Mazen G. Khair

Power saving clusters for energy-efficient design of fiber-wireless access networks

Wireless and optical broadband access technologies are foreseen to converge by combining the high transmission capacity of the optical communications with the flexibility and the ubiquitous nature of the wireless communications in order to satisfy the growing end-user demand for bandwidth. This hybrid technology eliminates the cost of running fiber to the destination by allowing the fiber deployment until a certain point from where wireless base stations take over to provide service to the end-user. Despite handling the growing end-user demand, new telecommunication technologies are required to be energy efficient. Recently, there is an increasing interest to reduce the energy consumption of the Information and Communications Technology (ICT) sector and the ICT related CO2 emissions. In this paper, we propose an energy efficient design scheme for a fiber-wireless network consisting of a WDM-PON in the optical back-end and a 4G broadband access technology-enabled wireless front-end, e.g. Long-Term Evolution (LTE) or WIMAX. The proposed design scheme uses the average load profiles on the WDM-PON segments and attempts to form power saving clusters (PSCs) which are fiber rings interconnecting several hybrid (fiber-wireless) access networks. Each PSC enables one or more OLTs to sleep and distributes the backlogged traffic among the active segments in the ring. The proposed scheme aims to maximize the number of sleeping segments, and consequently maximize the power saving. Through simulations, we show that the proposed scheme leads to a power saving between 20% and 45% with a maximum of 3.5% increase in the fiber deployment cost by running the interconnection fibers to form PSCs.

Secured distributed discovery services in the EPCglobal network

The EPCglobal Network is a global network developed to ensure global interoperability between trading partners in supply chains. Its main goal consists of providing real-time and accurate traceability of items in the supply chains. One of the major building blocks of the EPCglobal Network is the Object Naming Service (ONS) which is a central lookup service used mainly to locate the EPC manager information sources of a given EPC. Discovery services refer to a suite of services enabling any user, subject to authentication, to retrieve all relevant data, subject to access control policies, related to a given EPC in the EPCglobal Network. Many promising DHT-based distributed and secure architectures have been proposed to make the ONS more scalable and more secure than the current ONS specifications. Some of them focused on improving a specific aspect of the existing ONS architecture while others suggested integrated solutions for various weaknesses of the current ONS system. In this paper, we present a DHT-based, scalable and secure architecture for data lookup in the EPCglobal Network. The proposed architecture aims at replacing the current ONS system with a secure distributed Discovery Services system.

Optimization for Fault Localization in All-Optical Networks

Fault localization is a critical issue in all-optical networks. The limited-perimeter vector matching (LVM) protocol is a novel fault-localization protocol proposed for localizing single-link failures in all-optical networks. In this paper, we study the optimization problems in applying the LVM protocol in static all- optical networks. We consider two optimization problems: one is to optimize the traffic distribution so that the fault-localization probability in terms of the number of localized links is maximized, and the other is to optimize the traffic distribution so that the time for localizing a failed link is minimized. We formulate the two problems into an integer linear programming problem, respectively, and use the CPLEX optimization tool to solve the formulated problems. We show that by optimizing the traffic distribution the fault-localization probability can be maximized and the fault-localization time can be minimized. Moreover, a heuristic algorithm is proposed to evaluate the optimization results through simulation experiments.

Cellular IP address provisioning in a heterogeneous wireless network

SUMMARY In this article, we propose a dynamic Internet Protocol (IP) address assignment architecture for heterogeneous wireless IP devices network. The IP device could be a sensor device, a laptop, a cell phone, or any wireless device using IP communications. The proposed architecture introduces security and service reliability to the consumer while reducing the operational expenditure for the service providers. According to the proposed scheme, each node maintains an IP address pool storing the current occupancy of each IP address. Each node advertises its database whenever the ratio of negative acknowledgments from the domain name server to the total number of requests at a given node exceeds a certain threshold. We evaluate our IP assignment scheme under two traffic intensity scenarios, namely the uniform traffic intensity and the heterogeneous traffic intensity. Performance evaluation is carried out with respect to blocking probability and average IP list utilization. We define three types of blocking probability for the user requests as follows: The real blocking, the unjustified acceptance, and the unjustified rejection. We observe that the proposed scheme outperforms the uniform assignment as long as the threshold is below 1.5% for the uniform intensity scenario and 1% for the heterogeneous scenario. Furthermore, this architecture considers the security aspect of the wireless network by allowing only registered devices to communicate with other registered devices. Copyright

Distributed discovery services via EPC-BGP for mobile RFID

In this paper, we propose an extended architecture of the EPCglobal network that allows tracking objects. This architecture makes use of the distributed discovery services along with the EPC-BGP to provide detailed information about an object regardless of its location. In the EPCglobal network, each object is assigned an IPv6 address once it leaves the last gateway in the supply chain. The IP address of the last gateway enables backtracking of all the information about this object throughout the supply chain. To this end, EPC status updates are crucial in order to advertise any changes in the EPC into the supply chain. On the other hand, concurrent EPC updates, expired EPC databases and/or limitation of resources may cause blocking of an EPC update request. Therefore, we evaluate our proposed architecture in terms of blocking probability of the EPC update requests. To this end, We define three types of blocking, namely the Justified Update Blocking (JUB), Unjustified Update Acceptance (UUA), and Unjustified Update Blocking (UUB). We investigate the impact of the frequency of update advertisements on the blocking probability. Numerical results confirm the trade-off between blocking probability and communication/computation overhead due to EPC update messages. However, further investigation in terms of the number of advertisements and the distance between the routing tables confirms that advertisement of EPC update messages based on certain thresholds can overcome this trade-off.

