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.

Abstract: A code sequence generator having a register for holding n-bit code, and a calculation circuit for performing matrix calculation on the content of the register, and sequentially generating a code sequence by feeding back the calculation results to the register. The matrix which is set in the calculation circuit is changed by selectively reading a matrix from a memory circuit that stores precalculated matrices. This makes it possible to set a desired register state in a short time even if the desired code sequence is very long, and to generate any code sequences without changing the rate of a clock signal.

Abstract: A transmission power control method of a mobile station in a CDMA (Code Division Multiple Access) system which primarily controls transmission power of the mobile station by using a closed loop control which enables high accuracy power control. When the received power at the base station of a signal from the mobile station suddenly increases owing to the state of buildings surrounding the mobile station, the transmission power of the mobile station must be quickly reduced to prevent the interference to other mobile stations. The mobile station measures an average value of the received power per transmission power control period of a desired signal from the base station, and detects the difference .DELTA.RSSI between the current average value and that of one of the previous transmission power control periods. If .DELTA.RSSI exceeds a reference power difference .DELTA.P.sub.th, transmission power P.sub.T corresponding to .DELTA.

Abstract: An up-link channel assignment scheme for cellular mobile communications systems employing multibeam antennas with beam selection, in which a channel that is selected from among all variable channels in the same frequency band may be assigned to each of the antenna beams in a base station for communications. Channel selection for a base station takes place independently of that for other cells, such that the process is autonomous. Channel selection is based upon an estimate of the signal-to-interference power ration ("SIR") in which a channel having the smallest SIR estimate that is larger than or equal to a given threshold value is chosen. Alternatively, a channel having the largest SIR estimate is selected.

Abstract: A CDMA communications method capable of multiplex transmission of data over a wide range from a low rate to high rate such as image data without a considerable increase in a circuit scale. A fundamental transmission rate is determined, for example, at 32 kbps, a rate higher than 8 kbps conventionally used. The data whose transmission rate is equal to the fundamental transmission rate is transmitted in frames including no vacant portion. Data whose transmission rate is lower than the fundamental transmission rate (16 kbps, for example) is transmitted in frames including vacant portions. The vacant portions are not transmitted. This makes it possible to receive data through other channels during a time period associated with the vacant portions. Data of a higher transmission rate, 128 kbps, for example, can be multiplexed and transmitted through four channels using different spreading codes.

Abstract: Mobile stations randomly set delay amounts for each message to be sent, on the basis of the timing of a symbol received from a base station, and delay transmission signals for time intervals corresponding to the delay amounts. The base station 11 despreads signals received from the mobile stations to extract basic symbol timing for each mobile station and, at the thus extracted timing, takes each despread output into the corresponding demodulator for demodulation.

Abstract: A base station and a mobile station in a mobile communication system capable of reducing interference among mobile stations and increasing a subscriber capacity of the system. The base station has a unit for measuring a measurement value for at least one of a receiving level and an interference ratio level of the mobile station transmission signals, and a unit for producing a mobile station transmission power control data specifying a mobile station transmission power required in adjusting the measurement value to a target level according to a number of base stations simultaneously in communication with the mobile station.

Abstract: A switching center 30 comprises a memory part M2, a memory part M3, and a memory part M4. The memory part M2 stores a terminating terminal number corresponding to and registered by each subscriber. The memory part M3 stores idle/busy information corresponding to each terminal. The memory part M4 stores idle/busy information corresponding to each subscriber. When a subscriber 11.sub.1 makes a call at a terminal 12.sub.2, the switching center 30 determines whether the idle/busy information for the subscriber 11.sub.1 stored in the memory part M4 is idle or busy. When the idle/memory information represents idle, the switching center 30 refers to the idle/busy information for the terminal 12.sub.2 stored in the memory part M3. When this idle/busy information represents idle, the switching center 30 reads out the terminal number of a terminating terminal of a terminating subscriber stored in the terminating terminal memory part M2 and performs an outgoing call connection process.

