Wireless Personal Area Networks

In this paper, a technique for improving parallel interference cancellation (PIC) receiver with linear estimators is studied in a CDMA system under power control and near-far case. By multiplying the received signal for each user in early stages by a factor superior than unity, the proposed technique significantly reduces the harmful impact of the bias upon BER performance and requires only one-implementation under power control. In order to make the analysis more tractable, the proposed bias mitigation technique is described for a synchronous multi-user communication scenario with binary signalling, non-orthogonal multiple access interference in an additive white Gaussian noise channel.

A wireless body area network (WBAN) aims to provide real-time and ubiquitous body monitoring to perform autonomous early prediction, diagnostic, and tracking the response of the body to treatments. IEEE 802.15.6 is a communication standard for WBANs which pervasively and continuously monitor the human body. In this paper, we develop an analytical model for performance evaluation of the IEEE 802.15.6 standard under non-saturation regime. We validate the analytical results by a simulation model. The result of the paper indicates that adopting appropriate EAPs and RAPs lengths noticeably improves the performance of the network. The short EAPs and RAPs result in wasting the network resources due to increasing the time intervals in which the medium is inaccessible. On the other side, long EAPs and RAPs increase the collision probability at the end of EAPs and may result in undesirable frame delays for highest user priority nodes.

A mobile, multi-hop wireless computer network, also termed as ad-hoc network, can be envisioned as a collection of routers, equipped with wireless transmitter / receiver, which are free to move about arbitrarily. The basic assumption in an ad-hoc network is that some node willing to communicate may be outside the wireless transmission range of each other but may be able to communicate if other nodes in the network are willing to forward packets from them. However, the successful operation of an ad-hoc network will be hampered, if an intermediate node, participating in a communication between two nodes, moves out of range suddenly or switches itself off in between message transfer. The objective of this paper is to introduce a parameter, affinity, that characterizes the strength of relationship between two nodes and to propose a distributed routing scheme between two nodes in order to find a set of paths between them which are more stable and less congested in a specific context. Thus, the communication in an ad-hoc wireless network can be effective by making the nodes in the system communication-aware in the sense that each node should know its affinity with its neighbors and should be aware of the impact of its movement on the communication structure of the underlying network.

To fulfill the requirements of high-speed, short-range wireless multimedia applications, millimeter-wave wireless personal area networks (WPANs) with directional antennas are gaining increased interest. Due to the use of directional antennas and mmWave communications, the probability of non-interfering transmissions increases in a localized region. The network throughput can immensely increase by the concurrent time allocation of noninterfering transmissions. The problem of finding optimum time allocation for concurrent transmissions is an NP-hard. In the literature, few "sub optimum concurrent time slot allocation" schemes have been proposed. In this paper, we propose two enhanced versions of previously proposed Multihop Concurrent Transmission (MHCT) scheme. To increase the network capacity, these schemes efficiently use the free holes in the time allocation map of MHCT scheme and make it more compact.

The convergence of heterogeneous wireless access technologies characterizes the 4G wireless networks. In such network environment the user equipped with multiple network interfaces, would want to roam between different networks without any interruption in the running applications and services, in such a way that minimize the network usage cost. This paper proposed a algorithm to decide the best network at best time moment to handoffs. The proposed algorithm make the right vertical handoff decisions by determining the suitable network at required time among available networks based on dynamic factors such as Received Signal Strength(RSS) of network and velocity of mobile station as well as static factors such as Offered bandwidth, Power Consumption and Network usage cost. The proposed algorithm not only meets the individual user needs but also improve the whole system performance by reducing the unnecessary handoffs. The proposed algorithm is successfully developed, simulated and ana...

The focus in this review paper for new technology about to satellite, it's similar to satellite but its station is stratosphere. Firstly introduces the wireless communications and then switches to fourth generation in wireless communications. Then discusses about High Altitude Airships, the "STRATELLITES" which are actually unmanned Kelvar balloons filled with helium gas which are used instead of towers for wireless communication, each of which replace hundreds of towers and reduce the cost of wireless communications. They also overcome the disadvantage of simple towers which could not provide proper coverage in the hilly areas.

