Emanuel B. Rodrigues

Packet Scheduling for VOIP Over HSDPA in Mixed Traffic Scenarios

By means of dynamic system-level simulations, this work evaluates whether the studied packet scheduling (PS) algorithms are capable of guaranteeing the quality of service (QoS) of the voice over IP (VoIP) on a scenario where the VoIP and Web browsing services will compete for the same resources. Two sets of algorithms were considered: QoS-differentiated and non-QoS-differentiated algorithms. It can be concluded that, in general, the PS algorithms able to perform QoS differentiation presented better performance in terms of system capacity and QoS compared to those non-QoS-differentiated algorithms. Among the former category, those that take into consideration delay requirements of the VoIP service presented the best overall capacity for all traffic mixes

Radio resource allocation framework for quality of experience optimization in wireless networks

This article presents a QoE-aware resource assignment and power allocation framework aiming at maximizing the minimum MOS of the users in a wireless network. It considers a satisfaction factor, that is, a requirement related to the minimum number of users that should be satisfied. This requirement is an important aspect from the operators point of view and has not yet been studied in this context, as far as we know. The proposed method is evaluated by means of simulations, and the obtained results show that it outperforms existing solutions, and performs close to the optimal solution as well. The performance evaluation demonstrates that the satisfaction factor is a good solution to deal with heavily loaded systems.

Packet scheduling for Voice over IP over HSDPA in mixed traffic scenarios with different end-to-end delay budgets

By means of dynamic system-level simulations, this work evaluates whether the studied Packet Scheduling (PS) algorithms are capable of guaranteeing the quality of service (QoS) of the voice over IP (VoIP) on a scenario where the VoIP and Web browsing services will compete for the same resources and there is a maximum allowed end-to-end delay for VoIP packets. Two sets of algorithms were considered: QoS-differentiated and non-QoS-differentiated algorithms. It was verified the system capacity gains when the VoIP delay budget is increased. Regarding the PS performance, those algorithms able to perform QoS differentiation presented better performance in terms of system capacity and QoS compared to those non-QoS-differentiated algorithms. Among the former category, those that take into consideration delay requirements of the VoIP service presented the best overall capacity for all traffic mixes and delay budgets.

Power-based congestion control framework for downlink WCDMA systems

This paper proposes and evaluates power-based congestion control mechanisms in the WCDMA downlink air interface based on the functionalities of the call admission control (CAC), conversational service class rate adaptation (RA) via AMR codec and load control (LC) algorithms. It is verified by means of dynamic system level simulations that the congestion control technique is capable of guaranteeing the users QoS requirements even for high offered loads.

Maximization of user satisfaction in OFDMA systems using utility-based resource allocation

In order to keep and/or expand its share of the wireless communication market and decrease churn, it is important for network operators to keep their users clients satisfied. The problem to be solved is how to increase the number of satisfied non-real time NRT and real time RT users in the downlink of the radio access network of an orthogonal frequency division multiple access system. In this context, the present work proposes a method to solve the referred problem using a unified radio resource allocation RRA framework based on utility theory. This unified RRA framework is particularized into two RRA policies that use sigmoidal utility functions based on throughput or delay and are suitable for NRT and RT services, respectively. It is demonstrated by means of system-level simulations that a step-shaped sigmoidal utility function combined with a channel-aware opportunistic scheduling criterion is effective toward the objective of user satisfaction maximization. Copyright

Resource Allocation for Improved User Satisfaction with Applications to LTE

Cellular networks have experienced a strong development in the past decades and the technology evolution to meet the continued steep increase of mobile traffic expected for the next years is an important challenge. In this context, cellular operators have as objective to increase the number of satisfied users in the system whereas users or subscribers aim at having fulfilled their expected quality of service. In order to increase the number of satisfied users in the system we identify radio resource allocation as a key functionality. Radio resource allocation is responsible for managing and distributing the available scarce resources of the radio interface to the active connections. In this chapter, we present radio resource allocation strategies with multiple antennas at the transmitter and/or receivers to increase the number of satisfied users in cellular networks based on two approaches: heuristic and utility-based strategies. While the heuristic design provides simple and quick solutions to the radio resource allocation problems, the utility-based approach is a flexible and general tool for radio resource allocation design. Simulation results show that the proposed algorithms following these design guidelines are able to achieve high number of satisfied users in modern networks.

QoS and load management via admission control in UMTS forward link

In downlink WCDMA systems, QoS and load management can be performed by a call admission control (CAC) algorithm. The objective of CAC is to guarantee high capacity and system stability, by accepting or denying an arriving bearer service access to the system, depending on the system load, the interference it adds to and receives from the existing connections, and the base station (BS) power limitation. Our contribution envisages the proposal of a flexible CAC framework regarding handover resource reservation, traffic activity monitoring and initial power allocation, in order to maximize the system capacity, while meeting quality of service (QoS) requirements throughout the dynamism of the connection duration.

Evaluation of Fixed Thresholds for Allocation and Management of Dedicated Channels Transmission Power in WCDMA Networks

The major goal of this contribution is to evaluate strategies for allocation and management of the Dedicated Traffic Channels (DCH) transmission power in a WCDMA radio access network. The power allocation and control solution is tested aiming power consumption saving while the system QoS requirements are kept in acceptable levels. We focus on multi-cellular dynamic system-level simulations of the WCDMA radio access network in the forward link for the conversational service class. From these investigations we address the feasibility of our solution.

Capacity, Fairness, and QoS Trade-Offs in Wireless Networks with Applications to LTE

Wireless mobile network optimization is a complex task that consists in achieving different design objectives such as spectral efficiency, energy efficiency, fairness, and quality of service. Radio resource allocation is responsible for managing the available resources in the radio access interface and, therefore, is an important tool for optimizing networks and achieving the designed objectives mentioned previously. However, in general all these network design objectives cannot be achieved at the same time by resource allocation strategies. In fact, different resource allocation strategies can be designed to maximize one objective in detriment of the other as well as to balance the objectives. In this chapter we deal with important trade-offs between contradicting objectives in modern wireless mobile networks: capacity versus fairness and capacity versus satisfaction. We present resource allocation strategies that can achieve static and adaptive performances when the previously mentioned trade-offs are considered. In order to design the resource allocation strategies we consider heuristics and utility-based solutions. System-level simulations show that the proposed techniques are powerful tools to the network operator, since they can decide in which trade-off point of the capacity-fairness or capacity-satisfaction planes they want to operate the system.

A software development framework based on C++ OOP language for link-level simulation tools

This article introduces a software development framework, which amasses object-oriented programming (OOP) concepts and designed procedures, intended to systematize the implementation of link-level simulation tools. This development framework is fully implemented in C++ programming language providing modularity and reusability (improving the coding activity). This framework then constitutes remarkable tool for quickly creating link-level applications. Aiming to evaluate the applicability of this software structure, the conversational service class transmitting at 12.2 kbps and over the Wideband CDMA (WCDMA) Downlink (DL) dedicated channel (DCH) is addressed as a case-study and therefore potential benefits of utilizing such development library are identified. It is shown that the development framework provides flexibility for the software development of link-level simulators remarkably reducing the design, programming and testing stages.