Saad Ahmad Khan

Performance analysis of a Zigbee beacon enabled cluster tree network

Zigbee provides a realistic and feasible solution for the implementation of ‘low data rate’, ‘low cost’ and ‘minimum energy consumption’ networks. These attractive features are compelling the industry to adopt Zigbee and deploy and integrate it in a whole slew of consumer market applications. Energy consumption always plays a critical role in modern system design and coerces developers to propose and exploit various routing techniques to minimize power losses. The IEEE 802.15.4 standard has been made use of for the MAC and physical layers of the Zigbee protocol stack. In our work we have identified that a clustered network approach brings about minimum energy consumption in such networks; this is owes to the fact of load distribution among data aggregating heads. We provide a beacon enabled performance analysis of such network. The impact of Zigbees deployment has been felt in e.g. the health care industry, patient monitoring, home are networks, remote surveillance and management and consumer wireless devices such as cell phones, PDAs, etc. We expect our findings to aid in developers in engineering systems in the aforementioned applications; in such a manner that Zigbees integration would result in networks that consume minimal energy, thereby, conserving energy and ensuring maximal longevity of the network and its devices.

Routing towards a mobile sink using virtual coordinates in a wireless sensor network

Geographical routing can provide significant advantages in wireless sensor networks. However in many sensor networks, it is difficult or costly to find the exact location of the nodes. The virtual coordinate techniques allow a network to acquire a coordinate system without relying on geographical location. In this paper, we describe MS-DVCR, an extension of a state-of-the-art virtual coordinate routing protocol (DVCR) with the ability to route towards a mobile sink. We describe the design principles and implementation of the proposed protocol and through an experimental study, we show that it matches the performance of a simple extension of DVCR for mobile sinks while providing a significantly lower energy consumption.

Bridge protection algorithms - A technique for fault-tolerance in sensor networks

Sensor networks operating in the field might be subject to catastrophic events which destroy a large number of nodes in the geographic area. Often, the aftermath of such an event is the creation of a network of bridged fragments where connectivity is maintained by one or several bridge nodes. These networks are vulnerable, because the bridge nodes will soon exhaust their energy resources leading to the fragmentation of the network. This paper describes a bridge protection algorithm (BPA), a combination of techniques which, in response to a catastrophic event, change the behavior of a set of topologically important nodes in the network. These techniques protect the bridge node by letting some nodes take over some of the responsibilities of the sink. At the same time, they relieve some other overwhelmed nodes and prevent the apparition of additional bridge nodes. To achieve this, the algorithm sacrifices the length of some routes in order to distribute routes away from critical areas. In a variation on the BPA algorithm, we show that if geographic information about the nodes is available, replacing shortest path routing with a routing model which follows the edges of the relational neighborhood graph will lead to further improvements in the expected connected lifetime of the network.

Greedy path planning for maximizing value of information in underwater sensor networks

Underwater sensor networks (UWSNs) face specific challenges due to the transmission properties in the underwater environment. Radio waves propagate only for short distances under water, and acoustic transmissions have limited data rate and relatively high latency. One of the possible solutions to these challenges involves the use of autonomous underwater vehicles (AUVs) to visit and offload data from the individual sensor nodes. We consider an underwater sensor network visually monitoring an offshore oil platform for hazards such as oil spills from pipes and blowups. To each observation chunk (image or video) we attach a numerical value of information (VoI). This value monotonically decreases in time with a speeed which depends on the urgency of the captured data. An AUV visits different nodes along a specific path and collects data to be transmitted to the customer. Our objective is to develop path planners for the movement of the AUV which maximizes the total VoI collected. We consider three different path planners: the lawn mower path planner (LPP), the greedy planner (GPP) and the random planner (RPP). In a simulation study we compare the total VoI collected by these algorithms and show that the GPP outperforms the other two proposed algorithms on the studied scenarios.

Zigbee Based Reconfigurable Clustered Home Area Network

Zigbee technology is here to stay. With current market trends it is to be understood that it will play a vital and major role in low rate wireless personal area networks. Zigbee networks facilitate numerous applications such as consumer electronics, home area networks, health care monitoring and environmental monitoring. Effective routing in wireless sensor networks is critical to conserve energy resources for the longevity of the network. In this paper we propose energy efficient cluster tree architecture for home area network. The reconfigurable architecture improves the Zigbee network performance by distributing equivalent load among its data fusing heads on basis of leftover energy. Simulations show that using such self organizing cluster tree topology is most effective in terms of energy consumption as compared to simple Zigbee mesh networks.