In this paper, we consider an adaptive single dwell serial search system of pseudo-noise (PN) sequence s for direct sequences spread-spectrum (DS-SS) systems in no fading additive white Gaussian noise channels. Since the received signal levels in mobile communications are unknown and location varying, the acquisition schemes for pseudo-n oise (PN) sequences with fixed thresholds may cause too many false alarms. Therefore, adaptively varying thresh old schemes are proposed through the use of a constant false alarm rate (CFAR) algorithm. From the simulation results, w e observe that the DS/CDMA systems with CFAR processor outperforms the conventional scheme with fixed threshold.

A turbo-equalization technique is presented for transmissions, where QAM constellations are constructed via blockpartitioning as linear combinations of rotated, separately channel-coded BPSK components. The multilevel encoded QAM can be decoded with multistage decoding level-bylevel. Iterative equalization and multistage decoding is performed via soft interference cancellation and MMSE equalization followed by soft-in-soft-out channel decoders. Due to binary channel codes both the equalizer and decoder can operate with binary likelihood values without requiring symbolibit conversion. The resulting scheme is suitable for robust transmission when transmitter has little or no knowledge of channel quality.

In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, 1 agree that the Library shall make it freely available for reference and study. 1 further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission.

Abstract—We propose random relaying of MDS codeword blocks in cooperative multi-hop networks and evaluate its performance over random error channels by means of an absorbing Markov chain. The proposed scheme can apply to cooperative multi-hop networks with the arbitrary number of relay nodes at each hop stage and require no feedback channels between nodes. In the proposed scheme, a message block is encoded by a MDS code of coding rate 1 / L , where L is an integer. A relay node partitions a codeword of the MDS code into L blocks and transmits one randomly selected codeword block. When each relay node receives two or more codeword blocks of the MDS code, it aggregates the blocks, corrects channel errors with the aid of the MDS code or its punctured code. Numerical results indicate that significant improvement can be achieved by incorporating random relaying of MDS codeword blocks.

Broadcast of a message to nodes in a network is one of elementary but inevitable techniques in wireless ad-hoc and sensor networks. In this paper, we apply the protocol, which the authors proposed for cooperative multi-hop relay networks, to message broadcast over random error channels. Performance is evaluated in terms of the delivery ratio by means of computer simulations. The proposed protocol utilizes an MDS code and a relay node randomly transfers one of partitioned codeword blocks rather than the original message. We suppose a network of square-lattice topology as a preliminary example. Numerical results show that the significant performance improvement can be achieved, in particular, if a relay node can make use of previously received erroneous codeword blocks in the decoding procedure of the MDS code. ESSAGE broadcast is a common scenario in wireless ad-hoc and sensor networks. For example, in the AODV (Ad-hoc On-demand Distance Vector) routing protocol, RREQ (Route-Request) messages should be properly broadcast in order to find a route to the destination . When we deliver a message to all the nodes in a network, ``flooding'' is the most simple and basic mechanism . In the flooding mechanism, every relay node transfers the message, upon its first reception, to nodes within its transmission range. Performance of the flooding mechanism has been investigated, for example, from the viewpoint of the connectivity among nodes in conjunction with the percolation theory [3]- . In [3], the probability of survivability of the flooding is discussed. In [4], the forwarding Manuscript

In Wireless Mesh Networks (WMNs), Gateways (GWs) plays an important role as they connect the WMN to a large number of wired networks. As a result all traffics are aggregated at the GW nodes which leads to traffic congestion at the GW and hence results in quicker failure of the GW. Due to limited capacity of the gateway, large number of packet drops occurs at the gateways which degrade the performance of the WMN. Hence this paper addressed the Load balancing of WMN. To do so, a clustering technique is been considered which divides the WMN into a number of clusters. After cluster formation, a cluster head is selected within each cluster, comprising all the information of each and every node and coordinates the transmission of packets\traffic within each cluster and also may exchange data to neighboring nodes. This paper proposed a k-means clustering method to divide the WMN into k clusters and hence to reduce its load within each cluster. The implementation of the proposed k-means clustering method partitions the WMN into number of clusters. The cluster head(GW) is selected depending on various parameters, such as to reduce the load of each cluster. The simulation results prove that the performance of a WMN increased with the implementation of the proposed clustering method. IJOAR© 2015 I.

