On the minimum hop count and connectivity in one-dimensional ad hoc wireless networks

This paper investigates connectivity in one-dimensional ad hoc networks by means of the distribution of the minimum hop count between source and destination nodes. We derive the exact probability distribution of the minimum hop count from the location density of relay nodes in the multihop path selected with the Most Forward within Radius (MFR) scheme. The probability that the source and destination nodes are connected (provided by Ghasemi and Nader-Esfahani [IEEE Commun. Lett. 10(4):251–253, 2006]) can be obtained by summing the probability masses for each possible value of the minimum hop count, which provides new insights to the connectivity probability. Numerical results show the effect of the number of nodes and the transmission range on the minimum hop count

Route Availability model for Inter-working multi-hop wireless networks

The paper emphasizes that route availability is important

MODIFIKASI PROTOKOL AODV-BR MENGGUNAKAN LINK EXPIRATION TIME (LET) UNTUK MENINGKATKAN STABILITAS LINK DI LINGKUNGAN MOBILE Ad-Hoc NETWORK (MANET)

AODV protocol is a protocol that is fairly mature in mobile Ad-Hoc network. But the traditional AODV protocol in some ways it seems less satisfying, especially on the stability of data transmission. Development continues, one of which AODV-Backup Routing which became known AODV-BR, were present to address the stability issues of data delivery by providing a backup route, however, AODV-BR still use traditional routing paths that are vulnerable to termination due to the formation of these calculations are based on minimum hop. This study proposes a modified AODV-BR with reliability be the ability to build main route and to choose the route up to the value of the highest stability was then called AODV-Stable bacukp Routing (AODV-SBR). Armed algorithms Link Expiration Time with node movement calculation technique, so the AODV-SBR is able to calculate the value of the minimum and maximum connectivity nodes in a route as the main reference in establishing a delivery route data more stable. The results test of the both protocols in Packet Delivery Ratio (PDR), Throughput, End-to-En Delay and Routing Overhead shows that performance of AODV-SBR better than AODV-B

A framework for Connectivity in Inter-working Multi-hop Wireless Networks

Establishing connectivity between node pairs in inter-working multihop wireless networks is a challenge. Although connectivity in multi-hop wireless networks has been studied yet these analyses focused mainly on ad-hoc networks. Since the next generation of wireless networks will be inter-working, an understanding of connectivity as it applies to such networks is needed. Specifically, this research emphasizes that the connectivity between any node pair in an inter-working multi-hop wireless network should be estimated with the availability of links and the level of interference on the available links that form the communication route between the nodes. Interference is a major factor that inhibits connectivity as it can cause wasteful transmissions over low quality links. Therefore this paper presents a framework for connectivity in interworking multi-hop wireless networks. In addition a connectivity aware routing technique is proposed. Simulation results of the performance of the proposed routing technique in comparison with other routing scheme are presented

MODIFIKASI PROTOKOL AODV-BR MENGGUNAKAN LINK EXPIRATION TIME (LET) UNTUK MENINGKATKAN STABILITAS LINK DI LINGKUNGAN MOBILE Ad-Hoc NETWORK (MANET)