Abstract: In a mobile communication system which uses a code division multiple access (CDMA) scheme for communications between a base station and a plurality of mobile stations, the base station has a transmitting device in which a plurality of information sequences S1 through Sn are respectively spread by multipliers 11 through 1n with a common spreading code from a spreading code generator circuit 10, the spread codes are provided to transmitting timing control circuits 21 through 2n and then added by an adder 30 to perform transmitting timing offset multiplexing and then the spread signals are transmitted to the mobile stations at different transmitting timing. The mobile stations each have a receiving device which receives that one of the transmitted signals which was transmitted at timing predetermined for the mobile station and despreads the received signal with the same spreading code as that used in the transmitting device, thereby reconstructing the original information sequence concerned.

Abstract: A transmission power control method for a CDMA system including the steps of calculating an actual SIR (Signal-to-Interference Ratio) of a desired signal; deciding whether the actual SIR is greater than a predetermined reference SIR which satisfies a predetermined conununication quality; forming a transmission power control bit on the basis of a result of deciding; inserting the transmission power control bit periodically into a forward frame, which steps are performed at the base station, and steps of calculating tentative reverse transmission power in accordance with the transmission power control bit in the forward frame; deciding reverse transmission power such that the reverse transmission power is made equal to the tentative reverse transmission power when the tentative reverse transmission power is less than a predetermined maximum transmission power, but otherwise made equal to the predetermined maximum transmission power; and transmitting a signal from the mobile station to the base station at the re

Abstract: A method of communicating a speech signal over a communication medium which utilizes VOX (Voice Operated Transmitter) control, and a speech signal transmitting unit and a speech signal receiving unit used in said method. The speech signal includes at least one speech-active duration in which actual speech exists and one silent duration in which no actual speech exists. At a transmitting side, the speech signal is analyzed for each of successive frames thereof to determine whether each frame is in the speech-active duration, and is coded for each of successive frames thereof to produce a series of successive coded data of the speech signal. Then, in response to the detection of a speech starting frame of the speech-active duration, the coded data of the speech starting frame is switched to a preamble, and the preamble and the successive coded data subsequent to the speech starting frame are transmitted in the form of a series of successive frames.

Abstract: In a radio receiver for receiving a radio signal, a counter (32) counts an eventual intermediate frequency of an amplified signal based on a reference signal as a count datum. A frequency controller (27) controls a reference frequency of the reference signal according to the count datum. A reference oscillator (25) is controlled by the frequency controller to produce the reference signal. Receiving a radio signal by double superheterodyne, the radio receiver gives the eventual intermediate frequency to the amplified signal. In the amplified signal, the frequency controller suppresses an eventual frequency drift which results from frequency drifts of a first local oscillation and a second local oscillation. The radio receiver may be a single superheterodyne receiver.

Abstract: Pluralities of estimated desired and interference signal sequence candidates corresponding to the states of transition of desired and interference signals estimated to receive are sequentially generated in a state estimation part 40, from which they are provided to a desired signal estimation part 10 and an interference signal estimation part 20. These estimation parts 10 and 20 generate estimated desired and interference signals from the sequence candidates in accordance with conversion parameters from a channel parameter estimation part 50. A signal of their sum is subtracted in an error estimation part 30 from a received signal to yield an estimation error signal .epsilon.. The state estimation part 40 estimates estimated desired and interference signal sequences for the generated sequence candidates.

Abstract: A radio communication system operates between two radio terminals, and/or between a radio terminal and a fixed terminal through a network. In the present disclosure, the switching of codec-release mode and codec mode in the network is controlled by using a specific control line which is installed in addition to a speech line. Thus, when a radio terminal communicates with another radio terminal through a network, no codec is used in the network, and so, speech distortion and signal delay are not deteriorated due to signal conversion by using a codec.

Abstract: A frequency diversity communication system is provided whereby the number of hopping channels is reduced and a more continuous communication achieved as a mobile station travels from cell to cell by the combination of chips of symbols from the mobile sources. The transmitter divides each symbol of an input symbol sequence into a number K of chips, which are modulated with mutually different carrier frequencies. The receiver demodulates the signal sent by the transmitter by local frequencies corresponding respectively to the K different carrier frequencies. According to this invention, the carrier phase is coherent for each frequency of the received wave. Moreover, because the carrier phase is coherent, the outputs for each frequency of the received wave can be combined with the use of a training signal. The receiver also performs an estimation of the maximum likelihood of the transmitted symbol to eliminate the need for decoding.