Communication at mmWave frequencies has been the focus in the recent years. In this paper, we discuss standardization efforts in 60 GHz short range communication and the progress therein. We compare the available standards in terms of network architecture, medium access control mechanisms, physical layer techniques and several other features. Comparative analysis indicates that IEEE 802.11ad is likely to lead the shortrange indoor communication at 60 GHz. We bring to the fore resolved and unresolved issues pertaining to robust WLAN connectivity at 60 GHz. Further, we discuss the role of mmWave bands in 5G communication scenarios and highlight the further efforts required in terms of research and standardization.

Transmission in the 60 GHz frequency band performs poorly in long-distance direct links due to the large path loss. The received signal strength can be relatively weak if the line-of-sight path is blocked by obstacles. A device cooperation approach, which effectively combats the severe path loss thereby improving the overall throughput for wireless personal area networks (WPANs), is proposed in this paper. Throughput maximization is formulated as a linear programming problem and the optimal solutions are provided in each case. Comprehensive simulations are performed to quantify the performance of the cooperative approach with different antenna models and spatial reuse strategies. The effect of minor-lobe, imperfect information and other factors are investigated under different network settings. The performance analysis presented here can provide guidelines for the design of cooperative 60 GHz WPANs.

In a multi-node network, cooperation among nodes is an effective means to enhance coverage and potentially increase the capacity. For such systems, schemes based on incremental relaying have great potential to improve the spectral efficiency by adapting the transmission to time varying channel conditions. The performance enhancement brought about by the presence of relays in such incremental relaying based cooperative systems is dependent on the level of cooperation (based on the relay information quality) and on coordination among the nodes. Coordination is achieved through the use of feedback channels, which incurs significant bandwidth penalty and brings down the spectral efficiency. In order to mitigate this, one can exploit an implicit feedback channel available due to broadcast nature of relay transmissions. Instead of using dedicated feedback channels, the implicit feedback channel is used to measure the relay information quality. Based on this information, the transmitter (source/relay) for the additional coded (redundancy) bits is determined. Such a mechanism enhances the reliability as it ensures the availability of correct information at the destination node for decoding. This paper studies the impact of such an implicit feedback channel by employing powerful codes which exhibit inherent incremental redundancy features, such as rate-compatible codes (rate-compatible punctured convolutional (RCPC) codes and punctured low-density parity-check (LDPC) codes) and rateless codes (Luby Transform (LT) codes). Theoretical analyses of the proposed scheme are presented, and supported with results from extensive simulation studies.

To fulfill the requirements of high-speed, short-range wireless multimedia applications, millimeter-wave wireless personal area networks (WPANs) with directional antennas are gaining increased interest. Due to the use of directional antennas and mmWave communications, the probability of non-interfering transmissions increases in a localized region. The network throughput can immensely increase by the concurrent time allocation of noninterfering transmissions. The problem of finding optimum time allocation for concurrent transmissions is an NP-hard. In the literature, few "sub optimum concurrent time slot allocation" schemes have been proposed. In this paper, we propose two enhanced versions of previously proposed Multihop Concurrent Transmission (MHCT) scheme. To increase the network capacity, these schemes efficiently use the free holes in the time allocation map of MHCT scheme and make it more compact.

We propose an over 1.2 Gbps throughput wireless LAN system based on IEEE802.11TGac's requirements. It reaches 33 meter propagation distance by using 80MHz of bandiwdth on 5GHz band. 4 × 5 antennas configuration contribute 2 nd -order diversity gain and maintain both the high throughput and the high performance. The proposed Greenfield format preamble has high preamble efficiency. Novel phase rotation is employed to get low PAPR signal of preamble and data fields. 3 different coding rates are examined for 64-QAM constellation which all accomplish over 1 Gbps with maximum throughput 1.266 Gbps. Run test for transmitting 90 frames of 4096×1714 pixels/frame digital cinema under in-door channel model proves the excellent performance of the proposed system.

