One of the most important features of the evolving Fourth Generation (4G) wireless communication system is heterogeneous wireless access in which users could connect to several wireless access networks simultaneously. The new feature brings new challenges for the bandwidth allocation (BA) among heterogeneous networks. A non-cooperative bandwidth allocation game (NCBAG) algorithm for heterogeneous wireless networks is proposed in this paper. A BA problem is modeled as a non-cooperative game, and formulated to maximize the total utility of different networks. The existence of Nash equilibrium is verified for the proposed game model. The utility functions are developed for different applications to avoid assigning too much bandwidth to single user. Simulation results show that our proposed scheme can not only achieve high utility, but also reduce the blocking probability within a few steps of iteration.

A Non-Cooperative Game Approach for Bandwidth Allocation in Heterogeneous Wireless Networks

This paper illustrates the optimization of design parameters for quality-of-service (QoS) aware packet schedulers in multi-service environments with WCDMA/HSDPA. The optimization sets the objective of maximizing the cell throughput while meeting certain minimum QoS criteria and focuses on two variants of the proportional fair with barrier function (PF-B) family of schedulers and on the proportional fair with required activity detection. The assessment on the sensitivity of the scheduler parameters to the traffic load and mixture is evaluated in scenarios with both real-time (streaming) and non real-time type of users (web browsing). This study shows that the PF-B schedulers require a per scenario dedicated optimization, while PF-RAD is quite insensitive and robust to support a general traffic mix. Overall, PF-RAD significantly outperforms PF-barrier schedulers in the investigated scenarios, providing up to 100% streaming cell throughput gain.

Optimization of QoS-aware Packet Schedulers in Multi-Service Scenarios over HSDPA

Voice over Internet Protocol (VoIP) allows communication of voice and/or data over the internet in less expensive and reliable manner than traditional ISDN systems. This solution typically allows flexible interconnection between organization and companies on any domains. Cloud VoIP solutions can offer even cheaper and scalable service when virtualized telephone infrastructure is used in the most efficient way. Scheduling and load balancing algorithms are fundamental parts of this approach. Unfortunately, VoIP scheduling techniques do not take into account uncertainty in dynamic and unpredictable cloud environments. In this paper, we formulate the problem of scheduling of VoIP services in distributed cloud environments and propose a new model for biobjective optimization. We consider the special case of the on-line nonclairvoyant dynamic bin-packing problem and discuss solutions for provider cost and quality of service optimization. We propose twenty call allocation strategies and evaluate their performance by comprehensive simulation analysis on real workload considering six months of the MIXvoip company service.

/pdf/biobjective-voip-service-management-in-cloud-infrastructure-348iuacg43.pdf

Biobjective VoIP Service Management in Cloud Infrastructure

HSDPA (high-speed downlink packet access), introduced in WCDMA release 5, provides a high-bandwidth shared channel with short transmission time interval (TTI). The short TTI together with appropriate scheduling enable HSDPA to support efficient multiplexing of traffic. We explain the performance of four scheduling algorithms when transmitting a traffic mix consisting of both conversational (VoIP) traffic and background (Web) traffic over the high-speed downlink shared channel (HS-DSCH) of HSDPA. We consider both cell throughput and user satisfaction. The proportional fair (PF), the maximum rate (MR) scheduler and two extended versions of MR, are tested for different VoIP scheduling delay budgets and varying load. To understand the behaviour of the schedulers, we use the ns-2 simulator extended with a model of HS-DSCH to simulate a mixed traffic scenario. Our results show that a scheduler that gradually increases the VoIP priority and considers the user's current possible rate, performs well. A more drastic increase in VoIP priority is however needed when the delay budget is short. Furthermore, attempting to uphold quality for both VoIP and Web traffic makes the system sensitive to overload situations.

/pdf/scheduling-support-for-mixed-voip-and-web-traffic-over-hsdpa-1yrhko1s91.pdf

Scheduling Support for Mixed VoIP and Web Traffic over HSDPA

Through the introduction of the third generation of mobile cellular network technologies a major step towards a ubiquitious and wireless access to the Internet has been taken. There are however sti ...

Congestion control in wireless cellular networks

We have implemented functionality from the High Speed Downlink Packet Access (HSDPA) mode as an extension to ns-2 (the Network Simulator version 2). Ns-2 is a well-known simulation platform frequen ...

An NS module for simulation of HSDPA

HS-DSCH is a high-speed shared radio channel extension for WCDMA which is used for cellular mobile telephony. The algorithm for distributing the channel resources together with the characteristics ...

On the TCP minimum retransmission timeout in a high-speed cellular network

HS-DSCH is a high-speed shared radio channel extension for WCDMA which is used for cellular mobile telephony. The algorithm for distributing the channel resources together with the characteristics of the radio medium result in delay variations. The TCP minimum retransmission timeout interval has effectively alleviated delay variations in its range from deteriorating TCP performance. But recently, this bound has been shortened in modern widely spread TCP implementations. The aim of our study is to find out how a shorter minimum retransmission timeout affects TCP performance over HS-DSCH. We have implemented a model of HS-DSCH in the network simulator ns-2. Our simulations cover a wide range of different minimum retransmission timeout settings and loads, two types of schedulers (Round-Robin and Signal-to- Interference-Ratio (SIR) scheduling) and two versions of TCP (SACK and NewReno). Our results show that the number of spurious timeouts increase with the load. The SIR scheduler causes fewer spurious timeouts than the RR scheduler for shorter minimum retransmission timeout settings, however, for longer settings the RR scheduler causes fewer spurious timeouts compared to the SIR scheduler. The minimum retransmission timeout has consequences for goodput fairness, but it does not affect the total system throughput. Both TCP versions produced similar results.

/pdf/on-the-tcp-minimum-retransmission-timeout-in-a-high-speed-378gv7o86f.pdf

On the TCP Minimum Retransmission Timeout in a High-speed Cellular Network

In this paper we investigate the need for admission control for the high-speed downlink shared channel (HS-DSCH) through the evaluation of two admission control mechanisms. One mechanism uses the number of active users in a cell as a metric and the other one uses the mean downlink throughput of a user. We also introduce a model for user behaviour in which the goodput of a completed file download decides if further downloads are made. In order to measure user-experienced quality we use a utility function for transforming per-flow goodput into a user satisfaction index. System performance, measured by total user satisfaction and total goodput, is evaluated for a range of session arrival rates and admission control limits. This evaluation is done using the ns-2 simulator, together with extensions of our own. If the objective is to maximise goodput, our results show that no admission control is needed. Maximising user satisfaction benefits from an admission control. We also note that the impact of user behaviour is not insignificant.

/pdf/on-the-influence-of-user-behaviour-and-admission-control-on-j61dj18197.pdf

Mats Folke

Papers

Scheduling Support for Mixed VoIP and Web Traffic over HSDPA

An NS module for simulation of HSDPA

On the TCP minimum retransmission timeout in a high-speed cellular network

On the TCP Minimum Retransmission Timeout in a High-speed Cellular Network

On the Influence of User Behaviour and Admission Control on System Performance in HS-DSCH