Rashid A. Saeed

Dynamic packet beaconing for GPSR mobile ad hoc position-based routing protocol using fuzzy logic

Greedy perimeter stateless routing (GPSR) is a well-known position-based routing protocol in mobile ad hoc network (MANET). In GPSR, nodes use periodic beaconing (PB) strategy in broadcasting beacon packets to maintain up-to-date information on the geographical position of their neighbor nodes within their transmission boundary range. The nodes that receive beacon packets save all known neighbor nodes, along with their geographical position information, in their neighbor list to make effective routing decisions. Most recent studies on position-based routing protocols assume that the position information in the neighbor list of a node is accurate, although only a rough estimate of such position information is actually available to the node. Node mobility causes frequent network topology changes in MANETs. Thus, neighbor-to-neighbor relationships change frequently. Using the PB strategy leads to inaccurate node position information in the neighbor list of a node. In addition, it may cause the routing protocol to make suboptimal decisions and not route packets through the best-located neighbor within the transmission range of the node. This study presents an analysis of the influence of position information inaccuracy caused by network parameters such as beacon packet interval time (BPIT) and node moving speed (NMS) on the performance of GPSR position-based routing protocols. To overcome the effect of position information inaccuracy in the neighbor list of a node, we proposed a fuzzy logic dynamic beaconing (FLDB) strategy to improve the reliability of the neighbor list of a node by optimizing time between transmissions of beacon packets in position-based routing protocols. Optimization is based on the correlation between NMS, number of neighboring nodes (NoNNs) and BPIT using fuzzy logic control (FLC) mechanism. The simulation experiment shows the effectiveness of the FLC mechanism in improving overall performance of GPSR position-based routing protocol in terms of beacon packet control overhead, end-to-end delay, non-optimal hop, and false node position.

Design and evaluation of lightweight IEEE 802.11p-based TDMA MAC method for road side -to-vehicle communications

Wireless vehicular communications (WVC) has been identified as a key technology for intelligent transportation systems (ITS) for a few years ago. IEEE 802.11p is the proposed standard for physical and MAC layer of WVC devices. The main objective of the standard is to change the frame format and increase delay spread tolerance introduced by vehicle mobility, in which the channel bandwidth is scaled from 20 MHz i.e.802.11a to 10 MHz i.e. 802.11p. This paper proposes TDMA technique with fixed time slots and guard band between slots to ensure interoperability between wireless devices communicate in rapidly changing environment where transactions must be completed in small timeframe. The new TDMA sub-layer is proposed to be on-top of the conventional 802.11p MAC. The simulation results present the performance analysis and validate the efficiency of the proposed scheme.

Femtocell Communications and Technologies: Business Opportunities and Deployment Challenges

Femtocell is currently the most promising technology for supporting the increasing demand of data traffic in wireless networks. Femtocells provide an opportunity for enabling innovative mobile applications and services in home and office environments. Femtocell Communications and Technologies: Business Opportunities and Deployment Challenges is an extensive and thoroughly revised version of a collection of review and research based chapters on femtocell technology. This work focuses on mobility and security in femtocell, cognitive femtocell, and standardization and deployment scenarios. Several crucial topics addressed in this book are interference mitigation techniques, network integration option, cognitive optimization, and economic incentives to install femtocells that may have a larger impact on their ultimate success. The book is optimized for use by graduate researchers who are familiar with the fundamentals of wireless communication and cellular concepts.

