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.

Method and system for wireless communication networks using cooperative relaying

Abstract: The present invention relates to relay supported wireless communication to enhance communication performance. In the wireless communication system according to the invention neighboring relay stations are arranged with substantially overlapping coverage. In the method according to the invention mobile stations makes soft association to relay stations. The mobile stations feed back the selection of relay stations and channel quality measures to the base station. The base station adapts the transmission to the relay stations based on each mobile stations reported soft associations and channel quality measures. In this way the control signaling to and from the relay stations can be very limited.

Two-Timescale Channel Estimation for Reconfigurable Intelligent Surface Aided Wireless Communications

Abstract: Channel estimation is challenging for the reconfigurable intelligent surface (RIS)-aided wireless communications. Since the number of coefficients of the cascaded channel among the base station (BS), the RIS, and the user equipment (UE), is the product of the number of BS antennas, the number of RIS elements, and the number of UEs, the pilot overhead can be prohibitively high. In this paper, we propose a two-timescale channel estimation framework to exploit the property that the BS-RIS channel is high-dimensional but quasi-static, while the RIS-UE channel is mobile but low-dimensional. Specifically, to estimate the quasi-static BS-RIS channel, we propose a dual-link pilot transmission scheme, where the BS transmits downlink pilots and receives uplink pilots reflected by the RIS. Then, we propose a coordinate descent-based algorithm to recover the BS-RIS channel. Since the quasi-static BS-RIS channel is estimated less frequently than the mobile channel is, the average pilot overhead can be reduced from a long-term perspective. Although the mobile RIS-UE channel has to be frequently estimated in a small timescale, the associated pilot overhead is low thanks to its low dimension. Simulation results show that the proposed two-timescale channel estimation framework can achieve accurate channel estimation with low pilot overhead.

MR-LEACH: Multi-hop Routing with Low Energy Adaptive Clustering Hierarchy

Abstract: In this paper, we present a Multi-hop Routing with Low Energy Adaptive Clustering Hierarchy (MR-LEACH) protocol. In order to prolong the lifetime of Wireless Sensor Network (WSN), MR-LEACH partitions the network into different layers of clusters. Cluster heads in each layer collaborates with the adjacent layers to transmit sensor’s data to the base station. Ordinary sensor nodes join cluster heads based on the Received Signal Strength Indicator (RSSI). The transmission of nodes is controlled by a Base Station (BS) that defines the Time Division Multiple Access (TDMA) schedule for each cluster-head. BS selects the upper layers cluster heads to act as super cluster heads for lower layer cluster heads. Thus, MR-LEACH follows multi-hop routing from cluster-heads to a base station to conserve energy, unlike the LEACH protocol. Performance evaluation has shown that MR-LEACH achieves significant improvement in the LEACH protocol and provides energy efficient routing for WSN.

Coordinated Multipoint Transmission with Limited Backhaul Data Transfer

Abstract: When the joint processing technique is applied in the coordinated multipoint (CoMP) downlink transmission, the user data for each mobile station needs to be shared among multiple base stations (BSs) via backhaul. If the number of users is large, this data exchange can lead to a huge backhaul signaling overhead. In this paper, we consider a multi-cell CoMP network with multi-antenna BSs and single antenna users. The problem that involves the joint design of transmit beamformers and user data allocation at BSs to minimize the backhaul user data transfer is addressed, which is subject to given quality-of-service and per-BS power constraints. We show that this problem can be cast into an l0-norm minimization problem, which is NP-hard. Inspired by recent results in compressive sensing, we propose two algorithms to tackle it. The first algorithm is based on reweighted l1-norm minimization, which solves a series of convex l0-norm minimization problems. In the second algorithm, we first solve the l2-norm relaxation of the joint clustering and beamforming problem and then iteratively remove the links that correspond to the smallest transmit power. The second algorithm enjoys a faster solution speed and can also be implemented in a semi-distributed manner under certain assumptions. Simulations show that both algorithms can significantly reduce the user data transfer in the backhaul.

A Nash game algorithm for SIR-based power control in 3G wireless CDMA networks

Abstract: We propose a new algorithm for distributed power control in cellular communication systems. We define a cost for each mobile that consists of a weighted sum of power and square of signal-to-interference ratio (SIR) error and obtain the static Nash equilibrium for the resulting costs. The algorithm requires only interference power measurements and/or SIR measurements from the base station and converges even in cases where limits on available power render the target SIRs unattainable. Examples generated using realistic data demonstrate that, in demanding environments, the Nash equilibrium power provides substantial power savings as compared to the power balancing algorithm while reducing the achieved SIR only slightly. Additional simulations show that the benefit of the Nash equilibrium power control over the power balancing solution increases as the receiver noise power or number of users in the cell increases. The algorithm has the advantage that it can be implemented distributively. An additional benefit of the algorithm is that, based on their chosen cost function, mobiles may choose to "opt out", i.e., stop transmitting, if they determine that the power required to achieve their SIR objectives is more expensive to them than not transmitting at all.