This paper presents the measurement and statistical analysis of the temporal variations of the radio channel defined by a fixed link at 3.5 GHz in suburban areas. The analysis provides the required information about the temporal stability of the channel, the probability of occurrence and depth of fades, the Doppler spectrum and, in general, the influence of the environment on the signal behaviour. In particular, the effect of fast traffic on a motorway in the neighbourhood of the receiver is investigated, obtaining some general conclusions particularly useful in wireless communication systems design.

nPoA nPoA BTS B BTS C BTS D Administrative Domain B Corresponding Host IP ch N2 Configuration Agent Authentication h/o delay 900 ms 802.11 802.11 4 Seconds media interruption h/o delay 4 s Handoff Delay ~ 18 s 802.11 CDMA 18 Seconds media interruption h/o delay 18 s Key advantages: Key advantages: 1)Provides the ability to discover the network elements prior to handover without relying on underlying layer 2 discovery mechanism after the handover 2) eliminates layer 2 scanning delay during handover by caching the channel number

In this paper, we propose and experimentally demonstrate a simple, cost-effective hybrid gigabit fiber-wireless system for in-building wireless access. Simplicity and cost-effectiveness are achieved in all parts of the system by utilizing direct laser modulation, optical frequency up-conversion, combined single mode/multimode fiber transmission and envelope detection. Error-free transmission of 2-Gbps data in 60-GHz band over a composite channel including 10-km standard single-mode fiber (SSMF)/1-km multimode fiber (MMF) and 6.5-m air transmission was successfully achieved.

Existing terminal oriented handover mechanisms capable of meeting the strict delay bounds of real time applications such as VoIP do not consider the QoS of candidate handover networks. In this paper ECHO -a QoS based handover solution for VoIP-is proposed. ECHO is endpoint centric and does not require any network support; it leverages the SCTP transport protocol. ECHO incorporates network metrics that directly affect VoIP quality into the handover decision process. A dynamic variant of the ITU-T E-Model is used to calculate how the network metrics map to a user perceived voice quality metric known as the MOS. The MOS value is then used to make handover decisions between each of the available access networks. The results show that the addition of the QoS capabilities significantly improves the handover decisions that are made.

Algebraic Space-Time Codes (ASTC) for Multiple Input Multiple Output (MIMO) systems are based on quaternion algebras. Thanks to their algebraic construction, the ASTC codes are full-rank, full-rate and have the non-vanishing determinant property. These codes have been proposed for MIMO flat fading channels in order to increase the spectral efficiency and to maximize the coding gain. The purpose of this work is to analyze the performance of the ASTC in a frequency selective Rayleigh channel. To deal with the frequency selectivity, we use the OFDM modulation. The capacity performances of an ASTC-MIMO-OFDM system, under correlated Rayleigh frequency-selective channel, have been evaluated.

Apresentar os conceitos de middleware como uma infraestrutura de apoio à construção e execução de sistemas colaborativos. Após o estudo desse capítulo, você deverá ser capaz de: • Definir as características de um sistema colaborativo que levam à adoção de uma infraestrutura de middleware. • Selecionar uma plataforma de middleware de acordo com as necessidades do desenvolvedor. • Identificar os principais elementos de um middleware para apoiar o desenvolvimento de sistemas colaborativos.

An integrated model is proposed that comprises essentially, an Enhanced Profile-Based Strategy (EPBS) for small-scale roaming and a Caching Two-Level Forwarding Pointer (C2LFP) strategy for large-scale roaming. The idea behind the integrated model is how those two location management solutions are applied, and what is the suitable approach to specify the physical parameters of PCS networks from mobility management's point of view so that our solutions can be more cost effective for location management. An evolutionary method, using a constrained Genetic Algorithm (GA) has been used to achieve network parameters optimization. For convenience, we selected the underlying planning problem with an appropriate set of parameters so that it can be treated, in what follows, both genetically and analytically. Thus one can easily verify the accuracy and efficiency of the evolutionary solution that would be obtained from the genetic algorithm. For more realistic environments, GA could be used reliably to build up sophisticated models that integrate the small-scale and large-scale roaming parameters of PCS networks. The results that have been obtained from a case study are presented in order to provide a deep explanation for the proposed integration approach.

One major drawback associated with an OFDM system is that the transmitter's output signal may have a high peak-to-average ratio (PAPR). High levels of PAR may be a limiting factor for power line communication (PLC) where regulatory bodies have fixed the maximum amount of transmit power. To overcome this problem, many approaches have been presented in the literature. One potential solution for reducing the peak-to-average power ratio (PAPR) in an OFDM system is to utilize a constant envelope OFDM (CE-OFDM) system. This paper describes a CE-OFDM based modem for Power Line Communications (PLC) over the low voltage distribution network. The impact of the electrical appliances on the signal transmission is investigated. The good performances of the BER have been checked by the simulation platform of real PLC channel using Matlab. Finally, CE-OFDM-CPM is compared with conventional OFDM under HomePlug AV..