Macro mobility scheme in NEMO to support seamless handoff

In order for the mobile networks to stay connected to the Internet, Network Mobility (NEMO) is involved with the management of the different types of movements by mobile routers during rapid changes of the Point of Attachment (PoA). Accordingly to achieve seamless handoff with lower delay and packet loss in NEMO environment, it is very important to get better performance of mobility management protocol. As the main idea of Network Mobility Basic Support Protocol (NEMO BSP) is to create bi-directional tunnel between the Serving Mobile Routers (SMR) with its Home Agent (HA) and perform the handoff after complete layer 2 switching. Therefore, it should limit frequent registrations of Mobile Network Nodes (MNNs) with their HAs. Furthermore, creating bi-directional tunnel between MR and its HA for all communications makes sub-optimal problem, in which all the packets are tunneled and encapsulated via HA of the Serving MR. This increases handoff delay, packet loss and disconnections probability. To overcome handoff related problems, the Fast Hierarchical Mobile IPv6 (FHMIPv6) works as a solution for host mobility. However, in nested NEMO environment applying improved FHMIPv6 mechanism is a challenging task since consideration has to be given to both MR and its MNNs as well. This paper proposed macro mobility scheme in order to achieve seamless handoff through modification of signaling messages. Additionally, location update cost is calculated and compared with NEMO BSP via analytical approach. The analytical result shows that the location update cost for the proposed scheme is about 69 % less than that of NEMO-BSP.

Cluster-based multi-hop vehicular communication with multi-metric optimization

Dead spot and out of coverage problem are serious problems especially in the rural and suburban areas where the network infrastructure is not deployed. In this paper, a new end to end multi hop relay scheme for vehicular communication is proposed to extend the coverage or/and relaxing frequent handoff process. The scheme allows vehicles to continue connected to infrastructure network i.e. UMTS. Relay discovery, relay selection and gateway selection are discussed and examined. The proposed scheme can be implemented on top of any VANET routing protocols. AODV and DSDV were used as underlying protocol to evaluate our scheme. An integrated simulation environment combined of VanetMobiSim and NS2 is used to simulate our proposed scheme. The simplified gateway selection shows the best performance on top of AODV compare to DSDV.

An investigation of femtocell network synchronization

Currently, Femtocell technology emerged for cellular wireless networks, which has rapidly engrossed cellular industry. The principle of femtocell to the mobile operators is to reduce cost and improve signal quality in indoor coverage which is also considered a possible path to the fixed-mobile convergence (FMC) goal. Femtocell extends network coverage and delivers high-quality mobile services inside residential and business buildings through broadband network, i.e. ADSL. Femtocell access point (FAP) or home base station (HBS) intends to serve small number of users, i.e. 4 users and covers about 30 meter square similar to existing WiFi access points. However, femtocell introduces new challenges to the telecom industries in terms of handoff between femto and macrocells, interference management, localization and synchronization. Among all of these challenges, synchronization is considered corner stone for proper working for femtocell. The problematic issue in femtocell synchronization is that all the data and control traffics travel through IP broadband network. The IP broadband network is usually owned and managed by third party and not by the mobile operator, which is complicated the synchronization. Unsynchronized FAPs may cause harm interferences and wrong handover dictions. In this study we investigate and overview the current femtocell synchronization techniques and compare between them. Possible improvements and recommendation for each method is identified. Proposed schemes and indicated future research areas are also discussed.

The challenges of wireless internet access in vehicular environments

The economics of currently available broadband access technologies motivate for innovate and deploy new system designs and applications in vehicular communication. The widely available and flexible Wi-Fi technique meets the cost and suitability targets for vehicular applications. To cope with the special requirements of vehicular, amendments of 802.11 standards at the MAC and PHY protocol level has been introduced in IEEE802.11p. IEEE 802.11p is the proposed standard for physical and MAC layer of wireless access in vehicular environment (WAVE) devices. The main objective of the new standard is to amend 802.to support vehicle mobility up to 150km/hr and distance 1000km by changing the frame format and increase delay spread tolerance introduced, in which the channel bandwidth is scaled from 20 MHz in 802.11a to 10 MHz in 802.11p. This paper reviews the challenges of wireless internet connectivity in vehicular communication. Transmission range, data handover and security are also covered in the paper. Other related works is reviewed and analyzed as well.

