Abstract: A repeater which is installed as measures for silent zones, which automatically compensates for a variation in a light loss caused by a difference in length among optical cables interconnecting a master device and a plurality of slave devices which are allocated and installed in an underground shopping center or the like. The master device and the slaves devices both have current detectors for detecting current values of O/E transducers which transduce received lights to electric signals. Based on the detected current values, gain control signals are applied to variable gain amplifiers to change their amplification factors so that the levels of output RF signals for transmission to a radio base station and a portable station have a prescribed value, thereby compensating for the variation in the light loss of the optical cables. The present invention greatly facilitates the installation of the repeater and additional installation of slave devices.

Abstract: When data is transferred by using a plurality of time slots, the transferring period is shortened by adopting priority to assign the required number of slots. The base station BS which accepted packet P1 generates a "BUSY" signal and an echo at the final portion of the first time slot TS which begins at time t4. The base station BS, recognizing that there is a packet following the packet P1, generates a "RESERVED" signal at the final portion of the time slot TS which begins at time t5. The mobile station MS-A learns that the first time slot is assigned by recognizing the "BUSY" signal and the echo, and that the second time slot is also assigned by recognizing the "RESERVED" signal. Therefore, the first and second time slots are used successively for fast transferring.

Abstract: Two beams with equiangular spacing are formed at a single antenna face, and multiple beams are generated by combining a plurality of such faces. This makes it possible to reduce the size of an antenna device and to decrease the wind load sustained by an antenna, whereby it becomes possible to mount many antennas on a single supporting structure and to achieve substantial weight reduction of a supporting structure.

Abstract: When an incoming call corresponding to a communication number PID takes place in a switching station, the switching station retrieves user-intrinsic information UK and an incoming-communication registered terminal identification number SID and sends the communication number PID to a communication terminal. When the communication terminal replies, the switching station generates a random number R and sends it to the communication terminal. In addition, the switching station generates a cryptical key K=F (R, UK) corresponding to the user-intrinsic information UK and the random number R. The communication terminal generates a cryptical key K=F (R, UK) corresponding to the received random number R and the user-intrinsic information UK that is input by the user. The switching station and the communication terminal encrypt the communication information corresponding to the cryptical key K and decrypt received encrypted communication information.

Abstract: CDMA mobile communication method and system for realizing an autonomous distributed control of radio channel allocation, a synchronization control for a smooth establishment/switching, and a VOX control for a capacity increase are provided. At either one station of each base station and the mobile station, one of a plurality of prescribed short spread codes is selected, and a data sequence to be transmitted is spread by using the selected short spread code and a prescribed long spread code and then transmitted, while at another one station, the data sequence before spreading is reproduced and received by despreading the data sequence from that either one station by using the selected short spread code and the prescribed long spread code.

Abstract: A mobile communication system using an autonomous distributed type dynamic channel allocation scheme, in which each base station manages allocation priority levels for the available radio channels according to past records of channel use for each radio channel, and updates the allocation priority level of each radio channel by weighting past allocation accept/reject judgement results for each radio channel with weight factors which vary according to time intervals of the past allocation accept/reject judgement results from a current time. The mobile stations can be grouped into N groups according to states of the mobile stations and N sets of allocation priority levels for each radio channel in correspondence to these N groups can be managed at each base station. The thresholds for grouping the mobile stations can be determined according to past records of states of the mobile stations.

Abstract: In a transmission circuit, part of the output signal of the transmission circuit is diverted by an output monitor circuit and subjected to envelope detection by an output detector circuit. The output signal of the output detector circuit is inputted to a peak hold circuit successively holding the peaks of the input signal, so that varying amplitude components are removed, and a DC value is detected. An error detector circuit compares the detected value with a reference signal from a reference signal generator circuit, and the error signal is used as a gain control signal to control the gain of a power amplifier circuit.

