A method and apparatus for measuring a change in the insertion loss of a transmission line in a communication system is disclosed. The method provides feeder cable insertion loss detection in a transmission system without interfering with normal operation. The method includes injecting a non-interfering signal at a predetermined frequency onto a cable providing normal operating signals to a narrowband device at a predetermined frequency, measuring the amplitude of the injected signal, measuring the amplitude of a reflected signal, the injected signal being reflected by the narrowband device and processing the amplitude of the injected signal and the amplitude of the reflected signal to derive a current insertion loss for the cable. In addition, the method further includes comparing the current insertion loss to a prior insertion loss and determining the cable to be defective when the current insertion loss differs from the prior insertion loss by a predetermined amount and replacing the cable when the current insertion loss differs from the prior insertion loss by the predetermined amount. The injecting further includes selecting a signal for injection having a frequency and power that does not interfere with the normal operating signals and which causes the signal to reflect back from the narrowband device. The frequency of the selected signal for injection causes the narrowband device to appear to the selected signal for injection as a short or an open. The narrowband device is an antenna, a low noise amplifier, a power amplifier, a filter or a RF-to-light converter for a fiber optic distribution network.

An apparatus for testing cellular base stations is provided. A base station tester is connected to a control link between the base station controller and the cellular base station to receive the fixed signal. The fixed link signal contains a voice channel and a control channel that may be selectively monitored by the base station tester. The base station tester is also connected to the radio frequency (RF) output of the cellular base station to receive the RF signal from the cellular base station. Both the RF signal and the fixed link signal are obtained in a non-invasive manner such that the cellular base station may remain in service during the testing process. By monitoring the fixed link directly, the base station tester may evaluate directly the reaction of the cellular base station with its RF signal to the commands received from the fixed link to perform parametric transmitter measurements. The base station tester may further compare the information received from the voice channel with the information contained in the RF signal to perform parametric receiver measurements.

Method and apparatus are described for controlling base station transmit power (downlink) to a mobile station during soft diversity handover. The present invention adjusts downlink power of the ratio between downlink transmit powers of all of the involved base stations is equal to the received signal strengths from the mobile stations at each of the involved base stations.

The invention concerns a method of power regulation in a radio system including at least two transmitters, e.g. base transceiver stations, transmitting at the same frequency and receivers, e.g. mobile stations, which have set up a radio communication with the former. In the method according to the invention, the results of measurements of co-channel adjacent transmitter signals are used, besides the results of measurements of the radio communication to be relayed, in making the power regulation decision. From the results of measurements of adjacent transmitter signals to be transmitted with the monitored radio communication at the same frequency and in the same time slot, an estimate is determined of that interference caused to the radio communication, which is to be compensated for by a regulation of the transmission power of the desired signal.

Disclosed is a device (200) and a method for measuring a receive sensitivity of a communication system having a transmit and receive path and a receive-only path, like a base station (100) employing space diversity by means of one transmit and receive antenna (111) and an additional receive antenna (121). A terminal (220) is connected to the transmit and receive path and to the receive-only path by means of a first (112) and a second coupler (122) and a first (213a) and a second transmitter (215a) whereby the input signals are combined by a combiner (211) to a single signal fed to the terminal (220). Furthermore, the terminal (220) selectively transmits a test signal at selected frequencies to a receive sensitivity measuring path by means of a first (212) and a second (214) switch and a first (213b) and a second (215b) receiver in order to measure the receive sensitivities of the transmit and receive path and the receive-only path of the communication system and to measure the performance of the corresponding communication system.