Base Stations In Cellular Networks Research Articles

An optical beam former for smart antennas in mobile broadband communication

The design and simulation of a Micro Electro Mechanical Systems (MEMS)-based Optical Signal Processing (OSP) beam former for cellular network base stations are reported in this paper. The modulated optical signal destined for a mobile terminal is split into eight equal-intensity signals. Each signal is weighted by controlling the phase and amplitude using a pair of micromirrors driven by electrostatic comb drive actuators. The processed optical signal is heterodyned with a phase-locked local optical signal. The resulting weighted microwave signal is then fed to the corresponding element of the 1 × 8 antenna array. The radiation patterns of the proposed multibeam-forming network are simulated using MATLAB and SIMULINK.

Distributed Algorithm for Real Time Cooperative Synthesis of Wireless Cell Coverage Patterns

A real time fully distributed algorithm that would allow base stations (BSs) in cellular networks to autonomously and cooperatively find the wireless coverage pattern to optimize network performance is described. An antenna system that can change the radio frequency (RF) coverage is assumed at each base station. Simulations based on Mobile WiMAX technology show the effectiveness and robustness of the approach.

Robust Mobile Location Estimator with NLOS Mitigation using Interacting Multiple Model Algorithm

A Kalman-based interacting multiple model (IMM) smoother is proposed for mobile location estimation with the time of arrival (TOA) measurement data in cellular networks to meet the Federal Communications Commission (FCC) requirement for phase 2. In this study, the line-of-sight (LOS) and non-line-of-sight (NLOS) conditions in cellular networks are considered as a Markov process with two interactive modes. Then we propose a Kalman-based IMM smoother to accurately estimate smooth range between the corresponding base station (BS) and mobile station (MS) in cellular networks. It is shown that the proposed mobile location estimator can efficiently mitigate the NLOS effects of the measurement range error even when the corresponding BS changes the condition between LOS and NLOS. Simulation results demonstrate that the performance of the proposed Kalman-based IMM smoother is improved significantly over the FCC target in both fixed LOS/NLOS and LOS/NLOS transition conditions

An Efficient Paging Strategy Based on Paging Agents of Base Stations in Cellular Mobile Networks

We propose a new paging strategy to reduce paging cost by adding paging agents at base stations. When a mobile-terminated call occurs, the base stations look up the paging agents to determine if terminal paging is actually to be made. An analytical model based on a Markov chain is used to evaluate the performance of the proposed strategy. The numerical results show that the proposed strategy significantly reduces the paging cost compared with the simultaneous paging strategy.

Software defined radio architecture for cellular networks base stations: TheSunbeam project

With the arrival of 3G radio mobile communications standards namelyUmts, new requirements arose for the wireless cellular networks. They concern the quality of the transmissions, the compatibility with pre-existing 2G networks and between different 3G networks and of course the increasing bandwidth to bring new high data rate demanding services through IP connections. TheSunbeam project was at the convergence of two key enabling technologies for 3G: software radio and smart antennas. Software radio appears to be an unavoidable approach to fulfil these specifications, but it needs to be used with new hardware architectures designed to support it.Acts European projectSunbeam just covered partially this subject as it concerned flexible multi-standard smart CBTS architecture study in the context of the migration of European networks from 2G (Gsm, Dcs 1800) to 3 G (Acts/Fdd, Acts/Tdd), concentrating on the physical layer. Digital smart antennas techniques were central in the scope ofSunbeam, since they are to bring the decisive performance improvements 3G transmissions require. This paper summarises the essential results achieved within the project and makes an attempt to establish global specifications for CBTS architecture design to achieve the flexibility, the reconfigurability and the scalability needed to implement software radio.

Adjacent-Cell Interference in Direct-Sequence CDMA Forward Traffic Channels

Each transmission from a base station in a mobile cellular direct-sequence CDMA network is a source of interference for the receivers in the mobile handsets that are operating in adjacent cells. This interference can limit the capacity of the forward traffic channels. The effect of adjacent-cell interference on the performance of the handset receivers is evaluated for a mobile cellular CDMA network that employs quadriphase-shift-key spreading, convolutional coding, and soft-decision decoding. It is demonstrated that acceptable performance may not be possible for a fully loaded cellular network. Of particular interest in this paper are cellular networks in which the base stations are mobile and must be interconnected by wireless communication links. Such networks are important for military applications and certain civilian emergency communications services.

GaAs MMICs for cellular and wireless networks base stations

The considerable growth of the radiocommunication markets is undoubtedly the major event of the 90's for the semiconductor industry worldwide. In a first stage, integrated circuit manufacturers have concentrated their efforts towards the handheld / mobile terminals segment for several reasons. On the one hand, the market size is much more attractive (the most conservative studies forecast up to 37 million subscribers in the year 2000 only for the GSM services). On the other hand, the handheld system requirements more naturally call for high integration to meet the customer demand for lower weight and more compact designs as well as to allow the lowest cost mass production of this consumer product. The base stations segment has different characteristics in terms of performance, constraints and market size but however represents a significant opportunity for RF integrated circuits. This paper reviews the RF specifications of GSM/DCS and DECT base stations considering the base to mobile and base to base communication links, and highlights several products that address these particular needs.

The spectrum efficiency of a base station antenna array system for spatially selective transmission

In this paper we investigate the spectrum efficiency gain using transmitting antenna arrays at the base stations of a mobile cellular network. The proposed system estimates the angular positions of the mobiles from the received data, and allows multiple mobiles to be allocated to the same channel within a cell. This is possible by applying a transmit scheme which directs nulls against co-channel users within the cell. It is shown that multiple mobiles per cell is an efficient way of increasing capacity in comparison with reduced channel reuse distance and narrow beams (without directed nulls). The effect of the spatial spread angle of the locally scattered rays in the vicinity of the mobile is also investigated. >