Tuesday, 11 November 2008

Design Integration with Ad Hoc Networks

The main disadvantage of WCDMA networks is perhaps on the limited bandwidth available to the users. The emerging multimedia applications (e.g., streaming for high-quality HDTV video) demands high throughput. Therefore, further integration with WLAN and ad hoc networks provides the unique opportunity to connect every user/device with high bandwidth. The primary advantage is the 11-/45-Mbps bandwidth offered by 802.11b/a/g WLAN (infrastructure mode) and perhaps even higher bandwidth for the ad hoc and personal area networks (PAN) networks.
How to integrate these three networks together into a highly efficient and seamless network requires systematic investigation in the future. One typical approach is to have a hierarchical design with the combined WCDMA/WLAN/ad hoc serves as the top–down structure. The integration of WCDMA/WLAN requires the intelligent selection of gateway points in either the WLAN portion or the 3G network to connect the users to the WCDMA core network anywhere.
There are a few schemes83–86 proposed in recent years for such an effort. However, the majority of these schemes assumed that the bandwidth for the 3G core networks will be increased significantly in the near future.
We believe it will take a longer time for WAN/MAN such as WCDMA to deliver high-bandwidth throughput. On the other hand, WLAN and ad hoc networks will have much faster development on delivering high-throughput
products. Thus, our approach87 uses WLAN to cluster mobile users and reduce the 3G radio activity. The philosophy is that when the 3G radio link is less crowded, it most likely provides higher efficiency for the users. Based on the relative BS/AP positions of the WCDMA and WLAN networks, we analyzed six cases of configurations. These six cases cover the majority of scenarios when WCDMA’s BS interacts with WLAN’s APs. We have formulated the problem, and produced the suboptimal solutions to reduce the overall interference between these devices.
When many users connect to a single AP of WLAN, the load imbalance becomes apparent. Ad hoc networks can be jointly integrated between WLAN/ad hoc as the relay points to achieve better load balance. Since ad hoc networks mostly work within a limited distance (e.g., within tens of meters), it is natural to have PANs connected with the combined WCDMA/WLAN networks to extend the global connectivity. One approach to integrate ad hoc networks into the combined WCDMA/WLAN networks is to follow the top–down structure, which only allows the ad hoc networks connect to WLAN only (instead of providing connectivity to the WCDMA core networks, though it is possible). However,
even with this simplified structure division, the overall design task still remains to be a challenge. The key factor is, with the ad hoc networks, relay can be mobile. Though the AP’s location is fixed, it is open to decide which mobile station should serve as the relay point to connect to the AP on behalf of other mobile stations of the same ad hoc networks. Therefore, a higher complexity of overall system design should be addressed. These issues include what
media access methods should the system provide to support different traffic types and what relay structure should be determined with the goal to maximize the overall throughput.

Reference:Wireless Ad hoc Networking by Shih-Lin Wu & Yu-Chee Tseng

Wireless Ad Hoc Networking
Author:Chang Guang University, Tao-Yuan, Taiwan National Chiao-Tung University, Hsin-Chu, Taiwan
Reader Reviews

What a Techie needs to Understand wireless5
Wireless Ad Hoc Networking: Personal-Area, Local-Area, and the Sensory-Area Networks by Shih-Lin Wu and Yu-Chee Tseng (Wireless Networks and Mobile Communications: Auerbach) The rapid progress of mobile, wireless communication and embedded micro-sensing MEMS technologies has brought about the rise of pervasive computing. Wireless local-area networks (WLANs) and wireless personal-area networks (WPANs) are now common tools for many people, and it is predicted that wearable sensor networks will greatly improve everyday life as we know it.
By integrating these technologies into a pervasive system, we can access information and use computing resources anytime, anywhere, and with any device. Wireless Ad Hoc Networking: Personal-Area, Local-Area, and the Sensory-Area Networks covers these key technologies used in wireless ad hoc networks. The book is divided into three parts, each providing self-contained chapters written by international experts. Topics include networking architectures and protocols, cross-layer architectures, localization and location tracking, time synchronization, QoS and real-time, security and dependability, applications, modeling and performance evaluation, implementation and experience, and much more.
The book is novel in its single source presentation of ad hoc networking and its key technologies and applications over the platforms of personal-area, sensory-area, and local-area networks. It is a valuable resource for those who work in or are interested in learning about the pervasive computing environment.
* Covers key technologies in wireless and ad hoc networks for personal-area, local-area, and sensory-area networks
* Presents state-of-the-art research and developments by an international team of experts
* Explores topics from networking architectures and protocols to implementation experience and measurements

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