Syed Faraz Hasan

Femtocell versus WiFi - A survey and comparison of architecture and performance

Femtocells use common cellular air access technologies, but claim to improve system capacity according to Shannons law by reducing distance between transmitter and receiver and thus improving the signal-to-noise ratio (SNR). Femtocells, however, use the IP Network as backhaul architecture instead of the conventional cellular network infrastructure. Thus, femtocell and WiFi infrastructure networks have a lot in common. This raises a curiosity whether femtocell technology would replace existing WiFi technology. This can be answered only by carefully analyzing the similarities and differences between the two technologies. This paper provides a technical comparison between femtocells and WiFi in terms of architecture, operation and standards.

Disruption model for Net-on-Roads

Idea of accessing broadband services from already deployed WiFi APs while travelling at vehicular speed has gained considerable popularity among the researchers. Random location of APs makes it difficult to get continuous internet connection. As a result, a mobile node moving at vehicular speed faces periods of connections and disconnections; this intermittence is termed as “disruption”. Disruption can not be completely eradicated because it arises because of random deployment of WiFi APs. However, special algorithms may be devised to “tolerate” the available disruption. As an initial step towards this final goal, we express disruption in a typical vehicular communication session as Markov Model to ease future analysis. Our model is based on data obtained from different test runs across different areas of the city.

Extended MULE Concept for Traffic Congestion Monitoring

Wireless Sensor Networks are being recently studied to monitor real-time traffic conditions on roads and highways. Idea of using vehicles to convey information from sensors placed alongside roads to the dedicated base stations has also been under scrutiny for some time. In this paper, we argue that a sensor placed on a vehicle instead of a fixed location can effectively sense traffic congestion on the road and report it to the already available WLAN Access Points (APs) instead of the dedicated base stations. This way, instead of deploying series of base stations to collect traffic information, congestion information can be sent over the ISM links between the vehicular sensor nodes and the WLAN APs. This paper investigates, as we call it, the Extended MULE concept by using actual experimental data obtained from the test drives across the city. Our results show that adopting this idea is effective in reporting traffic congestion on the roads.

Developments and Constraints in 802.11-Based Roadside-to-Vehicle Communications

Vehicular communication has recently become popular for delivering traffic information and broadband services to the commuters. The feasibility of using the opportunistic short interval connections between vehicles and between vehicles and the roadside infrastructure is under scrutiny. The main motivation behind writing this review is that several survey works addressing inter-vehicle communications are available in literature but hardly any survey article on roadside-to-vehicle (R2V) communication is known to the authors. Here, we discuss the latest standards and protocols which can allow the use of already available WLAN infrastructure in the vehicular context. The use of roadside WLAN APs would provide the same services as those envisaged by the intelligent transportation systems using the dedicated roadside base stations. In this paper, we give an overview of the recent developments, limitations, standards and protocols that can facilitate 802.11-based R2V communication.

Throughput analysis of two-way relay networks with wireless energy harvesting capabilities

Abstract Wireless energy harvesting is an efficient way to prolong the lifetime of energy constrained networks. This paper considers a two-way amplify-and-forward (AF) based relay network, where two communicating nodes concurrently transmit their information signals to a relay node. The relay node is energy constrained, and it therefore first harvests energy from the received radio frequency (RF) signals. For energy harvesting at a relay node, we have analyzed the performance of two energy harvesting protocols: the time switching based relaying protocol (TSR), and the hybrid power-time switching based relaying protocol (HPTSR). Once the energy is harvested using one of these protocols, the relay then amplifies and forwards the received information signal towards its destination. We derive analytical expressions for the outage probability and achievable throughput for the aforementioned protocols. Our numerical results verify the analytical derivation, and show the effect of different system parameters on achievable throughput.

A discussion on software-defined handovers in Hierarchical MIPv6 networks

Mobile IPv6 (MIPv6) and its variants provide mobility support to the mobile nodes within an IP network. Hierarchical MIPv6 (HMIPv6) is an improvement on legacy MIPv6 which uses layered approach to provide low cost signaling in the environments where handovers take place frequently. Because HMIPv6 is a host-assisted handover mechanism, the wireless link of the mobile node acts as a serious bottleneck on its performance. This paper seeks to use the newly developed notion of software-defined networks (SDN) to modify HMIPv6. The idea is to use the SDN concepts during the handover process to minimize the involvement of the mobile node.

Intelligent Transport Systems

Focusing on the nuts and bolts of wireless network access for computers on board vehicles, this volume shows how in-car computerization now does much more than merely act as a glorified map-reader. Wireless communication is transforming road travel in ways previously undreamt of, allowing vehicles to talk to a wider network and monitor road conditions, potential delays and traffic congestion, all automatically. Toll payments can be made without opening the drivers window on a cold day, while vehicles might themselves take active steps to avoid collisions. It is the connection between on-board computers and wireless access points, ubiquitous in most cities now, that is a key area of research. Moving vehicles transfer their communications to new points as they progress, and this causes delays, known as handover latency. In this book, new stochastic models are developed to map the disruption when connecting to 802.11 WLAN points. It details the application of stochastic tools to analyzing communication networks, as well as previous literature on handover latency and relevant mathematical modeling. Finally, it presents a scheme for monitoring traffic congestion using WLAN connectivity. This volume will be a useful addition to the libraries both of wireless communication students and those studying probability theory.

Vehicular Communication and Sensor Networks

Ubiquitous and pervasive communication services have rapidly gained popularity over the last few years. The main objective of these services is to allow information exchange in all environments. While this information exchange conventionally takes place between hand-held devices carried by the end users, a similar information exchange between vehicles is being envisaged. Vehicular communication is becoming increasingly popular in both the research and development arenas due to its far-reaching benefits. In a nutshell, it is concerned with giving vehicles the ability to detect and convey information regarding different traffic incidents. Vehicles can send information messages either to other vehicles within close range or to the roadside base stations (BSs). This idea is not entirely new because it previously existed in the form of ?telematics.? Telematics deals with the use of telecommunications for the information exchange between remote objects. The term became known in the late 1970s but did not gain popularity because the enoromous size of communication devices was a serious limitation to their widespread use. However, with the recent developments in chip design and integrated systems, housing low-power, small-sized devices inside vehicles has become possible. Vehicular communication has now become a distinct possibility and is being looked at from research and development perspectives.

Three-Step Two-Way Decode and Forward Relay With Energy Harvesting

Radio frequency energy harvesting is being considered for realizing energy efficient relay networks. This letter focuses on decode-and-forward relaying in an energy harvesting network and develops analytical expressions of the outage probability and overall throughput. A three-step scheme has been proposed that allows the bidirectional exchange of information between two nodes via an intermediate relay. The performance of the proposed scheme has been evaluated and compared with a recent work.

Reliable cooperative scheme for public safety services in LTE-A networks

In order to enable effective public safety services in challenged environments, 3rd Generation Partnership Program is considering the use of device-to-device (D2D) communications. D2D communications can be ideal in various emergency situations where the conventional network services get suspended. We propose a D2D-based user equipment (UE) relaying process to support the out-of-range isolated UEs. The main idea is to allow UEs that have active connections with eNB to exchange data with the isolated UEs over direct D2D links. This paper proposes a mechanism that enables an ordinary UE to serve as a relay for the isolated UEs, considering the D2D link capacity and the relays radial velocity. We define the complete procedure of establishing a reliable relay link between UEs in public safety environments and analyse its performance. Copyright