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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.

Femtocell is a recently developed technology in cellular wireless networks, which extends network coverage indoors, and is used to serve a small number of users. Synchronisation is one of the most significant technical challenges in femtocell networks and it guarantees an acceptable clock offset and frequency error skew. Clock offset and skew lead to severe interference between femtocell base stations fBSs or between fBSs and macrocell base stations mBSs. The ultimate objective of this paper is to develop cluster-based time synchronisation scheme to reduce clock offset and skew in terms of precise synchronisation in fBS neighbouring nodes. In consequence with the developed cluster-based time synchronisation scheme, the intra-cluster and inter-cluster time synchronisation is proposed. The proposed scheme is evaluated through analytical approach and benchmarked with mobile station-assisted synchronisation scheme. Results show that the proposed scheme is able to significantly reduce clock offsets to 53% and 60.32% for clock skew.

The novel "femtocell" in Heterogeneous Network (HetNet) for LTE-Advanced (LTE-A) set-up will allow Malaysian wireless telecommunication operators (Maxis, Celcom, Digi, U-Mobile, P1, YTL and etc2.) to extend connectivity coverage where access would otherwise be limited or unavailable, particularly indoors of large building complexes. A femtocell is a small-sized cellular base station that encompasses all the functionality of a typical station. It therefore allows a simpler and self-contained deployment including private residences. For the Malaysian service providers, the main attractions of femtocell usage are the improvements to both coverage and capacity. The operators can provide a better service to end-users in turn reduce much of the agitations and complaints. There will be opportunity for new services at reduced cost. In addition, the operator not only benefits from the improved capacity and coverage but also can reduce both capital expenditure and operating expense i.e. alternative to brand new base station or macrocell installation. Interference is a key issue associated with femtocell development. There are a large number of issues associated with interference all of which need to be investigated, identified, quantified and solved. This is to ensure that the deployment of any femtocells will take place successfully. Among the most critical challenges in femtocell deployment is the interference between femtocell-to-macrocell and femtocell-to-femtocell in HetNets. In this paper, all proposed methods and algorithms will be investigated in the OFDMA femtocell system considering HetNet scenarios for LTE-A.

NEMO BSP is an upgraded addition to Mobile IPv6 (MIPv6). As MIPv6 and its enhancements (i.e. HMIPv6) possess some limitations like higher handoff latency, packet loss, NEMO BSP also faces all these shortcomings by inheritance. Network Mobility (NEMO) is involved to handle the movement of Mobile Router (MR) and it's Mobile Network Nodes (MNNs) during handoff. Hence it is essential to upgrade the performance of mobility management protocol to obtain continuous session connectivity with lower delay and packet loss in NEMO environment. The completion of handoff process in NEMO BSP usually takes longer period since MR needs to register its single primary care of address (CoA) with home network that may cause performance degradation of the applications running on Mobile Network Nodes. Moreover, when a change in point of attachment of the mobile network is accompanied by a sudden burst of signaling messages, "Signaling Storm" occurs which eventually results in temporary congestion, packet delays or even packet loss. This effect is particularly significant for wireless environment where a wireless link is not as steady as a wired link since bandwidth is relatively limited in wireless link. Hence, providing continuous Internet connection without any interruption through applying multihoming technique and route optimization mechanism in NEMO are becoming the center of attention to the current researchers. In this paper, we propose a handoff cost model to compare the signaling cost of MM-NEMO with NEMO Basic Support Protocol (NEMO BSP) and HMIPv6.The numerical results shows that the signaling cost for the MM-NEMO scheme is about 69.6 % less than the NEMO-BSP and HMIPv6.

Deploying femtocell in heterogeneous network (HetNets) are promising because of improved coverage as well as system capacity. The challenge for inter-cell and intra-cell interference has taken seriously by the industry. However, some distinctive characteristics presents key problem to mitigate the interference. The random deployment of femtocell (HeNodeB) and other small cell in HetNet becomes a key considerations issue because of interference which lead the performance degradation. The interference occurs between HeNodeB-to-macro cell and HeNodeB-to-HeNodeB in the case of uplink/downlink with the user equipments. Consequently, researchers have proposed some techniques to take over the interference in HetNet which need to be investigate, identify, quantify along with solution. Therefore, the aim of this study to evaluate the performance of potential interference alleviation schemes/techniques in Orthogonal Frequency Division Multiple Access (OFDMA) considering HetNets uplink/downlink scenario.

This paper presents a new clustering mechanism for the multi-hop relay in vehicular communication. In the proposed mechanism, the cluster-head selection is implemented using the enhanced hybrid wireless mesh protocol (E-HWMP) protocol, which is based on the IEEE802.11p and IEEE802.11s standards. Then, multi-hop routing is designed for VANET in Wireless Mesh Networks (WMNs). Therefore, the main aim of this study is to enhance the integration of VANET with a cellular network (i.e., LTE). As a result, the coverage can be extended. The proposed E-HWMP mechanism is evaluated by the NS2 simulator, and the VanetMobiSim is used as a mobility generator. The proposed E-HWMP mechanism is compared to the existing mechanism based on the packet’s delivery ratio, packet loss, throughput, overhead, and average end-to-end delay. The results demonstrate that the proposed E-HWMP mechanism outperforms the existing clustering mechanism.

Global thresholding and local thresholding are two basic ways for image binarization. Global thresholding, not suitable for complex documents, may produce noise along the page borders when the intensity of an image is non-uniform. For degraded, noisy and illuminated images local thresholding is preferred. This paper presents a local thresholding scheme when the image is a collection of text, pictures, and background. It calculates the local mean and local contrast to separate the background from the foreground. Local contrast, not suitable for integral images, can be achieved by the differing local maximum, and local minimum intensity. The proposed approach doesn’t calculate standard deviation like much other local thresholding method but locally adapted with local mean and local contrast. This proposed algorithm has been tested with different types of images including ancient documents, noisy background, and pictures. The test results are compared with a global and some traditional local thresholding techniques in terms of MSE and PSNR. The comparison shows that the proposed method results improved PSNR and better extraction in OCR operation.