In the offering of broadband wireless services a common objective for a service provider (carrier) is to choose a resource allocation policy for multiple service classes that maximizes profit. However, when doing so the policy may not be utility-optimal. This causes users to decrease their consumption, which leads to a decrease of profit for service providers. Therefore, a service provider should choose a Pareto-efficient resource allocation policy so that both the profit of the service provider and the utility of the users can be optimally balanced. In this paper, we develop a framework for finding the necessary and sufficient condition for Pareto-efficiency, derive the Pareto-efficient resource allocation policies and propose an efficient solution for achieving it in Orthogonal Frequency Division Multiplexing systems.

In the broadband mobile service market, it is reasonable that the carrier (service provider) should choose a Pareto-efficient resource allocation policy so that both the revenue of the carrier and the utility of users can be maximized. In this paper, we investigate the fundamental problem of the existence of resource allocation policies that are Pareto-efficient between the revenue and the utility. We show that the revenue-maximizing policy is not always equal to the utility-maximizing policy and that the two distinct policies, if any, generate a set of Pareto-efficient resource allocation policies. To make a Pareto-efficient resource allocation schedule, we develop a mathematical framework, where we study the existence of the Pareto-efficient policies, a necessary and sufficient condition for Pareto-efficiency, which can be used for finding the set of all the Pareto-efficient policies, and an efficient and exact solution method to find a Pareto-efficient resource allocation schedule.

Multimedia data often have different levels of importance such that more important bits are less error-tolerant. A new rate control method for transporting such multimedia data over parallel wireless links with heterogeneous reliability is proposed. Rate-controlled parallel transmissions (RCPT) of different layers of a multimedia stream with different levels of importance over a wireless channel that support multiple links with heterogeneous reliability can improve the efficiency in resource allocation while satisfying the quality of service requirement of the multimedia connection. To exploit RCPT, we present and evaluate a novel dynamic resource allocation method that decomposes the available radio resources into multiple sets of links with different levels of reliability. We mathematically formulate a rate control problem for the flexible RCPT scheme and develop an efficient real-time resource allocation algorithm with a remarkably fast rate of convergence. Simulation results show that the proposed method improves the utility and reduces the power consumed for delivery of a multimedia stream at the required quality of service, in comparison with a previous scheme, where different layers of each multimedia class are scheduled with dependency, and two schemes that provide homogeneous high or low reliability over all parallel links.

Slot allocation in a CDMA/TDD cellular network, which decomposes a frame into uplink and downlink slots, is a multi-dimensional optimization problem involving all the cells in the system due to interference between cells. However, the complexity of the problem makes it computationally too expensive to solve simultaneously for all the cells in a system of reasonable size. In this paper, we propose a novel predictive and distributed slot allocation scheme for transporting multimedia traffic over CDMA/TDD cellular networks with multiple cells, designed to maximize a general utility function that is (strictly) concave increasing. We formulate the utility-maximizing slot allocation problem as a nonlinear integer programming problem, and provide a solution that can be realized efficiently in a distributed manner. Also, we derive sufficient conditions for a real-number solution to be optimal and develop an efficient algorithm to find a near-optimal integer solution. The effectiveness of the integer solution is demonstrated by showing that its gap with the optimal solution is small. We show by experiments that the proposed predictive method has a sufficient accuracy when there are many active users in cells. Extensive simulation results show that the proposed distributed slot allocation method performs very well in comparison to an existing method.

The cellular relay network can provide both coverage extension and capacity enhancement. However, the network in nature requires more complex operation for maintaining each connection because of an increase dimension of node mobility that affects the signal-to-noise ratio (SNR) at each receiver node in the respective link in the relay architecture. As the outage ratio depends on the SNR statistics and the number of connections admitted in the system, admission capacity planning needs to take into account the SNR fluctuations. In this paper, we propose a new method for admission capacity planning in a cellular network using a cooperative relaying mechanism called decode-and- forward. Our approach is based on a new consideration of the randomness of the channel gain in our formulation of the outage ratio. Admission capacity planning is mathematically formulated as an optimization problem that maximizes the accommodation capacity (in number of connections) subject to a constraint that the outage ratio is upper-bounded by a certain threshold value. The simplicity of the problem formulation facilitates its solution in real-time. The proposed planning method provides an attractive means for dimensioning a cellular relay network with cooperative relay nodes.

Most previous work on cooperative cellular networks has considered homogeneous relaying architectures where all nodes act as both sources and relays or considered heterogeneous relaying architecture where relays are fixed. In this paper, we examine the power consumption performance of heterogeneous cooperative cellular networks with two classes of nodes: source nodes (subscriber stations, SS's) that do not act as relays, and relaying agents (relays station, RS) that are dedicated to relaying functions with little concern about power consumption. In this architecture, source nodes are able to reap the benefits of cooperative communication, such as improvements in the achievable data rate and reductions in the transmit power, while reducing the overall power consumption since they do not act as a relay. We consider a geometry of a cell. Then we consider random locations of SS and RS, respectively, to analyze the average power consumption over the region of interest under the assumption that the SS and RS are distributed uniformly over the cell region.

This paper proposes an improved version of time-division duplex (TDD) mode called slot-splitting TDD (SS-TDD), which increases the average achievable capacity of a TDD cellular network by splitting a slot. The improvement results from partial relaxation of the restriction in the former versions of TDD, which requires an integer number of downlink slots. The proposed method can be implemented with no significant increase in computational complexity. In addition, with a few minor modifications, the proposed SS-TDD can be applied to two out of three burst types in UTRA TDD with a single-switching-point configuration. In a multi-cell environment with mixed traffic, our analysis shows that the proposed SS-TDD increases the average cell capacity (in Mbps) by up to 18.5-10.0%, and the Erlang capacity by up to 20.5-44.3%, for targeted SIRs in the range of 5-7dB.

