Vijoy Pandey

Exploiting user profiles to support Differentiated Services in next-generation wireless networks

In the next-generation wireless network, user profiles such as the location, the velocity (both speed and direction), and the resource requirements of the mobile device can be accurately determined and maintained by the network on a per-user basis. We investigate the design of a Differentiated-Services architecture which exploits user profiles to maximize the network efficiency and which supports differentiated services classes, each with different quality-of-service (QoS) guarantees. In this paper, we provide implementation details of such an architecture for the Third-Generation Partnership Project (3GPP) network. The key underlying primitive of the architecture is the use of user profiles to perform advance resource reservation in target cells of the wireless cellular network. We identify the design tradeoffs and present performance results for an architecture consisting of two service classes, namely (1) a higher-cost profiled service with higher QoS, and (2) a lower-cost non-profiled service with best-effort QoS. Our analysis indicates that a significant decrease in the dropping probability - and, hence, higher QoS - can be guaranteed to users who subscribe to the profiled service. We examine the tradeoffs associated with some of the key system parameters including the reservation distance and the reservation granularity, and we determine their values which maximize the improvement in the dropping probability for all users.

A Call-Admission Control (CAC) Algorithm for Providing Guaranteed QoS in Cellular Networks

Future broadband wireless access systems are expected to integrate various classes of mobile terminals (MTs), each class with a different type of quality of service (QoS) requirement. When the load on a wireless network is high, the guarantee of QoS for each class of MTs is a challenging task. This study considers two classes of MTs—profiled MTs and nonprofiled or regular MTs. It is assumed that profiled users require a guaranteed QoS. The measure of QoS is the probability of forced termination of a call that was allowed to access the network. Two previous handoff prioritization schemes—(i) prerequest scheme and (ii) guard channel scheme—decrease handoff failure (and hence forced termination). In this work, we compare and contrast both the schemes through extensive simulation and we find that neither guard channel nor channel prerequest scheme can guarantee a desired level of QoS for the profiled MTs. We then propose a novel call-admission control (CAC) algorithm that can maintain any desired level of QoS, while the successful call completion rate is very high. In the proposed algorithm, the new call arrival rate is estimated continuously, and when the estimated arrival rate is higher than a predetermined level, some new calls are blocked irrespective of the availability of channels. The objective of this new call preblocking is to maintain a cells observed new call arrival rate at no more than the predetermined rate. We show that the proposed method can guarantee any desired level of QoS for profiled users.

Exploiting user profiles to support differentiated services in next-generation wireless networks

In the next-generation wireless network, user profiles such as the location, the velocity (both speed and direction), and the resource requirements of the mobile device can be accurately determined and maintained by the network on a per-user basis. We investigate the design of a wireless network architecture that exploits user profiles to maximize network efficiency and provide better quality-of-service (QoS) to different classes of users. In this article we provide implementation guidelines of such an architecture for the third-generation partnership project (3GPP) network. The key underlying primitive of the architecture is the use of both real-time and aggregate user profiles to perform advance resource reservation in the handoff target cells of the wireless cellular network. We identify various factors that can influence the efficiency of the resource reservation scheme, and through a simulation analysis of an example scenario we show the impact of these factors on the QoS that profiled users receive. The example scenario comprises two service classes: a high cost, profiled service with higher QoS; and a lower cost, non-profiled service with best-effort QoS. The results show that high QoS can be guaranteed to users who subscribe to the profiled service.

PRICING-BASED APPROACHES IN THE DESIGN OF NEXT-GENERATIONWIRELESS NETWORKS: A REVIEW AND A UNIFIED PROPOSAL

Unlike the bandwidth in a wired network, radio spectrum is a significantly scarce resource. This resource needs to be efficiently shared and reused by a number of users who may be simultaneously accessing a variety of mobile services. Thus, careful planning and management of the radio spectrum is required to maximize its value across all users and all accessed services. The evolving need for supporting differentiated services for novel multimedia applications in the wireless network adds a new dimension to this complex problem. Network researchers and architects are investigating the use of pricing to efficiently handle many of the corresponding network design and management issues. In this paper, we make two important contributions on this topic. First, we review the existing body of literature that attempts to utilize pricing in the design of next-generation wireless networks. Specifically, we classify the existing works into three categories: (a) pricing-based resource provisioning; (b) pricing-based static planning; and (c) pricing-based adaptive resource management. Second, we propose a unified pricing scheme which attempts to encompass the various design issues into a single comprehensive framework that can potentially lead to a scalable, differentiated-services wireless network architecture for the future.

Call admission and handoff control in multi-tier cellular networks: algorithms and analysis

In this paper, we investigate a call-admission and handoff-control framework for multi-tier cellular networks. We first propose and compare Call-Admission Control (CAC) algorithms based on the cell-dwelling time, by studying their impact on the handoff-call dropping and new-call blocking probabilities and the channel partitioning between the two tiers. Our results show that a simple, cell-dwelling-time-insensitive algorithm performs better under various mixes of user mobilities and call types. Moreover, there is an optimal channel partition of the overall spectrum between the tiers which minimizes the dropping and blocking probabilities for the two different CAC algorithms studied in this paper. Once the call is admitted into the network, we propose and compare various handoff- queuing strategies to reduce the call dropping probability. We show that implementing a queuing framework in one of the tiers (especially the upper, i.e., macrocellular, tier), results in a significant reduction in the dropping probability.

Performance issues in two-tier cellular networks

A two-tier cellular network consists of a number of small microcells overlayed by larger macro (umbrella) cells. Such a network can support improved quality of service (QoS), higher capacity, and larger coverage area than existing networks. In this work, we study the channel allocation problem for a two-tier cellular network for two types of calls (voice and data), under different degrees of handoff overheads. We also compare the impact of two typical call admission algorithms on network performance. We observe that, when minimal handoff overheads are present, allocating more channels to the microcell layer results in lower blocking and dropout probabilities. Second, there is an optimal orthogonal assignment of channels between the two tiers that minimizes the blocking and the dropout probabilities, when handoff overheads are significant, suggesting a hierarchical approach for designing handoff controllers. Finally, on comparing two typical call admission algorithms, we show that an algorithm that treats all calls identically performs better than an algorithm which tries to assign calls to different tiers based on their holding times.

Performance Improvements in Multi-Tier Cellular Networks

The goal of a Personal Communication System (PCS) is to provide a wide range of services, to multiple user types, at any location, and over multiple environments. Future cellular networks will be a central part of this goal and will therefore require improved quality of service (QoS), higher capacity, and a larger coverage area than existing networks. QoS can be improved if the system can achieve a lower new-call blocking probability and ensure that calls which are admitted into the system have lower failure rate (i.e., lower dropping probability). In order to increase the cellular network’s capacity, we can employ a finer mesh of smaller cells (i.e., microcells) over areas with a large population of users in order to achieve higher channel reuse. On the other hand, to be able to cover a larger area and serve a large number of highly-mobile hosts, we should increase the cell size.