Navigation applications are becoming standard features in more and more commercially available devices. Locating a mobile user is however still a very challenging task, especially in GNSS degraded areas such as urban canyons and indoors. A seamless indoor/outdoor positioning solution requires utilizing additional technologies in parallel to satellite navigation due to satellite signals being often unattainable in for example deep indoors, or the high noise levels of the satellite signals available are causing significant degradation ...

Este artigo descreve os requisitos de sistema encontrados através de (i) uma busca na literatura científica sobre estudos relacionados ao hardware para uso de jogos digitais sérios ativos (exergames) com a população com transtorno do espectro autista (TEA) e (ii) uma lista de requisitos para desenvolvimento de exergames para chão interativo, criada através de entrevistas com 41 especialistas na área de TEA. Foram estabelecidos 3 requisitos de hardware e 27 requisitos de software para um exergame de chão interativo objetivando processamento sensorial.

IEEE 802.15.6 standard defines the Physical and Medium Access Control layers for Medical Body Area Networks (MBAN), where many sensor nodes can communicate with a central hub using a wireless medium. The standard specifies the user priorities and contention window range for the sensor nodes to enable them to achieve the best throughput and high reliability. However, there are eight distinct priority levels (UP0-UP7) which may be assigned to a maximum of sixty-four nodes, resulting in multiple nodes being assigned the same user priority. In such cases local priority needs to be assigned to the nodes within the UP and data throughput must be optimized. In this work, we have used Criteria Importance Through the Intercriteria Correlation (CRITIC) where nodes are put in a priority queue by assigning them local user priority within one of the eight priority levels UP0 to UP7, as defined in IEEE 802.15.6. The method optimizes the backoff count value to minimize the delay for data packets from these nodes in the queue. We have done simulations where results show that the backoff values and the local priorities calculated using CRITIC based upon sensor parameters – packet size, packet generation rate, and data transmission rate improve the throughput of sensors in UP0-UP6.

The revolutionary changes the Mobile Telecommunications Industries is going through are forcing the Mobile Network Operators (MNOs) to radically reshape their strategies, according to the newly emerged market's value drivers. The purpose of this study is to provide an original reference model for supporting the analysis of MNOs' strategic positioning. Employing the multiple exploratory case studies research methodology, the study identifies five dimensions or classification variables -Content creation & innovation management, Mobile Advertising integration, Communities and Social Networking focus, Charging & billing systems leverage and Network infrastructure management -through which describing and assessing an MNO's strategic positioning; consequently the model is applied to the four Italian operators, so to obtain a validation as well as a picture of the adopted strategic positioning. The findings show two alternative and quite contradictory "strategic extremes" the operators are swinging between seem to be emerging: the Pure Carrier positioning, and the Media Company positioning. In between, the Smart Pipe positioning sees the operator making the most out of its assets, gaining the role of the third parties' offer enabler.

Nowadays, the concept of spatial diversity and cooperative networks attract a lot of interest because they improve the reliability of transmission in wireless networks. Spatial diversity is achieved when multiple antennas are at the transmitter. With great growth and demand for high speed high data rate wireless communication, more and more antennas are required. In order to achieve maximum diversity, these antennas should be well separated so that the fading on each link is uncorrelated. This condition makes it difficult to have more than two antennas on a mobile terminal. The relay's cooperation helps increase the diversity order without extra hardware cost. However, its main inconvenience is the use of multiple time slots compared to the direct link transmission. In this thesis, we develop a cooperation model which is composed of three terminals: source, relay and destination. The transmitters (source and relay) are composed of 2 antennas at the transmitter and the receivers (relay and destination) have 4 antennas. In the first proposed model, transmitters and decoders are composed of an Alamouti encoder and decoder respectively. In the second model, we also add a turbo encoder at transmitters and iterative decoding takes place at receivers. In both cases, the transmission cycle is composed of two time slots and the decode and forward (DF) protocol is applied. Multiple scenarios are considered by changing the environment of the CHAPTER 5: CONCLUSION AND FUTURE WORK .