Abstract: In a reference signal adaptive estimation part 15, a received signal sample z.sub.n-2 at time (n-2) is phase rotated by M states .DELTA..phi..sub.n-1 at time (n-1), and the phase-rotated signal and a received signal sample z.sub.n-1 are used to calculate the following linearly predicted value of the received signal sample at time (n-1) that contains a fading variation at time n,z.sub.n-1 =(1+.lambda.)z.sub.n-1 -.lambda.z.sub.n-2 exp(j.DELTA..phi..sub.n-1).A square error between a signal phase-rotated .DELTA..phi..sub.n from the linearly predicted value z.sub.n-1 and a received signal sample z.sub.n is calculated as a branch metric in a branch metric calculating part 16 and this branch metric is used for decoding in a Viterbi decoding part 17. A prediction coefficient .lambda.

Abstract: A repeater improving the effect of a RAKE reception. A received signal from a base station parallelly passes a first path including a first delay circuit and a second path including no delay circuit, and is transmitted to a mobile station. A received signal from the mobile station parallelly passes a third path including a second delay circuit and a fourth path including no delay circuit, and is transmitted to the base station. The delay time of the delay circuits are set at one chip interval or more of a spreading code. This forcedly produces multipath waves which are resolvable by a RAKE receiver. The RAKE receiver estimates amplitudes of desired wave components for individual delayed waves, performs weighting of the respective delayed wave components from detectors by using the estimated amplitudes, and makes symbol decision in terms of the combined weighted signal.

Abstract: In a mobile communication network, a mobile unit location register ML and a subscriber location register SL are provided. In the mobile unit location register the mobile location of a mobile unit MT is registered, whereas in the subscriber location register a mobile unit MT selected by each subscriber SB as a terminal for call terminating use is registered. Upon receiving a terminating call for a subscriber, a switching center SW reads out, from the subscriber location register SL, an identifying number TID of the mobile unit registered by the subscriber SB as a terminal for call terminating use and uses the mobile unit identifying number TID to read out the mobile location of the mobile unit MT from the mobile unit location register ML, thereafter sending the terminating call to the registered mobile unit of the read-out mobile location.

Abstract: A correlation detector is provided which can establish initial acquisition quickly, and achieve high accuracy tracking by extracting crosscorrelation components in a receiver for CDMA communication, and a communication system using the correlation detector is also provided. During the initial acquisition, a received signal 21 is supplied to a matched filter 43. When an acquisition decision circuit 45 decides that the matched filter 43 detects the acquisition, it controls a switching circuit 42 to supply the received signal 21 to multipliers 47 and 48, and resets a VCCG 29 and a spreading code replica generator 30. After establishing the acquisition, a received spreading code is quasicoherent detected, and the detected spread signal is multiplied by a phase advanced replica and a phase retarded replica. Correlation detection signals are produced from the products, and squared components of the correlation detected signals are generated, summed in the opposite phase, and averaged along the time axis.

Abstract: An ARQ data transmission scheme in which the overhead due to the ARQ control data is reduced to resolve the problem of the throughput deterioration. The error correction code for the original data is used for each re-transmission block or sub-block, and the block or sub-block corresponding to each re-transmission block or sub-block is found by carrying out the error correction operation with respect to each block or sub-block to be re-transmitted which is stored in the memory, so that there is no need to include the block or sub-block number for identifying each block or sub-block in the re-transmission frame, and consequently the ratio of the ARQ control data with respect to the transmission data can be made relatively smaller and the throughput can be improved.

Abstract: A transmission power control method is disclosed for controlling transmission power of radio communications in a CDMA system. The transmission power of a first transmitted signal transmitted from a first station is determined by a transmission power control signal contained in a second transmitted signal sent from a second station. The first station receives the second transmitted signal in the form of convolutional codes, and decodes it by using a first Viterbi decoder and a second Viterbi decoder. The first and second Viterbi decoders includes path memories with the path history length of different first predetermined lengths. The transmission power control signal contained in the second transmitted signal is extracted from the output of the second Viterbi decoder, whereas the other information data is obtained from the output of the first Viterbi decoder. The first station controls the transmission power of the first transmitted signal on the basis of the extracted transmission power control signal.

