Base station

About: Base station is a research topic. Over the lifetime, 85883 publications have been published within this topic receiving 1019303 citations. The topic is also known as: Mobile phone base stations & BS.

Constrained relay node placement in wireless sensor networks: formulation and approximations

Abstract: One approach to prolong the lifetime of a wireless sensor network (WSN) is to deploy some relay nodes to communicate with the sensor nodes, other relay nodes, and the base stations. The relay node placement problem for wireless sensor networks is concerned with placing a minimum number of relay nodes into a wireless sensor network to meet certain connectivity or survivability requirements. Previous studies have concentrated on the unconstrained version of the problem in the sense that relay nodes can be placed anywhere. In practice, there may be some physical constraints on the placement of relay nodes. To address this issue, we study constrained versions of the relay node placement problem, where relay nodes can only be placed at a set of candidate locations. In the connected relay node placement problem, we want to place a minimum number of relay nodes to ensure that each sensor node is connected with a base station through a bidirectional path. In the survivable relay node placement problem, we want to place a minimum number of relay nodes to ensure that each sensor node is connected with two base stations (or the only base station in case there is only one base station) through two node-disjoint bidirectional paths. For each of the two problems, we discuss its computational complexity and present a framework of polynomial time O(1) -approximation algorithms with small approximation ratios. Extensive numerical results show that our approximation algorithms can produce solutions very close to optimal solutions.

Method for establishment of the power level for uplink data transmission in a multiple access system for communications networks

Abstract: The power level for uplink data transmission in a wireless communications network utilizing an on-demand multiple access method with a fair queuing service discipline (ODMAFQ) for efficient utilization of the limited bandwidth available in the wireless network is established curing the initial access request message. The power level in a wireless network having a base station and several remote hosts is established by first transmitting a short connection request message to the base station from one of the remote hosts at an initial power level that is set relative to the nominal open loop power level. If the first remote host's transmission is unsuccessful, the power level is incremented by a power increment amount that may be predetermined, and the steps of transmitting and incrementing are repeated until the transmission from remote host to base station is successful. Finally, the power level at which transmission is successful is stored and used for further data transmission between that particular remote host and the wireless network base station.

A method and apparatus for enhancing communication reception at a wireless communication terminal

Abstract: A system provides transmit diversity with feedback to enhance the reception of communication signals at a wireless communication terminal. Multiple antennae are provided at the base station. The multiple antennae transmit multi-carrier information signals such as OFDM including pilot tones. The wireless communication terminal receives the pilot tones and performs processing on those tones to detect the relationship between the information signals transmitted from the various antennae of the base station. A feedback signal, based on the comparison of the pilot tones communicates back to the base station information about the channels of the respective transmit antennae to the terminals. The base station modifies the transmission processing associated with the various transmit antennae based upon the feedback signal. The modified processing improves the reception of the information signals at the wireless communication terminal.

Cluster head selection for energy efficient and delay-less routing in wireless sensor network

Abstract: Wireless sensor network (WSN) is comprised of tiny, cheap and power-efficient sensor nodes which effectively transmit data to the base station. The main challenge of WSN is the distance, energy and time delay. The power resource of the sensor node is a non-rechargeable battery. Here the greater the distance between the nodes, higher the energy consumption. For having the effective transmission of data with less energy, the cluster-head approach is used. It is well known that the time delay is directly proportional to the distance between the nodes and the base station. The cluster head is selected in such a way that it is spatially closer enough to the base station as well as the sensor nodes. So, the time delay can be substantially reduced. This, in turn, the transmission speed of the data packets can be increased. Firefly algorithm is developed for maximizing the energy efficiency of network and lifetime of nodes by selecting the cluster head optimally. In this paper firefly with cyclic randomization is proposed for selecting the best cluster head. The network performance is increased in this method when compared to the other conventional algorithms.

A Survey of Radio Propagation Modeling for Tunnels

Abstract: Radio signal propagation modeling plays an important role in designing wireless communication systems. The propagation models are used to calculate the number and position of base stations and predict the radio coverage. Different models have been developed to predict radio propagation behavior for wireless communication systems in different operating environments. In this paper we shall limit our discussion to the latest achievements in radio propagation modeling related to tunnels. The main modeling approaches used for propagation in tunnels are reviewed, namely, numerical methods for solving Maxwell equations, waveguide or modal approach, ray tracing based methods and two-slope path loss modeling. They are discussed in terms of modeling complexity and required information on the environment including tunnel geometry and electric as well as magnetic properties of walls.