A Fair and Efficient Packet Scheduling Scheme for IEEE 802.16 Broadband Wireless Access Systems

This paper proposes a fair and efficient QoS scheduling scheme for IEEE 802.16 BWA systems that satisfies both throughput and delay guarantee to various real and non-real time applications. The proposed QoS scheduling scheme is compared with an existing QoS scheduling scheme proposed in literature in recent past. Simulation results show that the proposed scheduling scheme can provide a tight QoS guarantee in terms of delay, delay violation rate and throughput for all types of traffic as defined in the WiMAX standard, thereby maintaining the fairness and helps to eliminate starvation of lower priority class services. Bandwidth utilization of the system and fairness index of the resources are also encountered to validate the QoS provided by our proposed scheduling scheme

Dynamic bandwidth scheduling and burst construction algorithm for downlink in (4G) mobile WiMAX networks

Advanced wireless systems, also called fourth generation (4G) wireless systems, such as Mobile Worldwide interoperability for Microwave Access (WiMAX), are developed to provide broadband wireless access in true sense. Therefore, it becomes mandatory for such kind of systems to provide Quality of Service (QoS) support for wide range of applications. In such types of systems, wireless base stations are responsible for distributing proper amount of bandwidth among different mobile users, thus satisfying a user’s QoS requirements. The task of distributing proper amount of bandwidth rests upon a scheduling algorithm, typically executed at the base station. 2G and 3G wireless systems are able to provide only voice, low data rate, and delay insensitive services, such as Web browsing. This is due to the lack of development in digital modulation and multiple access schemes, which are two major aspects of physical layer of these systems. Digital modulation is used to combat with location-dependent channel errors which get introduced in the data transmitted by base station on a wireless channel to a mobile station. Hence, different locations of every mobile station in a cell coverage area require different modulation and coding schemes for error-free transmission. Link adaptation is a technique that makes the use of variable modulation and coding schemes possible, according to varying location of mobile stations. This technique is used by 4G systems to achieve error free transmissions. 2G and 3G systems are not capable of achieving error-free transmissions in many cases due to significantly fewer or no choice of modulation and coding schemes for different locations of mobile stations. In such cases, most of the time, wireless channel is either error-prone or error-free for mobile station. Scheduling algorithms developed for 2G and 3G systems focussed on providing long term average rate requirements of users, which are satisfied at the expense of zero transmission for mobile users experiencing bad or error prone channel. This approach was adopted to achieve efficient use of wireless channel capacity. This was the best approach adopted by majority of scheduling algorithms because delay sensitive applications were not supported in such systems and hence bounded delay was not a matter of concern. Hence, the majority of the algorithms focussed on providing long term average rate requirements while maximizing cell throughput. This helped in making efficient use of wireless channel capacity at the expense of zero transmission for mobile users experiencing bad channel and compromising delay performance. These approaches, however, will not be suitable for 4G systems as such systems support wide range of applications ranging from delay-insensitive to highly delay-sensitive. Hence in this thesis, a dynamic bandwidth scheduling algorithm called Leaky Bucket Token Bank (LBTB) is proposed. This algorithm exploits some advanced features of 4G systems, like link adaptation and multiple access scheme, to achieve long term average rate requirements for delay-insensitive applications and bounded delay for delay-sensitive applications. Advanced features of 4G systems also bring more challenges. One such challenge is Orthogonal Frequency Division Multiple Access (OFDMA), a multiple access scheme deployed in 4G systems. In OFDMA, scheduled data for different mobile stations is packed into bursts and mapped to a two dimensional structure of time and frequency, called OFDMA frame. It has been observed that the way bursts are mapped to OFDMA frame affects the wakeup time of mobile stations receiving data and therefore causes power consumption. Wakeup time is the time duration in OFDMA frame for which the mobile station becomes active. Since OFDMA frame is a limited and precious radio resource, the efficient use of such radio resource is necessary. Efficient use requires that the wastage of such radio resource be minimized. Hence in this thesis, a burst construction algorithm called Burst Construction for Fairness in Power (BCFP) is also proposed. The algorithm attempts to achieve fairness in power consumption of different mobile stations by affecting their wakeup time. It also attempts to minimize wastage of radio resources. For comparing the performance of joint proposed algorithms (LBTB+BCFP), the proposed burst construction algorithm (BCFP) is joined to the two other existing scheduling algorithms namely: Token Bank Fair Queuing (TBFQ) and Adaptive Token Bank Fair Queuing (ATBFQ). TBFQ is an algorithm developed for 3G wireless networks whereas, ATBFQ is an extension to the TBFQ and is developed for 4G wireless networks. Therefore, the performance of the proposed algorithms jointly together (LBTB+BCFP) is compared with the joint TBFQ and proposed burst construction algorithm (TBFQ+BCFP), as well as joint ATBFQ and proposed burst construction algorithm (ATBFQ+BCFP). We compare the performance in terms of average queuing delay, average cell throughput, packet loss, fairness among different mobile users, fairness in average wakeup times (average power consumption), and fraction of radio resources wasted. The performance of proposed burst construction algorithm (BCFP) is also compared with Round Robin algorithm in terms of fairness in average power consumption as well as fraction of radio resources wasted, for varying number of users