Aplicações móveis têm sido motivo de grande interesse nos últimos anos. Diversas aplicações baseadas em conceitos totalmente novos estão sendo criadas tirando vantagem da computação onipresente. Os exercícios militares em campo são necessários para a preparação da tropa e o emprego de exercícios com estações móveis representa uma nova alternativa de apoio ao adestramento no Corpo de Fuzileiros Navais. Este artigo tem como principal objetivo investigar plataformas que possibilitem a utilização da computação móvel nos exercícios do Corpo de Fuzileiros Navais, apresentando um protótipo desenvolvido em uma das plataformas propostas. Palavras-chave: bancos de dados, exercícios de guerra, computação móvel.

Enormous research, standardization and development efforts continue to be allocated in all areas related to wireless communications. These efforts result to a powerful, high-speed infrastructure that offers several wireless/mobile connectivity solutions to the digital information society. Currently, the wireless landscape includes several Radio Access Technologies (RATs), e.g., 2.5G/3G/4G mobile infrastructures, the suite of IEEE 802 wireless technologies, Digital Audio/Video Broadcasting (DAB/DVB). Moreover, significant research effort is dedicated to the elaboration of the era of wireless communications, Beyond the 3rd Generation (B3G), in which the available RATs will form an heterogeneous infrastructure that will have to exist in an environment also characterized by the advance of the Internet, the need for broadband everywhere, the convergence of digital industries, the advance of e-commerce, deregulation and globalization, and above all the fact that services and applications are key: the end user is interested in services and applications, and should be served and managed in a way that the underlying infrastructure complexity is abstracted. Moreover, future systems should be sufficiently flexible to match the unpredictable operator and user expectations from a service and economic perspective. In response to the characteristics above, future wireless systems shall respond to versatile requirements, such as the fact that users shall be in control through intuitive interactions with applications, services, and devices. Those services and applications will be personalized, ambient-aware, and adaptive, provided ubiquitously from the user viewpoint. In addition, machines (autonomously communicating devices) shall operate irrespective of place and network, and with agreed quality-of-service (QoS). Those issues allow users, application developers, service and content providers, network operators, and manufactures to efficiently and flexibly create new services and business models based on the component-based architecture of the wireless world. In the light of the aspects above, the goal of this special issue is to present advances in various research areas related to the B3G wireless world, relevant applications, services, and infrastructure technologies. In this respect, a great variety of interesting issues are tackled,

Cooperative transmission is a new communication strategy that takes advantage of the broadcast aspect of wireless channels to increase transmission by allowing network nodes to cooperate. Its potential for further application in wireless networks is limited due to its low spectral efficiency and the requirement for orthogonal channels. Using MUD, a cooperative transmission protocol with good spectrum efficiency, diversity gain, and coding gain was developed in this study. The benefit of MUD cooperative transmission methods is that improving one user's link can help other users. By completely exploiting the link between the relay and the destination, the coding and high diversity order can be attained. In this case, one of the nodes will operate as a relay, facilitating collaboration among the network's various nodes. MUD will determine which user will send the data and send it to the appropriate destination. Each node in our project will operate as a relay for any other node. Data loss and packet retransmission will be reduced as a result of this. The network's performance will improve as a result of this. We utilize a dynamic base station to ensure that nodes outside the network broadcast packets to the network's destination.

The Quality for Service Protocol draft-aranda-dispatch-q4s-02.txt Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."

Intelligent antennas offer the possibility of greatly increasing the capacity of cellular mobile radio systems. We give a comprehensive overview of the literature concerning model scenarios for applications of direction-selective intelligent antennas. Measurement campaigns and simplified models are described that have been derived from these measurements or from physical considerations. Furthermore, directional fading simulators are reviewed which are essential for

This paper introduces a new paging technique to track and wake up a mobile node (MN) attached to an access point (AP) in a wireless LAN network after a session initiation protocol (SIP) INVITE message is initiated by a caller. A tracking agent (TA) keeps track of the mobiles' handoffs between the APs. A paging agent (PA) triggers the TA to page the mobile when a SIP INVITE is received for one of its users. The context transfer feature of our paging protocol allows the paging messages to deliver the station context in order to enable faster session reestablishment. The AP then does onlink paging in a wireless link. SIP extensions are needed to trigger the PA to start paging MNs to notify their dormant status using an extended SIP REGISTER method. Tracking protocol is analyzed to compare soft-and hard-state approaches for state inconsistency ratio, message rate, and the overall cost. The simulation model we developed enables us to evaluate the traffic introduced by the tracking protocol and the cache (state) size. Paging protocol is analyzed for CPU processing times and the transmission delays in the SIP session setup with paging. Simulation of the paging with context transfer is used to show the gains in reauthentication. Index Terms-Context transfer, fluid flow and random walk mobility model, onlink paging, paging agent (PA), session initiation protocol (SIP), tracking agent (TA).

