Sheikh Tahir Bakhsh

Indoor positioning in Bluetooth networks using fingerprinting and lateration approach

Global Positioning System (GPS) is a well known navigation system for outdoor applications; however this technology does not work in indoor environments. In order to overcome this limitation, Bluetooth technology can be employed. Furthermore, Bluetooth technology provides an accurate and low cost solution for short range wireless communication. Most of the digital devices provide the Bluetooth functionality which also makes it a good candidate for indoor positioning. In this paper, we use Bluetooth devices for indoor positioning and use signal based parameters such as received power level for position estimation. The accuracy of indoor positioning system is greatly dependant on the parameters selected for estimation and the measurements obtained from the environment. However, the measurements are corrupted by various environmental conditions such as temperature, reflection, presence of obstacles, human body and other communication signals. Therefore, we need to filter the measurements. This paper presents an experimental relationship between the received power level and distance using the standard radio propagation model. The idea behind this study is to provide an accurate distance estimate for Trilateration approach. Based on the experiments performed, the average error is minimized from 5.87 meters to 2.67 meters using gradient filter. The use of gradient filter improves the accuracy by 45 %.

Dynamic Congestion Control through backup relay in Bluetooth scatternet

Bluetooth is a low power wireless technology designed to connect various short-range devices such as laptops, cameras, cell-phones, head-phones, navigators, etc. Bluetooth has limited resources and its devices are connected in ad hoc fashion. The Bluetooth specification allows only eight active devices to communicate within its smallest networking unit known as piconet. Multiple piconets can be connected together through at least one common device, known as relay to form a bigger network called a scatternet. The performance of a scatternet is highly determined by the performance of the relay since it acts as a switch between multiple piconets, where inter-piconet scheduling is the main task to perform. However, the presence of too many relays in the network may cause inefficient use of the limited resources. In contrary, less number of relays may lead to congestion problem because each relay has to participate in multiple piconets and supports several connections. One possible solution is to reorganize the nodes in the scatternet, in order to increase the available bandwidth and to reduce the traffic flows on the congested link. Hence, primarily this paper addresses the issues of traffic congestion on a link by analyzing traffic load in the network. To achieve this, activation of a backup relay is performed by applying role-switching operation, and this technique is called Dynamic Congestion Control (DCC). With DCC, the route length is assured not to increase as to alleviate message and packet overheads in scheduling. The simulation results are evidence that DCC has reduced transmission delays and has increased the scatternet lifetime from 25% to 50% as compared to RVM and LORP techniques.

Dynamic relay management protocol for efficient inter-piconet scheduling in Bluetooth scatternet

Bluetooth is a low power, short range and inexpensive wireless technology that has limited resources. Therefore, the performance of a scatternet is highly dependent on the number of relays and their degree. The existence of unnecessary relays may increase scheduling overhead and consume system resources. In another instance, a large number of links that pass through a single relay may also decrease the system performance. Therefore, an optimum number of relays must be obtained for an efficient scatternet performance, while the system works with limited resources. The dynamic relay management (DRM) protocol is proposed to achieve the said objective and the solutions will be based on relay reduction and load balancing strategies. Through the DRM, a master reduces unnecessary relays to an optimum number and subsequently assigns them the special role as backup relays. In the event when a large number of links pass through a single relay, the master activates one of the backup relays to resolve the bottleneck, by which the load is balanced over a number of relays. Using this relay management technique, analytically the DRM protocol has reduced control overhead from O(n^2) to O(1). Empirically, through simulation of the DRM protocol, the backup relay activation has reduced delay and improved throughput (between 40% and 60%). Also, the simulation results have demonstrated an improvement on network lifetime and packet loss. All these results are evidence that the DRM has outperformed the RVM and LORP protocols for the same issue. Hence, the inefficiency of the inter-piconet scheduling in a scatternet of a Bluetooth network can be resolved by implementing the DRM protocol.

Dynamic Energy-Aware Network Maintenance for Bluetooth

Bluetooth is one of mobile ad hoc network technologies, which allows communication through piconet. A piconet consists of at most eight active devices at the same time. A multiple piconets network is called a scatternet, which is connected through a common node known as a relay. The limited energy available in a Bluetooth-enabled device is a critical issue for the mobile devices to participate effectively in the scatternet. Therefore, to improve the network performance, energy capability of a Bluetooth device should be analyzed periodically, and subsequently to determine its role in the network based on this energy analysis. It is expected that the more energy capable device shall perform more demanding role, i.e. the role of a high performance device shall be selected based on its energy level. In this paper, we discussed the design issues of an efficient Dynamic Energy-Aware Network Maintenance (DENM) technique. The proposed technique dynamically adapts changes in the network and maintains a constructed scatternet, as well as it ensures network stability and reduces overhead. The simulation results showed that the proposed technique outperformed the existing protocols in term of message overhead, transmission delay, and reconstruction time.

