New Bluetooth scatternet concept
The emergence of Bluetooth as a wireless network solution assists in bringing together multiple technologies in different sectors and provides rapid interconnections to form a network paradigm. Typically, up to 8 Bluetooth devices can form a centralized network, called a piconet, controlled by a master node, which allocates transmission slots to all other nodes (slaves) in the piconet. However, the structure of inter-piconet connection: called the scatternet is not defined in the Bluetooth Specification. To develop a new scatternet structure, many challenges such as topology formation, intra and inter-piconet scheduling and packet routing are considered. The thesis addresses these critical issues based on the scatternet formation using Bluetooth. The scatternet, presented in this thesis, employs a tree hierarchy structure formation with a Leader root of three hierarchies. Within the scatternet, the new concept exploits clock and frequency synchronization for all new piconets creation. This synchronization prevents interferences and the need for guard time while switching piconet. Thus enabling a device to switch from one piconet to another at every slot. Furthermore, an innovative intra-piconet design is proposed to improve QoS within Bluetooth piconet. By exploiting the device queue status, the scheme defines a predictable polled sequence, and an adaptive traffic allocation. This offers a better fairness, and a significant power reduction when compared to the conventional Round Robin scheme. Moreover, with the perfect scatternet synchronization, the devices switch to other piconets to transmit data and, within one slot time, return to the initial piconet before the next predicted poll time exchange occurs. This considerably improves the traffic data transfer, especially for a significant number of devices present within the area. In addition, a new routing process is developed in this thesis, which facilitates communication within the scatternet. From the scatternet tree hierarchy position, a new addressing node routing is proposed to keep the overhead network low, and guarantees that any packet forwarded reaches its destination. The performance of the new scatternet is evaluated for each scatternet phase, through a Matlab simulation program, and the significant improvement of Bluetooth QoS achieved through the proposed approach is fully demonstrated. This thesis also presents a primary implementation of the scatternet concept using a dedicated Bluetooth hardware system.