Abstract—The L-MMSE (Linear Minimum Mean Square Error) DS-CDMA (Direct Sequence-Code Division Multiple Access) receiver algorithm was adapted for the MIMO/BLAST (Multiple Input, Multiple Output / Bell Laboratories Layered Space Time) system in order to ...

The development of next generation protocols, such as UDT (UDP-based data transfer), promptly addresses various infrastructure requirements for transmitting data in high speed networks. However, this development creates new vulnerabilities when these protocols are designed to solely rely on existing security solutions of existing protocols such as TCP and UDP. It is clear that not all security protocols (such as TLS) can be used to protect UDT, just as security solutions devised for wired networks cannot be used to protect the unwired ones. The development of UDT, similarly in the development of TCP/UDP many years ago, lacked a well-thought security architecture to address the problems that networks are presently experiencing. This paper proposes and analyses practical security mechanisms for UDT.

User mobility in WLANs becomes more and more popular because of wide deployment of WLANs and numerous applications on it. Some of these applications, for example multimedia applications, require fast handoffs among access points to maintain the quality of service. In order to support multimedia applications for roaming users, IEEE 802.11i defines pre-authentication to reduce the re-authentication delay. The primary drawback of IEEE 802.11i pre-authentication is that the full 802.1x/EAP authentication consumes too much overhead. In this paper, we propose a new fast pre-authentication scheme that greatly improves the efficiency and achieves high security level.

Wireless Mobile Communication systems will be more sophisticated and wide spread in future. This growth demands not only for capacity increase, but also high quality of service and better coverage without increase in the radio frequency spectrum allocated for mobile applications. Smart antenna is one of the promising technologies for achieving efficient networks that maximize capacity and improve quality and coverage. These Smart antennas dynamically adapt to changing traffic requirements. The core of smart antenna is the selection of smart algorithms in adaptive array. Using beam forming algorithms, the weight of antenna arrays can be adjusted to form certain amount of adaptive beam to track corresponding users automatically and at the same time to minimize interference arising from other users by introducing nulls in their directions Smart antennas are usually employed at the base stations and they radiate narrow beams to serve different users. This work looked at the Smart Antenna technology and its principles of operation, and the associated benefits obtainable from its implementation in a mobile cellular network.

IoN adopts an incremental and evolutionary approach to mobility management by enhancing existing solutions to vertical handovers based on existing business models. The current cellular business model is operator centric illustrated in Figure 2. This means the network operator has telecom as their core business and oriented towards filling the network with traffic and earning money on mobile services only. In this model, each user has an initial subscription with the so called home network and uses standard network specific procedures and parameters for authentication. The network operator maintains a subscriber database containing the profiles and all user service related definitions. In addition, this model provides integrated robust authentication and billing mechanisms as well as rigid security features that establish an important level of trust between the operators and its subscribers.

Emergent services are demanding higher data rates, especially in the downlink. Wideband Code Division Multiple Access (WCDMA) is the key to reach this development in cellular communications. To obtain this, it is important to find schemes able to reduce Inter-Path Interference (IPI) and Multiple Access Interference (MAI), and to explore new types of diversity. These are the objectives of the present thesis. Interference cancellation subject considers post-processing and pre-processing schemes. A new linear MultiUser Detector (MUD) is proposed and analyzed. As pre-processing schemes, the new Pre-distortion and the Precoder schemes are studied and analyzed. New types of diversity are also presented and analyzed. A new post-processing detector for the Vertical Bell Laboratories Layered Space-Time (V-BLAST) Multiple Input Multiple Output (MIMO) scheme, optimized for WCDMA signals subject to frequency selective fading, is proposed and analyzed. Moreover, a new frequency domain pre-processing scheme for frequency-selective fading MIMO channels is also proposed and analyzed. The new Beam-Selective Transmit Diversity (BSTD) can be seen as a composite scheme where the MAI reduction is performed jointly with the exploration of transmit diversity, without additional Mobile Station (MS) complexity. It is shown that, in most conditions, the pre-processing scheme for MIMO channels tends to achieve the best performance in most scenarios, being followed by the BSTD which allows interference cancellation and provides diversity. Both schemes tend to lead to good performances and capacities, facing the requirements of the emergent cellular communication systems. Depending on the complexity and size constraints imposed to the MS, the present thesis suggests the scheme that should be selected to allow such improvements.

