its efficacy on the routing performance. The routing capacity is used in conjunction with the conventional widest path bandwidth as the domain aggregate. Analytical and experimental results show that appropriate use of routing capacity along with the widest path bandwidth reduces the tendency of the advertised aggregate to overestimate bandwidth availability, and makes the routing process more robust to the frequency of domain state updates. During periods of congestion, the use of routing capacity can improve the bandwidth admitted into the network by as much as 20%

In this correspondence, we examine the relationship between Dempster-Shafer (DS) decision making systems and conventional Bayesian (centralized or distributed) detectors. We establish theoretically that under certain intuitively pleasing DS probability mass assignments the two systems become equivalent. A few numerical studies illustrate the theoretical developments.

cdma2000 1/spl times/EV-DO release 0 (DO ReL. 0), also known as IS-856, is a third generation (3G) wireless solution to providing wide-area high-speed mobile Internet access. cdma2000 1/spl times/EV-DO revision A (DO Rev. A) system provides enhancements to DO Rel. 0, such as higher spectral efficiency and advanced quality-of-service (QoS) support. In this paper we evaluate the reverse link performance of DO Rev. A system from a physical layer perspective. Specifically, we obtain DO Rev. A reverse link capacity via analysis as well as system simulations with complete modeling of physical- and MAC-layer dynamics. We show that DO Rev. A achieves significant capacity gain over DO Rel 0 in supporting delay-sensitive applications and provides flexible tradeoff in delay, capacity and physical-layer error-rate performance based on QoS requirement. Under moderate sector loading, DO Rev A achieves a reverse link sector capacity on the order of 600-700 kbps with two receiving antennas, i.e. a two-to-three fold improvement over DO Rel 0, while using the same 1.25 MHz of spectrum. Furthermore, sector throughput on the order of 1.2 Mbps is achievable with four receiving antennas, in the form of spatial array or pairs of cross-polarized (X-pol) antennas.

Quality of service (QoS) routing between domains is indispensable for deploying QoS in the Internet. State aggregation is a technique that makes QoS routing scalable to large networks. As the impreciseness in the advertised aggregate adversely affects the performance of the QoS routing process, it is important to investigate the accuracies of various aggregation schemes. In this paper, we study the efficacy of a new bandwidth aggregation scheme, and compare our scheme's performance with that of the existing schemes. Our analytical and experimental studies show that for active networks, the proposed aggregation scheme is more accurate, and gives a better routing performance than the current schemes.

QoS routing is the process of routing a connection based on the connection's resource requirements. The overhead involved in QoS routing increases with the network size. State aggregation is an important technique that makes QoS routing scalable. We propose a new domain state aggregation technique based on "network-flows", for stochastic networks. We propose a new fast heuristic algorithm to estimate the PMF of "maximum-flow" through a probabilistic flow network. Using this algorithm, we aggregate the bandwidth information in a domain and use it along with the path aggregate for routing. Through simulations, we show that stochastic estimation of traffic capacity is better than deterministic estimation and gives a better bandwidth admission ratio when compared with existing state aggregation techniques.

Multimedia applications such as video-conferencing, telemedicine, HDTV, etc. have very stringent quality-of-service (QoS) demands and require a connection-oriented service. For these applications, a path satisfying their requirements in terms of bandwidth, delay buffer, etc. needs to be found. As conventional IP routing is based only on hop counts, it is not suitable for multimedia applications. It is clear that, to route requests that have QoS requirements, existing routers should be made QoS aware and the packet forwarding should be based on QoS parameters. Also, routing protocols like OSPF and RIP must be extended suitably to facilitate QoS routing. The goal of QoS routing algorithms is to find a loop-less path satisfying a given set of constraints on parameters like bandwidth, delay, etc. The path selection process could return either the entire path to the destination or the best next hop for the request. The first case is called "source routing" and the second is referred to as "distributed routing". In this paper, we propose a new distributed QoS routing algorithm for unicast flows, which has a very low call establishment overhead. Our algorithm makes use of existing IP routing protocols such as OSPF and RIP with minimal modifications.

The goal of QoS routing is to find a loopless path through a network that can satisfy a given set of constraints on parameters such as bandwidth, delay and cost. QoS routing algorithms can be classified into three categories. They are source routing, distributed routing and hierarchical routing. In this paper we propose a distributed QoS routing algorithm that gives high call admission rates in a congested network for constraints on metrics like bandwidth, buffer, and CPU usage with a low message complexity.