Review: Evaluation of MANEMO route optimization schemes

In the doorway of the Mobile IPv6 (MIPv6), it was considered as the standard protocol that support the host mobility. Due to its limitation that does not support the mobile routers (MRs), the Internet engineering task force (IETF) has introduced the NEMO basic support (NEMO BS) protocol. The mobile ad hoc network (MANET) routing protocol provides the local and the direct communications between two mobile devices within the nested NEMO (when multiple MRs are connected together). Integrating the MANET and the NEMO (MANEMO) provides the necessary additions to the existing protocols (IPv6, neighbor discovery (ND), and NEMO) to support the nested MRs. It provides a mechanism to select the most suitable path to the Exit Router (ER) as a default in the MANEMO Fringe Stub (MFS). The NCM (NEMO centric MANEMO) protocol is introduced to address the nested NEMO issues (e.g. pinball problem) by using the MANET routing a protocol (i.e., OLSR), while the MCM (MANET centric MANEMO) protocol is introduced to address the MANET problem (e.g. Internet connectivity). The main aim of this paper is to investigate the current approaches that are introduced to provide the route optimization (RO) for the NEMO. It highlights the strengths and the limitations of these approaches. Both the qualitative and the quantitative evolutions of these proposals are hereby presented.

An enhanced hybrid wireless mesh protocol (E-HWMP) protocol for multihop vehicular communications

Integration of Vehicular Ad-hoc Network (VANET) and Universal Mobile Telecommunication System (UMTS) is a promising architecture for future machine-to-machine applications. This integration helps the vehicles have steady Internet connection through UMTS network and at the same time can communicate with other vehicles. However, the dead spot areas and unsuccessfully handoff processes due to the high speed of the vehicles can disrupt the implementation of this kind of architecture. In this paper, a new Simplified Gateway Selection (SGS) scheme for multihop relay in VANET-UMTS integration network is proposed. The main aim of this research is to enhance the integration between VANET and UMTS network, and extend the coverage in the area where there is no coverage, and reduce the amount of overhead, and reduce delay metrics, and increasing the packet delivery ratio, and also to reduce the dead spot in VANET-UMTS network. An enhanced version of HWMP is a combination of IEEE802.11p and IEEE802.11s for multihop vehicular communications is proposed. An integrated simulation environment combined of VanetMobiSim and NS2 is used to simulate and evaluate the proposed scheme. The simulations results show that, E-HWMP protocol performed better than Ad-hoc on demand Distance Vector (AODV) routing protocol. Furthermore, E-HWMP is compared with other cluster-based gateway selection that used in the previous works; the result shows that our E-HWMP protocol outperforms the other cluster based gateway selections schemes in terms of connection delay, control packet overhead, packet delivery ratio and overall throughput.

Reliable Buffering Management Algorithm Support for Multicast Protocol in Mobile Ad-hoc Networks

Multicasting is one of the relevant issues of communication in infrastructure or centralized administration networks. The reliable delivery of multicast data packets needs feedback from all multicast receivers to indicate whether a retransmission is necessary. A reliable multicast delivery in the wireless Ad-hoc network requires a multicast packet to be received by all multicast receiver nodes. Thus, one or all members need to buffer data packet for possible error recovery. Furthermore, different buffer strategies are essentially used in existing reliable multicast protocols towards support error recovery and reducing buffer overflow. This study proposed two algorithms to improve the performance of the source tree reliable multicast (STRM) protocol. The first algorithm was developed to avoid buffer overflow in the sender node as the forward server (FS) nodes of STRM. This reduction is achieved by managing the buffer of the FS nodes, i.e., selecting the FS nodes depending on its empty buffer size and reducing the feedback sent from the receiver nodes to their FS node. The second algorithm was developed to decrease duplicated packets in the multicast members of the local group, which may be achieved by sending the repair packets to the requesting member. The FS in the local group should create a dynamic and temporary subgroup whose members are only those that requested the repair packet retransmission. The algorithms were tested using detailed discrete event simulation models encompassing messaging systems including error, delay, and mobility models to characterize the performance benefits of the proposed algorithms compared with the existing wireless Ad-hoc network protocols. Several experiments were conducted, revealing numerous results that verify the superior performance of the proposed algorithms over the existing algorithms.