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.

Dynamic Resource Allocation for Heterogeneous Services in Cognitive Radio Networks With Imperfect Channel Sensing

Abstract: Resources in cognitive radio networks (CRNs) should dynamically be allocated according to the sensed radio environment Although some work has been done for dynamic resource allocation in CRNs, many works assume that the radio environment can perfectly be sensed However, in practice, it is difficult for the secondary network to have the perfect knowledge of a dynamic radio environment in CRNs In this paper, we study the dynamic resource allocation problem for heterogeneous services in CRNs with imperfect channel sensing We formulate the power and channel allocation problem as a mixed-integer programming problem under constraints The computational complexity is enormous to solve the problem To reduce the computational complexity, we tackle this problem in two steps First, we solve the optimal power allocation problem using the Lagrangian dual method under the assumption of known channel allocation Next, we solve the joint power and channel allocation problem using the discrete stochastic optimization method, which has low computational complexity and fast convergence to approximate to the optimal solution Another advantage of this method is that it can track the changing radio environment to dynamically allocate the resources Simulation results are presented to demonstrate the effectiveness of the proposed scheme

Interference control, sinr optimization and signaling enhancements to improve the performance of otdoa measurements

Abstract: A wireless terminal receives signaling information, pertaining to a reference signal transmission in at least one specifically designated sub frame, the signaling information including a list, the list including base station identities The terminal determines, from at least one of the base station identities in the list, the time-frequency resources associated with a reference signal transmission intended for observed time difference of arrival (OTDOA) measurements from a transmitting base station associated with said one base station identity The time of arrival of a transmission from the transmitting base station, relative to reference timing, is measured The wireless terminal can receive a command from a serving cell to start performing inter-frequency OTDOA measurement on a frequency layer containing reference signals, the frequency layer distinct from the serving frequency layer, the serving frequency layer not containing positioning reference signals The wireless terminal can perform OTDOA measurements subsequent to the reception of the command on a carrier frequency different from the serving cell carrier frequency A base station transmitter can jointly schedule a reference signal transmission from a plurality of base station transmitters for the purpose of OTD estimation enhancement, and transmit identical reference signals from the plurality of base station transmitters, the reference signals being identical both in the signal sequence and time-frequency resources used for transmission

Energy Efficiency and Spectral Efficiency Tradeoff in RIS-Aided Multiuser MIMO Uplink Transmission

Abstract: The emergence of reconfigurable intelligent surfaces (RISs) enables us to establish programmable radio wave propagation that caters for wireless communications, via employing low-cost passive reflecting units. This work studies the non-trivial tradeoff between energy efficiency (EE) and spectral efficiency (SE) in multiuser multiple-input multiple-output (MIMO) uplink communications aided by a RIS equipped with discrete phase shifters. For reducing the required signaling overhead and energy consumption, our transmission strategy design is based on the partial channel state information (CSI), including the statistical CSI between the RIS and user terminals (UTs) and the instantaneous CSI between the RIS and the base station. To investigate the EE-SE tradeoff, we develop a framework for the joint optimization of UTs’ transmit precoding and RIS reflective beamforming to maximize a performance metric called resource efficiency (RE). For the design of UT's precoding, it is simplified into that of UTs’ transmit powers with the aid of the closed-form solutions of UTs’ optimal transmit directions. To avoid the high complexity in computing the nested integrals involved in the expectations, we derive an asymptotic deterministic objective expression. For the design of the RIS phases, an iterative mean-square error minimization approach is proposed via capitalizing on the homotopy, accelerated projected gradient, and majorization-minimization methods. Numerical results illustrate the effectiveness and rapid convergence rate of our proposed optimization framework.

Fast handover algorithm for IEEE 802.16e broadband wireless access system

Abstract: IEEE 802.16e wireless metropolitan area networks refers to the new standard for broadband wireless access (BWA), which targets to support wireless Internet service up to 2 Mbps. Existing draft version of standard proposes OFDM(A)-based handover process system, which consists of network topology acquisition, scanning, initial ranging, authorization, and registration. Since various researcher groups and companies have done each part of standardization work, there exist some unclear parts and redundant processes, especially in HO process. For instance, HO initiation timing is not clearly defined and unnecessary neighboring base station (BS) scanning and association are performed before and during HO process. These redundant processes causes a long HO operation time, which makes severe degradation in system performance. In this paper, fast HO algorithm is proposed to reduce HO operation delay. Target BS estimation algorithm using mean CINR and arrival time difference reduces unnecessary neighboring BS scanning. And some redundant work during network topology acquisition and scanning process is abbreviated as well. The performance analysis validates the efficiency of the proposed algorithm.

Method and system providing RF distribution for fixed wireless local loop service

Abstract: A system and method is disclosed for distributing a radio frequency (RF) signal within a building structure or other structure not readily transparent to radio frequencies. The RF signal originates at a wireless local loop (WLL) base station and is intercepted by a main antenna on the building structure. The intercepted RF signal, which is contained in a RF bandwidth, is distributed throughout the building structure over a low bandwidth medium, e.g., in-building cabling, which has a transmission bandwidth below the RF bandwidth. In order to accomplish this, the system has a global reference oscillator for distributing a global reference tone of high stability to the entire system. Local oscillators controlled by this global reference tone deliver RF reference tones of high stability required for mixing the RF signal to obtain an intermediate frequency (IF) signal which is fed through the low bandwidth medium to remote sites. At the remote sites the RF signal recovered from the IF signal by mixing with the RF reference tone and re-transmitted, often to WLL communication units. When the WLL base station has a connection to the Public Switch Telephone Network (PSTN), the WLL communication units provide users with wireless telephone services.