A network node is connected to a plurality of antenna nodes that are located along a path where a plurality of wireless communication devices are located. The antenna nodes are controlled (302) to maintain reception radio lobes substantially along the path such that the wireless communication devices can communicate with the network node via the reception radio lobes. From a detected (304) radio frequency signal, a determination (306) is made that a UE belongs to a group of UEs having common Doppler radio frequency characteristics. This determination then enables processing (308) of the received signal involving the common Doppler characteristics.

Aspects of the subject disclosure may include, for example, a coupling device including a first antenna that radiates a first RF signal conveying first data; and a second antenna that radiates a second RF signal conveying the first data from the at least one transmitting device. The first RF signal and second RF signal form a combined RF signal that is bound by an outer surface of a transmission medium to propagate as a guided electromagnetic wave substantially in a single longitudinal direction along the transmission medium. Other embodiments are disclosed.

Aspects of the subject disclosure may include, for example, a coupling device including a first antenna that radiates a first RF signal conveying first data; and a second antenna that radiates a second RF signal conveying the first data from the at least one transmitting device. The first RF signal and second RF signal form a combined RF signal that is bound by an outer surface of a transmission medium to propagate as a guided electromagnetic wave substantially in a single longitudinal direction along the transmission medium. Other embodiments are disclosed.

A radio communication apparatus capable of alleviating a burden in setting a transmission format and suppressing increases in the scale of the apparatus. In this apparatus, space multiplexing adaptability detection section detects space multiplexing transmission adaptability for divided bands obtained by dividing a communication band to which Ns subcarrier signals belong in multicarrier transmission and to which a plurality of subcarrier signals belong, and outputs the detection results. Transmission format setting section sets a transmission format when carrying out radio transmission based on the detection results from space multiplexing adaptability detection section.

A radio communication apparatus capable of alleviating a burden in setting a transmission format and suppressing increases in the scale of the apparatus. In this apparatus, space multiplexing adaptability detection section detects space multiplexing transmission adaptability for divided bands obtained by dividing a communication band to which Ns subcarrier signals belong in multicarrier transmission and to which a plurality of subcarrier signals belong, and outputs the detection results. Transmission format setting section sets a transmission format when carrying out radio transmission based on the detection results from space multiplexing adaptability detection section.

Method and apparatus for time or frequency synchronization of radio signals transmitted by user terminals in communication with a gateway through a satellite is provided. The satellite may be part of a non-synchronous satellite communication system, such as a low-earth orbit (LEO) satellite communication system for data, voice or video communications. Times of transmission of return link radio signals from the user terminals may be adjusted such that the signals arrive at the satellite or at the gateway without large time delay differentials. Carrier frequencies of return link radio signals transmitted from the user terminals may be adjusted such that the signals arrive at the satellite or at the gateway without large frequency offset differentials.

Method and apparatus for time or frequency synchronization of radio signals transmitted by user terminals in communication with a gateway through a satellite is provided. The satellite may be part of a non-synchronous satellite communication system, such as a low-earth orbit (LEO) satellite communication system for data, voice or video communications. Times of transmission of return link radio signals from the user terminals may be adjusted such that the signals arrive at the satellite or at the gateway without large time delay differentials. Carrier frequencies of return link radio signals transmitted from the user terminals may be adjusted such that the signals arrive at the satellite or at the gateway without large frequency offset differentials.

A method for transmitting a reference signal to a user equipment at a base station in a wireless communication system is disclosed. The method includes transmitting a control channel and the reference signal having a first pattern for the control channel to the user equipment and transmitting a data channel and the reference signal having a second pattern for the data channel to the user equipment, wherein reference signal density of the second pattern is determined based on a coherence time of the data channel, and the first pattern includes the second pattern.

A method for transmitting a reference signal to a user equipment at a base station in a wireless communication system is disclosed. The method includes transmitting a control channel and the reference signal having a first pattern for the control channel to the user equipment and transmitting a data channel and the reference signal having a second pattern for the data channel to the user equipment, wherein reference signal density of the second pattern is determined based on a coherence time of the data channel, and the first pattern includes the second pattern.

The invention involves using Doppler shift to locate a leak of a signal from an HFC network. The leaked signal includes a component having a nominal frequency. The invention comprises: (a) moving along a drive route in the area of the network; (b) recording a speed at a number of drive-route points along the drive route; (c) at each point, receiving the component at a received frequency; (d) for each point, measuring the received frequency; (e) for each point, determining a measured Doppler shift from a difference between the received and nominal frequencies; (f) estimating a zero Doppler shift and a zero Doppler shift point based on the measured Doppler shifts; and (g) estimating the leak location based on the estimated zero Doppler shift point.