The remarkable growth of wireless data traffic in recent times has driven the need to explore suitable regions in the radio spectrum to meet the projected requirements. In pursuance of this, millimeter wave communications have received considerable attention in the research fraternity. Due to the high path and penetration losses at millimeter wavelengths, antenna beamforming assumes a pivotal role in establishing and maintaining a robust communication link. Beamforming for millimeter wave communications poses a multitude of diverse challenges due to the large channel bandwidth, unique channel characteristics, and hardware constraints. In this paper, we track the evolution and advancements in antenna beamforming for millimeter wave communications in the context of the distinct requirements for indoor and outdoor communication scenarios. We expand the scope of discussion by including the developments in radio frequency system design and implementation for millimeter wave beamforming. We explore the suitability of millimeter wave beamforming methods, both, existing and proposed till midyear 2015, and identify the exciting new prospects unfolding in this domain.

Beamforming for Millimeter Wave Communications: An Inclusive Survey

A wireless telecommunication system comprises base stations for communicating with terminal devices. One or more base stations support a power boost operating mode in which a base station's available transmission power is concentrated in a subset of its available transmission resources to provide enhanced transmission powers as compared to transmission powers on these transmission resources when the base station is not operating in the power boost mode. A base station establishes an extent to which one or more base stations in the wireless telecommunications system support the power boost operating mode conveys an indication of this to a terminal device. The terminal device receives the indication and uses the corresponding information to control its acquisition of a base station of the wireless telecommunication system, for example by taking account of which base stations support power boosting and/or when power boosting is supported during a cell attach procedure.

Telecommunications apparatus and methods

Aspects of the subject disclosure may include, for example, receiving, by each of a plurality of receivers, one of a plurality of electromagnetic waves, each electromagnetic wave of the plurality of electromagnetic waves guided by a different one of a plurality of twin-lead transmission lines, each twin-lead transmission line sharing a wire, and each electromagnetic wave of the plurality of electromagnetic waves including a different one of a plurality of communication signals, and obtaining, by each of the plurality of receivers, one of the plurality of communication signals. Other embodiments are disclosed.

Method and apparatus for exchanging communication signals

Aspects of the subject disclosure may include, for example, receiving, by a network element of a distributed antenna system, a reference signal, a control channel and a first modulated signal at a first carrier frequency, the first modulated signal including first communications data provided by a base station and directed to a mobile communication device The instructions in the control channel direct the network element of the distributed antenna system to convert the first modulated signal at the first carrier frequency to the first modulated signal in a first spectral segment The reference signal is received at an out of band frequency relative to the control channel Other embodiments are disclosed

Method and apparatus for use with a radio distributed antenna system having an in-band reference signal

Aspects of the subject disclosure may include, for example, receiving, by a network element of a distributed antenna system, a reference signal and a first modulated signal at a first carrier frequency, the first modulated signal including first communications data provided by a base station and directed to a mobile communication device. The element converts the first modulated signal at the first carrier frequency to the first modulated signal in a first spectral segment based on an analog signal processing of the first modulated signal and utilizing the reference signal to reduce distortion during the converting. The network element wirelessly transmits the first modulated signal at the first spectral segment to the mobile communication device. Other embodiments are disclosed.

Method and apparatus for use with a radio distributed antenna system

A method and apparatus may provide multi-user parallel channel access (MU-PCA) and/or single-user parallel channel access (SU-PCA) using transmit and/or receive with symmetrical bandwidth, in the downlink (DL), uplink (UL), or combined DL and UL. SU-PCA and MU-PCA may support unequal modulation and coding schemes (MCS) and unequal transmit power. Medium access control (MAC) layer, Physical layer (PHY), and mixed and PHY layer methods and procedures may support UL, DL and combined UL and DL SU-PCA and MU-PCA using transmit and/or receive with symmetrical bandwidth. MU-PCA and/or SU-PCA may also be supported by MAC and PHY layer designs and procedures for downlink, uplink and combined uplink and downlink using transmit/receive with asymmetrical bandwidth.

Multi-user parallel channel access in wlan systems

WTRUs, access points (APs) and methods thereon are disclosed. A method on a WTRU may include receiving a message from an AP that comprises a beamformee capability element; sending a second message to the AP that comprises a beamformer capability element; and receiving, from the AP, a third message in response to the second message that indicates a group to which the WTRU is assigned. The group may be based on the beamformer capability element and the group may indicate UL transmission information to be used by the WTRU. A method on an AP may include determining a group for multiple WTRUs based on a received beamformer capability element. A method on a WTRU may include sending to an AP a message with a low overhead preamble for UL MU-MIMO. The low overhead preamble may include LTFs that enable the AP to distinguish the WTRU from other WTRUs.

Multi-user multiple input multiple output communications in wireless local area networks and wireless transmit and receive units

A method, apparatus, system, and computer readable medium may be used to perform beamforming. The method may include a first communication device sending a first plurality of beamforming training frames to a second communication device using a first beamforming weight vector; the first communication device receiving from the second communication device a second beamforming weight vector; and the first communication device sending a second plurality of beamforming training frames to the second communication device using the second beamforming weight vector. The apparatus, method, system, and computer readable media may use spatial diversity with beam switching, spatial diversity with a single beam, weighted multipath beamforming training, single user spatial multiplexing, and beamforming training for beam division multiple access (BDMA).

Beamforming methods and methods for using beams

A method and apparatus is described herein for performing loop power control and transmission power control (TPC) in a wireless network. Described herein are methods including using separate power control loops for communication with an entire wireless network and for point-to-point (P2P) transmissions and separate power control loops for omni-directional and directional beamformed transmissions. Also described herein are methods and apparatuses for requesting clear channel assessment (CCA) measurements and adjusting CCA thresholds and transmission power based on the reported measurements. Methods and apparatuses are also described wherein access points (APs) coordinate transmission power to reduce interference with each other and to determine optimal transmission power to each mobile station (STA).

Power control methods and procedures for wireless local area networks

Methods for WiFi beamforming, feedback, and sounding (WiBEAM) are described. Codebook based beamforming feedback signaling and sounding mechanisms for use in wireless communications are disclosed. The methods described herein improve the feedback efficiency by using Givens rotation based decompositions and quantizing the resulting angles of the Givens rotation based decompositions using a range from a subset of [0, 2π]. Feedback may also be divided into multiple components to improve feedback efficiency/accuracy. Time domain beamforming reports for taking advantage of channel reciprocity while still taking into account practical radio frequency (RF) channel impairments are also described. Beamforming feedback that prioritizes the feedback bits in accordance with the significance of the bits is also disclosed. A preamble structure to enable the use of smoothing methods for improved channel estimation, codebook designs that may be used for codebook based beamforming feedback, and multi-resolution explicit feedback are disclosed as well.

Hanqing Lou

Papers

Multi-user parallel channel access in wlan systems

Multi-user multiple input multiple output communications in wireless local area networks and wireless transmit and receive units

Beamforming methods and methods for using beams

Power control methods and procedures for wireless local area networks

Method for WiFi beamforming, feedback, and sounding (WiBEAM)