A novel push-and-pull hybrid data broadcast scheme for wireless information networks

A new push-and-pull hybrid data broadcast scheme is proposed for providing wireless information services to three types of clients, general, pull and priority clients. Only pull and priority clients have the back channel for sending requests to the broadcast server. There is no scalability problem with the hybrid scheme because the amount of pull and priority clients is very small. Based on the requests collected from pull and priority clients, the server estimates the interest pattern changes of the whole client population. Then the broadcast schedule on the push channel for the next broadcast cycle is adjusted. Besides the push channel, a small amount of broadcast bandwidth is allocated to a pull channel. The data to be broadcast on the pull channel is decided by the server in real-time and priority is given to requests from priority clients. Simulations show that with a time-varying client interest pattern, the average data access time for all three types of clients can be minimized. Because of the priority in using the pull channel, priority clients can achieve the lowest access time and pull clients can achieve a lower access time than general clients. To further improve the performance, the hybrid scheme with local client cache is also investigated.published_or_final_versio

Improving the Performance of the Wireless Data Broadcast by the Cyclic Indexing Schemes

Abstract. Wireless data broadcast is an effective approach to disseminate information to a massive number of users. Indexing techniques for broadcasting data can reduce the battery power consumptions of mobile terminals by decreasing the tuning time. The organization of the indexes affects the efficiency of data searching. We investigate how the degree of the index node affects the tuning time, and thus minimize the power c o n s u mp t i o n o f u s e r ' s terminals. We proposed a performance measurement for the tuning time and a cyclic indexing algorithm. The numerical results suggest the degree of an index node be 3 when the access probabilities of the data tend to be uniformly distributed so that the expected tuning time is minimal. When the access distribution of the data nodes is skewer, the tuning time can be minimized by setting the degree in the index node 2

A Broadcast Disk scheme for mobile information system

The rapidly expanding technology of cellular communications, wireless local area network (LAN), wireless data networks and satellite gives mobile users the ability of accessing information anywhere and anytime. Data broadcasting algorithm plays an important role as it instructs the server to disseminate large amount of data at a fast rate to many mobile clients. One of the work known as the Broadcast Disk method creates a sequence of slots containing data and broadcasts them in a circular manner on the air. Mobile clients keep listening to the air and catch those slots that interest them. However in the Broadcast Disk method, some slots are empty, which results to waste of resources and increase in clients' average waiting time. Empty slots are randomly generated and difficult to be located. In this paper we present a scheme called the Optimum Broadcast Disk, which is an enhancement of the Broadcast Disk method to overcome the empty slots issue and hence reduce the users' waiting time. We manage to locate these empty slots and fill them with popular data. We demonstrate by case studies and simulation that our scheme eliminates empty slots and minimizes clients' average waiting time.Facultad de Informátic

Performance Analysis of Wireless Networks with QoS Adaptations

The explosive demand for multimedia and fast transmission of continuous media on wireless networks means the simultaneous existence of traffic requiring different qualities of service (QoS). In this thesis, several efficient algorithms have been developed which offer several QoS to the end-user. We first look at a request TDMA/CDMA protocol for supporting wireless multimedia traffic, where CDMA is laid over TDMA. Then we look at a hybrid push-pull algorithm for wireless networks, and present a generalized performance analysis of the proposed protocol. Some of the QoS factors considered include customer retrial rates due to user impatience and system timeouts and different levels of priority and weights for mobile hosts. We have also looked at how customer impatience and system timeouts affect the QoS provided by several queuing and scheduling schemes such as FIFO, priority, weighted fair queuing, and the application of the stretch-optimal algorithm to scheduling