Towards cellular IP address assignment in wireless heterogeneous sensor networks

In this paper, we have proposed a dynamic IP address assignment architecture for wireless heterogeneous sensor networks. The assignment scheme and the architecture guarantee that communication channels can be assigned only between the registered devices ensuring the security. The dynamic IP address assignment scheme is based on the advertisement of the IP address utilization status at the base stations. Thus, each base station advertises its IP address utilization database when the ratio of the negative acknowledgement messages received from the DNS exceeds a certain threshold. By simulations, we have shown that the proposed assignment scheme introduces significant enhancement in terms of blocking probability when compared to an approach where each base station has its own IP address pool. Furthermore, we have defined three types of blocking, the real blocking, the unjustified acceptance and the unjustified rejections. We have seen that the proposed scheme can lead to lower blocking probability compared to the uniform IP assignment as long as the update threshold is kept below 1.5%.

Heterogeneous Clustering Of Sensor Network

Abstract In this paper, we proposed a heterogeneous clustering of sensor network in which different types of sensors exist that report to different sinks. This heterogeneous clustering approach has its own security measures in which only registered devices in the IP-DNS can be part of the heterogeneous clustering network and can set up communication channel with the sink or with any other device. We have also proposed a dynamic hierarchical clustering scheme in which certain number of sensor nodes that locates in specific area will be grouped as cluster and nominate a cluster head of their own. We have proposed two cluster head selection criteria. The fist one is edge sensors in which sensors that are closer to other clusters will be selected as cluster head whereas the second select the cluster head that has the minimum average hop distance to other sensors. We have seen that the second selection criteria leads to shorter path as the cluster heads are in the middle of cluster and closer to other nodes. We have compared our proposed architecture with other well known on demand routing protocol named as AODV and we have seen that our approach perform way better in terms of delay. Our approach can allow the usage of proactive protocols at each routing level and still have limited size of routing table at each node. The only trade off is that our approach has slightly longer path length compared to AODV. Furthermore, we proposed a hierarchical routing scheme in which sensor networks at each routing level is grouped and exchange routing information among themselves avoiding flooding the network with control over head messages.

Connection provisioning constrained to fault localization in all-optical networks

Fault localization is becoming a critical issue in all-optical networks. The Limited Perimeter Vector Matching (LVM) protocol is a novel fault localization protocol for localizing single-link failures in all-optical networks. In this paper, we study the fault localization optimization problem by applying the LVM protocol where the traffic demands (or lightpath requests) are known a priori. Given the traffic demands, the fault localization optimization problem aims to optimize the traffic distribution so that the fault localization probability in terms of the number of localized links can be maximized. Moreover, the solution to the problem can also provide the maximum number of wavelengths needed on each link to obtain the maximum fault localization probability.

Optimization for minimizing fault localization time in all-optical networks

The limited perimeter vector matching (LVM) protocol is a novel fault localization protocol for localizing single-link failures in all-optical networks. In this paper, we study the optimization problem to minimize fault localization time when applying the LVM protocol to static all-optical networks, where traffic demands (or lightpath requests) are known a priori. Given the traffic demands, the optimization problem is to find a traffic distribution so that the time for localizing a failed link can be minimized. We formulate the problem into an integer linear programming problem and use CPLEX to solve the problem. We show through numerical results that by optimizing the traffic distribution the fault localization time can be effectively minimized and is below the OSPF localization time (40 msec) in traditional IP networks.

Decentralized RFID coverage algorithms using writeable tags

A Radio Frequency IDentification (RFID) reader network is as a collaboration of RFID readers that aim to cover (i.e., identify, monitor, and track) every RFID tag in a given area. The RFID coverage (RFC) problem is defined as follows. Given a reader network, assign to each tag t a specific reader v in its proximity such that v is responsible for covering t (called its owner), while minimizing the number of owner readers. The problem has applications in energy conservation and in eliminating readers and data redundancy from the reader networks. We introduce a number of decentralized algorithms for the RFID coverage problem: 1) algorithms RANDOM, RANDOM+, and MAX-MIN which are randomized algorithms that run in O(1) write/read rounds, 2) algorithm GDE which is an efficient decentralized implementation of the greedy set cover algorithm, and 3) an improvement of GDE which is called . Our algorithms assume that the RFID tags are writeable, where a writeable tag is a passive RFID tag with writeable memory. We show using simulation experiments that our algorithms outperform major RFID coverage algorithms in various scenarios with respect to a number of performance metrics.