Clustered home area network: A beacon enabled IEEE 802.15.4 approach

Driven by emerging standards, increasing energy costs, and advances in Wireless Sensor Networking, the ldquosmart homerdquo is becoming a reality for the mass market. Over a decade, professional installers have been using proprietary systems, with emergence of standards such as Zigbee, cost effective low-data rate, home solutions are now realizable. This paper presents a cluster based home area network in which Zigbee has been used as the underlying technology. Our paper focuses on analysis of power consumption of Zigbee based networks for low data rate applications like simple HANs. Our work is a dedicated effort on network and application layer. The use of beacon mode and hierarchical clustered mechanism is suggested. Power consumption and performance analysis have been done and results have been shown to validate the analysis.

Scheduling multiple mobile sinks in Underwater Sensor Networks

Underwater Sensor Networks (UWSNs) provide valuable data for research studies and underwater monitoring and protection. UWSNs need to overcome the handicap that high data rate wireless transmissions are not available underwater. Acoustic communications are used as a medium but they are only good for transmitting e.g. signalling information. Autonomous Underwater Vehicles (AUVs) can serve as mobile sinks that gather and deliver larger amounts of data from the underwater sensor network nodes. Value of Information (VoI) is a data tag that encodes the importance and time-based-relevance of a data chunk residing at a sensor node. VoI, therefore, can serve as a heuristic for path planning and prioritizing data retrieval from nodes. The novelty of this paper lies in providing algorithms which schedule multiple mobile sinks (AUVs) for data retrieval from nodes while maximizing the retrieved VoI. The class of algorithms discussed are based on greedy heuristics.

Proactive multipath data dissemination for Multimedia Sensor Networks

Sophistication and refinement of technology has led to the development of Wireless Sensor Networks (WSNs). Video sensors are actively used in WSNs to increase their event description power. Wireless Multimedia Sensor Networks (WMSNs) have been deployed in numerous applications e.g. environmental monitoring, advanced health care delivery, industrial process control and disaster relief operations. WMSNs have limited transmission capacity and delivery of multimedia content using single path routing introduces large delays. This has motivated the research community to develop multi-path routing schemes that efficiently transmit multimedia content while maintaining delay constraints. Most of these approaches require each sensor nodes to have information of their geographic co-ordinates, along with co-ordinates of their neighbors and destination. In this paper we present a novel disjoint multi-path routing scheme that does not require any information of geographical coordinates. This scheme explores energy efficient, minimum hop delay disjointed paths between video sensor and base-station to support multiple routes. Performance evaluation of the our proposed scheme is performed in various network environments. It is observed that our scheme surpasses simple disjoint multi-path schemes and results in considerable energy saving in all network deployment models under consideration.

Circular Update Directional Virtual Coordinate Routing Protocol in Sensor Networks

In a wireless sensor network, virtual coordinates provide most of the advantages of geographic routing strategies without actually relying on the location information of the nodes. Using a mobile sink provides advantages such as distributing energy consumption throughout the network. However, nodes need to be updated about the new virtual coordinate of the mobile sink as it moves. In this paper, we propose Circular Update-Directional Virtual Coordinate Routing (CU-DVCR), an algorithm specialized in routing towards a mobile sink in virtual coordinates. Through a set of experimental studies we show that CU-DVCR consumes less energy compared to alternative algorithms while providing comparable performance.

Optimizing Resurfacing Schedules to Maximize Value of Information in UWSNs

In Underwater Sensor Networks (UWSNs) with high volume of data recording activity, a mobile sink such as a Autonomous Underwater Vehicle (AUV) can be used to offload data from the sensor nodes. When the AUV approaches the underwater node, it can use high data rate optical communication. However, the data is not considered delivered when it was transferred from the sensor node to the AUV, but when the AUV had resurfaced and transferred the data to the sink. If the data is not time sensitive, it is sufficient for the AUV to resurface only once at the end of its data collection path. However, for time-sensitive data, it is more advantageous for the AUV to resurface multiple times during its path, and upload the data collected since the previous resurfacing. Thus, a resurfacing schedule needs to complement the path planning process. In this paper we are using the metric of Value of Information (VoI) as the optimization criteria to capture the time- sensitive nature of collected information. We propose a genetic algorithm based approach to determine the resurfacing schedule for an AUV which is already provided with the sequence of nodes to be visited.