Self reorganizing network in Bluetooth scatternet

Bluetooth is playing an important role in communications among electronic devices. Bluetooth communication is possible through piconet, where one device plays master role and other act as slaves. There can be more than one piconet in Bluetooth network, which is called scatternet. Different piconets are connected through a common node called relay. A scatternet may have multiple relays, relay forwards data from one piconet to others. It is observed that needless relays increase packets loss rate and transmission delay due to switching in different piconets. Mobility of relay may cause disconnection of few piconets. In general, scatternet performance can be improved through nodes mobility monitoring. This paper proposes an efficient Self Reorganizing Network Protocol (SRNP) for Bluetooth scatternet. The proposed protocol keeps unnecessary relays information, and assigns them backup relay role. The backup relays are used to rebuild the broken links in scatternet. The simulation results show the proposed protocol reduces message overhead, transmission delay and increases overall network performance.

Dynamic load balancing through backup relay in Bluetooth scatternet

A mobile ad-hoc network (MANET) is a collection of wireless mobile nodes, which creates an infrastructure less temporary network. Bluetooth is a short range, low-cost, low and low power wireless technology. Bluetooth allows communication among electronic devices through its basic network know as piconet. In a piconet one device controls the local network (piconet) know as master and others act as slaves. Multiple piconets may exist in Bluetooth network known as scatternet. The connection among different piconets is provided through a common node known as relay. Relay is connected with more then one master with different hopping pattern relay node forwards data among different piconets. The degree (number of connection) of relay has a serious impact on the network performance. A larger degree of relay increases the packet loss rate and transmission delay. The large degree of relay has to switches among different piconets that increase the scheduling overhead. The paper considers the problem of designing an effective Dynamic Load Balancing (DLB) technique to share the traffic load through Backup Relay (BR). The simulation results show using UCBR and NS-2 the proposed technique avoids bottleneck that reduces the transmission delay, packet loss and increases the throughput plus network lifetime.

Cross-Layer-Based Adaptive Traffic Control Protocol for Bluetooth Wireless Networks

Bluetooth technology is particularly designed for a wireless personal area network that is low cost and less energy consuming. Efficient transmission between different Bluetooth nodes depends on network formation. An inefficient Bluetooth topology may create a bottleneck and a delay in the network when data is routed. To overcome the congestion problem of Bluetooth networks, a Cross-layer-based Adaptive Traffic Control (CATC) protocol is proposed in this paper. The proposed protocol is working on backup device utilization and network restructuring. The proposed CATC is divided into two parts; the first part is based on intra-piconet traffic control, while the second part is based on inter-piconet traffic control. The proposed CATC protocol controls the traffic load on the master node by network restructuring and the traffic load of the bridge node by activating a Fall-Back Bridge (FBB). During the piconet restructuring, the CATC performs the Piconet Formation within Piconet (PFP) and Scatternet Formation within Piconet (SFP). The PFP reconstructs a new piconet in the same piconet for the devices which are directly within the radio range of each other. The SFP reconstructs the scatternet within the same piconet if the nodes are not within the radio range. Simulation results are proof that the proposed CATC improves the overall performance and reduces control overhead in a Bluetooth network.

Dynamic stable relay selection in Bluetooth scatternet

Bluetooth is a progressive technology used for mobile ad-hoc network (MANET) for wireless nodes. Basic network in Bluetooth is called piconet, there could be multiple piconets in Bluetooth that are connected with a common node called relay. Relay plays an important role in the network, because it uses different hopping pattern for different piconets. Relay node has extra responsibility, which is forward data from one piconet to other. The mobility and degree of relay node affects the performance of the network. The problem in ad-hoc network is the node stability and reliability. As in Bluetooth all the communication is synchronized so relay has to switch for communication into different networks, most frequent movement of relay increase control overhead in the network. The mechanism for selection of relay should be simple and effective. A stable node should be selected as relay that increases the reliability and stability of the network. In this paper we consider the problem of designing an efficient mobility based relay selection and unnecessary relay role switched to slave. Our proposed scheme reduces the delay, message overhead, control overhead, and increases the network stability and reliability. Performance results reveal that our proposed scheme significantly improves the performance of the network.