Protokol Ad-Hoc On-demand Distance Vector (AODV) merupakan salah satu protokol yang cukup matang pada jaringan mobile Ad-Hoc. Namun protokol AODV tradisional dalam beberapa hal tampaknya kurang memuaskan khususnya pada stabilitas pengiriman data. Pengembangan terus dilakukan, salah satunya AODV-Backup Routing yang kemudian dikenal dengan AODV-BR, hadir untuk mengatasi masalah stabilitas pengiriman data dengan menyediakan rute cadangan, namun demikian AODV-BR masih menggunakan routing tradisional yang rentan terhadap pemutusan jalur karena pembentukan rute didasarkan pada perhitungan minimal hop. Penelitian ini mengusulkan modifikasi AODV-BR dengan reliabilitas berupa kemampuan membangun rute utama dan cadangan dengan nilai stabilitas tertinggi yang kemudian disebut AODV-Stable Backup Routing (AODV-SBR). Berbekal algoritma Link Expiration Time (LET) dengan teknik perhitungan pergerakan node, maka AODV-SBR mampu menghitung nilai minimal dan maksimal keterhubungan node-node dalam sebuah rute sebagai acuan utama dalam membangun rute pengiriman data yang lebih stabil. Hasil uji kedua protokol dari sisi Packet Delivery Ratio (PDR), Throughput, End-to-En Delay dan Routing Overheadsecara keseluruhan memperlihatkan kinerja AODV-SBR lebih baik dibandingkan AODV-BR. =================================================================================== AODV protocol is a protocol that is fairly mature in mobile Ad-Hoc network. But the traditional AODV protocol in some ways it seems less satisfying, especially on the stability of data transmission. Development continues, one of which AODV-Backup Routing which became known AODV-BR, were present to address the stability issues of data delivery by providing a backup route, however, AODV-BRstill use traditional routing paths that are vulnerable to termination due to the formation of these calculations are based on minimum hop. This study proposes a modified AODV-BR with reliability be the ability to build main route and to choose the route up to the value of the highest stability was then called AODV-Stable bacukp Routing (AODV-SBR). Armed algorithms Link Expiration Time with node movement calculation technique, so the AODV-SBR is able to calculate the value of the minimum and maximum connectivity nodes in a route as the main reference in establishing a delivery route data more stable.The results test of the both protocols inPacket Delivery Ratio (PDR), Throughput, End-to-En Delay and Routing Overhead shows that performance of AODV-SBR better than AODV-BR

Physical and Link Layer Implications in Vehicle Ad Hoc Networks

Vehicle Ad hoc Networks (V ANET) have been proposed to provide safety on the road and deliver road traffic information and route guidance to drivers along with commercial applications. However the challenges facing V ANET are numerous. Nodes move at high speeds, road side units and basestations are scarce, the topology is constrained by the road geometry and changes rapidly, and the number of nodes peaks suddenly in traffic jams. In this thesis we investigate the physical and link layers of V ANET and propose methods to achieve high data rates and high throughput. For the physical layer, we examine the use of Vertical BLAST (VB LAST) systems as they provide higher capacities than single antenna systems in rich fading environments. To study the applicability of VB LAST to VANET, a channel model was developed and verified using measurement data available in the literature. For no to medium line of sight, VBLAST systems provide high data rates. However the performance drops as the line of sight strength increases due to the correlation between the antennas. Moreover, the performance of VBLAST with training based channel estimation drops as the speed increases since the channel response changes rapidly. To update the channel state information matrix at the receiver, a channel tracking algorithm for flat fading channels was developed. The algorithm updates the channel matrix thus reducing the mean square error of the estimation and improving the bit error rate (BER). The analysis of VBLAST-OFDM systems showed they experience an error floor due to inter-carrier interference (lCI) which increases with speed, number of antennas transmitting and number of subcarriers used. The update algorithm was extended to VBLAST -OFDM systems and it showed improvements in BER performance but still experienced an error floor. An algorithm to equalise the ICI contribution of adjacent subcarriers was then developed and evaluated. The ICI equalisation algorithm reduces the error floor in BER as more subcarriers are equalised at the expense of more hardware complexity. The connectivity of V ANET was investigated and it was found that for single lane roads, car densities of 7 cars per communication range are sufficient to achieve high connectivity within the city whereas 12 cars per communication range are required for highways. Multilane roads require higher densities since cars tend to cluster in groups. Junctions and turns have lower connectivity than straight roads due to disconnections at the turns. Although higher densities improve the connectivity and, hence, the performance of the network layer, it leads to poor performance at the link layer. The IEEE 802.11 p MAC layer standard under development for V ANET uses a variant of Carrier Sense Multiple Access (CSMA). 802.11 protocols were analysed mathematically and via simulations and the results prove the saturation throughput of the basic access method drops as the number of nodes increases thus yielding very low throughput in congested areas. RTS/CTS access provides higher throughput but it applies only to unicast transmissions. To overcome the limitations of 802.11 protocols, we designed a protocol known as SOFT MAC which combines Space, Orthogonal Frequency and Time multiple access techniques. In SOFT MAC the road is divided into cells and each cell is allocated a unique group of subcarriers. Within a cell, nodes share the available subcarriers using a combination of TDMA and CSMA. The throughput analysis of SOFT MAC showed it has superior throughput compared to the basic access and similar to the RTS/CTS access of 802.11