Abstract: A received signal sample sequence is inversely modulated by a symbol sequence forming the trellis state at the immediately preceding time, by which a reference signal is generated. This reference signal and the inner product of the received signal sample at the current time and a candidate symbol phase are used as a branch metric to make a sequence estimation by the Viterbi algorithm.

Abstract: A rod antenna element is connected at its lower end to one end of a coaxial impedance converter, the other end of which is connected to a feeder. A coil antenna element is capacitively coupled to the rod antenna element to provide a double resonance characteristic. When held at its retracted position, the rod antenna element, inserted in an outer conductor of the coaxial impedance converter, may preferably form an inner conductor larger in diameter than that when the rod antenna element is at its extended-out position, and the rod antenna element is connected to a coil antenna element with a low impedance.

Abstract: Transmission quality and throughput are improved when communication is carried out using fixed-length packets in wire circuits between radio base stations and a mobile switching center in mobile radio communications systems. Low bit-rate digital information signals are converted to short packets by a plurality of information data assembly/disassembly circuits provided in parallel. A plurality of these short packets are transmitted after being inserted into a long fixed-length packet by means of a fixed-length packet assembly/disassembly circuit, and a plurality of short packets are extracted from the fixed-length packet and then restored to the low bit-rate digital information signals by information data assembly/disassembly circuits. This enables high throughput, economical communication paths to be constructed.

Abstract: A transmission power control method of a spread-spectrum communication system which determines transmission power in accordance with a transmission power control bit. The transmission power control bit is extracted at a base station from a signal sequence obtained by receiving a signal transmitted from a mobile station, and by despreading and demodulating the received signal. When the same value of the transmission power control bit is consecutively received, the transmission power of the base station is controlled in accordance with transmission power control quantities which are predetermined in accordance with the consecutive number of receptions of the same value of the transmission power control bit. This is because the consecutive receptions of the same value of the transmission power control bit suggests that the received power of the other party (the mobile station in this case) changes greatly.

Abstract: A mobile station measures the field intensity and bit error rate of a downlink radio wave from a base station at each measurement timing and reports the measured results to the base station. Upon receiving the measured results from each mobile station, the base station compares the measured results with a reference characteristic to determine if they are abnormal or not. The base station acquires the determined results of the measured results for a fixed period of time and statistically processes them to judge the state of interference.

Abstract: To prevent a coefficient vector for a modulated wave candidate of repeated identical codes from diverging, an error calculating part (36) calculates the difference between a vector X(i) with elements of input signals x(i) at N successive times and a vector Y.sub.m (i) of N replica signals y.sub.m (i) received from a transversal filter (34) to obtain an error vector E.sub.m (i), the square of the norm of which is supplied to a maximum likelihood sequence estimating portion (31), when signal estimation is carried out. In addition, a code sequence candidate {a.sub.m } is produced and a corresponding modulated wave candidate s.sub.m is generated. The filter (34) calculates the inner product of the modulated wave candidate s.sub.m and the coefficient vector W.sub.m (i-1) corresponding to each state to produce y.sub.m (i). W.sub.m (i-1) of each state is updated to W.sub.m (i) using an inner product vector of a generalized inverse matrix produced from s.sub.

Abstract: A multipath component detector detects the correlation between a received signal and a reference signal in a training period of the received signal and estimates and outputs the multipath received component levels at a plurality of timing points. A component ratio calculator calculates the ratio of each received component to the overall received power. By this, the level ratio of a specified received component can be detected. Power dissipation can be minimized by switching the detector to a differential detector or an adaptive equalizer in accordance with the result of the delay spread measurement.