In this paper, we consider deployment of a wireless mesh network (WMN) to interconnect a video sensor network (VSN) and improve its energy efficiency. We propose a scheduling method for mesh nodes that performs fair scheduling if there is sufficient link capacity, and perform traffic grooming followed by scheduling using a novel constraint relaxation method if link capacity is insufficient. The resulting improvement in energy efficiency of the VSN is evaluated. Results show remarkable savings in power consumption of sensor nodes when a VSN is interconnected with a WMN: energy consumption in the VSN is reduced by approximately 55-79% when the probability that a sensor node can forward traffic to a mesh node is 50%

A rate scheduling method for multimedia connections over parallel wireless channels with heterogeneous reliability is developed. Transmissions of different parts of a multimedia stream with different level of error tolerance over a wireless channel that support multiple links with heterogeneous reliability can improve the flexibility in resource allocation and increase the number of multimedia streams admitted by the system while satisfying the QoS requirement of each connection. To address this transmission scenario, we present and evaluate a novel dynamic resource-allocation method that decomposes the available resources into two sets of links, one with higher reliability (lower BER) than other, and allocates the links to the respective parts of each multimedia connection. We mathematically formulate a rate scheduling problem for the flexible transmission scenario and develop an efficient real-time resource allocation algorithm with a remarkably fast rate of convergence. Simulation results show that the proposed method improves: the number of multimedia connections by 1.25%-34.6% according to the error rate in wireless link; the average number of multimedia connections that experience errors per frame by 1%-70%for low rate connections and by 5%-14%for high rate connections

This paper presents a new fair scheduling scheme for orthogonal frequency-division multiple-access-based wireless mesh networks (WMNs), which fairly allocates subcarriers and power to mesh routers (MRs) and mesh clients to maximize the Nash bargaining solution fairness criterion. In WMNs, since not all the information necessary for scheduling is available at a central scheduler (e.g., MR), it is advantageous to involve the MR and as many mesh clients as possible in distributed scheduling based on the limited information that is available locally at each node. Instead of solving a single global control problem, we hierarchically decouple the subcarrier and power allocation problem into two subproblems, where the MR allocates groups of subcarriers to the mesh clients, and each mesh client allocates transmit power among its subcarriers to each of its outgoing links. We formulate the two subproblems by nonlinear integer programming and nonlinear mixed integer programming, respectively. A simple and efficient solution algorithm is developed for the MR's problem. Also, a closed-form solution is obtained by transforming the mesh client's problem into a time-division scheduling problem. Extensive simulation results demonstrate that the proposed scheme provides fair opportunities to the respective users (mesh clients) and a comparable overall end-to-end rate when the number of mesh clients increases

In future satellite multimedia networks, the high speed of a mobile satellite may give rise to a higher number of handovers and rapid change of traffic condition. In this paper we propose an adaptive admission control scheme based on the estimation of near future traffic load and probabilistic bandwidth reservation. The amount of bandwidth for admitting handover requests in a near future is estimated based on probability distribution estimated from historic data. Optimization model is developed, in a distributed manner, to determine adequate amount of bandwidth to reserve according to realtime network traffic condition. With this, an efficient and exact solution algorithm using optimality condition is also studied based on mathematical programming. Our scheme could he utilized as a guideline for cost-effective radio resource management in mobile multimedia networks.

With a microcell or low earth orbit (LEO) satellite multi-beam strategy, high reuse efficiency is achieved. However, microcells and/or LEO multi-beams may give rise to a great number of handovers. Each handover requires network resources to reroute the corresponding call to a new base station, it is preferred to have as few handovers as possible to decrease the processing burden. New call attempts generated near cell boundaries usually request handovers very soon. This phenomenon may cause unnecessary handover processing burden and too much bandwidth reservation. We suggest a selective admission control scheme in order to resolve the drawback of the phenomenon. Performance analysis shows that our scheme improves handover performance without sacrificing new call blocking performance.

Since the digital video broadcast-return channel via satellite (DVB-RCS) standard was released in 2000, developing an interactive satellite multimedia (ISM) network has become a hot issue. In order to provide high-speed multimedia services using a DVB-RCS system, it is important to efficiently and dynamically assign the timeslots to a number of terminals according to their various demands. Also, it is imperative to improve the degradation of link quality due to rain-fade attenuation in Ka-band satellite communications. As a result, multirate superframe structures should be implemented for a relatively low data rate at the cost of stable connection to terminals in rain-fade regions and a relatively high data rate to terminals in clear-sky regions. Timeslot scheduling in this environment is studied in this paper. We mathematically formulate the timeslot assignment problem as a nonlinear integer programming problem and develop an efficient real-time solution algorithm. Extensive simulation results show that our algorithm successfully finds a feasible solution with optimality gap less than 0.05% within about 5 ms at Pentium III PC. We believe that our algorithm can be utilized as a guideline in developing real-time timeslot assignment algorithms for ISM networks.

The CDMA/shared-TDD system is a highly attractive solution to support the next generation cellular mobile systems which provide unbalanced multimedia services. In this paper, we analyze the interference for downlink, uplink, and crossed timeslots in a multicell CDMA/shared-TDD system. We also mathematically formulate optimal timeslots and channel allocation problem, which is to maximize the system capacity under the given traffic unbalance. Computational experiments show that the capacity of the CDMA/shared-TDD system is larger than that of the pure CDMA/TDD system.