A quality of service architecture for WLAN-wired networks to enhance multimedia support

Includes abstract.Includes bibliographical references (leaves 77-84).The use of WLAN for the provision of IP multimedia services faces a number of challenges which include quality of service (QoS). Because WLAN users access multimedia services usually over a wired backbone, attention must be paid to QoS over the integrated WLAN-wired network. This research focuses on the provision of QoS to WLAN users accessing multimedia services over a wired backbone. In this thesis, the IEEE 802.11-2007 enhanced data channel access (EDCA) mechanism is used to provide prioritized QoS on the WLAN media access control (MAC) layer, while weighted round robin (WRR) queue scheduling is used to provide prioritized QoS at the IP layer. The inter-working of the EDCA scheme in the WLAN and the WRR scheduling scheme in the wired network provides end-to-end QoS on a WLAN-wired IP network. A mapping module is introduced to enable the inter-working of the EDCA and WRR mechanisms

Connection admission control and packet scheduling for IEEE 802.16 networks

Includes bibliographical references.The IEEE 802.16 standard introduced as one of the Wireless Metropolitan Area Networks (WMAN) for Broadband Wireless Access (BWA) which is known as Worldwide Interoperability for Microwave Access (WiMAX), provides a solution of broadband connectivity to areas where wired infrastructure is economically and technically infeasible. Apart from the advantage of having high speeds and low costs, IEEE 802.16 has the capability to simultaneously support various service types with required QoS characteristics. ... While IEEE 802.16 standard defines medium access control (MAC) and physical (PHY) layers specification, admission control and packet scheduling mechanisms which are important elements of QoS provisioning are left to vendors to design and implement for service differentiation and QoS support

Quality of Service System Approximation in IP Networks

This paper is sponsored by the Ministry of Education and Research of the Republic of Bulgaria in the framework of project No 105 “Multimedia Packet Switching Networks Planning with Quality of Service and Traffic Management”.This paper presents Quality of Service analyses in wired and wireless IP networks based on the three popular techniques – RSVP, IntServ, and DiffServ. The analyses are based on a quick approximation schema of the traffic system with static and dynamic changes of the system bounds. We offer a simulation approach where a typical leaky bucket model is ap- proximated with a G/D/1/k traffic system with flexible bounds in waiting time, loss and priority. The approach is applied for two cascaded leaky buckets. The derived traffic system is programmed in C++. The simula- tion model is flexible to the dynamic traffic changes and priorities. Student criterion is applied in the simulation program to prove results. The results of the simulation demonstrate the viability of the proposed solution and its applicability for fast system reconfiguration in dynamic environmental circumstances. The simulated services cover a typical range of types of traffic sources like VoIP, LAN emulation and transaction exchange

A Scalable QoS Scheduling Architecture For WiMAX Multi-Hop Relay Networks.

WiMAX Mobile Multi-hop Relay (MMR) network has been introduced to increase the capacity and extend the coverage area of a single WiMAX Base Station (BS) by the use of a Relay Station (RS)