Nowadays in deployment and flexibility in radio resources configuration are the main features of future wireless communication system. A cooperative wireless communication system is proposed to follow the same principle aiming at improving the all over performance of wireless system. In this paper we will analyze the recent developments and trends in the area of wireless Ad hoc network. This article will also discuss various main cooperative signal methods.

I would like to thank my adviser, Dr. Fernando J. Velez, for all the knowledge and guidance he provided during this journey. I also want to thank several friends that helped me with the work that will be presented in the following pages and highlight that this work would not be possible without their help. First of all I would like to thank the engineer Rui Paulo for the support, friendship, and for his help with the work involving the LTE-Sim, for the knowledge he shared and for the codes he provided that made it possible to perform most of the simulations done with LTE-Sim. To Bruno Cruz for his friendship during all my time in Portugal and for the help he provided with the code he developed that were key to the results that will be shown in this thesis. To my great Brazilian friend Rooderson Andrade, who not only helped me with the knowledge about MIMO but also supported me in all moments. To Marisa Lourenço, my college at the Instituto de Telecomunicações who helped a lot with the work performed with Matalab.To Emanuel Teixeira for his support in several aspects of this work, specially with the work involving Matlab. To Emanuel Mahina, another college from the Instituto de Telecomunicações whose friendship and insights were of paramount importance. To all the teachers I had during this Master course and that guided me through the different areas of knowledge that contributed to this work. Finally, I would like to thank the Instituto de Telecomunicações for the opportunity, and for the scholarship supported by National Founding from FCT through CONQUEST (CMU/ECE/030/2017), for the support provided via National Founding from FCT through the UID/EEA/50008/2013, and as well as for the equipment provided by ORCIP (CENTRO-01-0145-FEDER-022-141) and for the support from COST CA 15104.

Mobile ad hoc network is a network technique, which connects two or more mobile computers with each other without existence of a central point of contact, and without any network server, which is the role of each point, pass packets to other branches of the network. The proposed work is to attempt to identify the performance of data traffic patterns (CBR, FTP and POISSON) in Zigbee personal area networks (PAN) using MANET routing protocols (AODV, DSR and INTANTSENSE). Simulation and computations of data loss, overhead, throughput, PDR and delay done using NS2 simulator (Version 2.34) with parameter of quality of data and pause time.

Mobile ad hoc networks (MANET) have emerged as an important field in the wireless area. Due to its dynamic nature, a primary challenge of MANET is the design of effective routing algorithm that can adapt its behavior to frequent and rapid changes in the network. This paper presents a novel scheme for MANET routing enhancement called Intelligent Ant sense (INTANTSENSE) protocol based on ant colony optimization. It utilizes a collection of mobile agents to perform optimal routing activities. By combining the capability of reactive routing with distributed and multipath routing mechanism, Intelligent Ant Sense routing compared with AODV protocol using network simulator-2 (NS-2).INTANTSENSE protocol utilizing the benefits of pheromones, third party reply model and ring search model, to enable optimal path routing, fast route discovery and effective Sense routing route failure handling.

The paper focusses on the use of wireless networks, with special emphasis on Wi-Fi, in the manoeuvering and apron areas of an airport to control the ground vehicles movements in those areas and, consequently, to improve user safety, efficiency of operations and airport security. The use of Wi-Fi for these purposes constitutes a novel approach in an airport environment. Other wireless networks, namely CDMA and Tetra, are also experimented in this project as a lower bit-rate alternative to Wi-Fi. The platform consists of an onboard system in each vehicle, a centralised ground system and wireless networks to allow the communication between the vehicles and ground system. The architecture, protocols and network configurations in use are analysed as well as the respective deployment made in the airport of Porto in Portugal.