Nec Corporation

Yukie Mimura

Tomoki Osawa

A transmission apparatus and method for a frequency division multiple access (FDMA) system that uses FSK (frequency shift keying) or OOK (On/Of keying) modulation. The apparatus includes a plurality of FSK (or OOK) modulators, each of which allocates a maximum frequency shift value in the FSK (or OOK) modulation for data to be transmitted for a respective one of a plurality of channels of the FDMA system. The apparatus also includes a frequency converter for converting modulated signals output from each of the FSK (or OOK) modulators to carrier wave frequencies, and for combining the frequency-converted signals by allocating a carrier wave frequency of at least one of the plurality of channels to be between two carrier wave frequencies of another of the plurality of channels. The apparatus further includes an amplifier for amplifying the power of signal output from the frequency converter.

System and method for allocating a carrier wave frequency of one channel between two carrier wave frequencies of another channel

A method is disclosed for controlling the transmitting power of a base station in a CDMA mobile communication system. The total transmitting power Ptotal of communication channels is calculated and compared with the maximum total transmitting power Pmax. A transmitting power reduction rate D stored at the time of the previous control process is used when calculating maximum total transmitting power Pmax. The proportion of insufficiency of transmitting power is calculated as power reduction rate D based on the results of comparison, and this reduction rate D is used to reduce the transmitting power of each communication channel.

Method of controlling transmitting power of a base station in a CDMA mobile communication system

A transmission power control system in code division multiple access (CDMA) system, which makes possible to control an aimed SIR, which is compared with a measured SIR for the transmission power control, in order to maintain all channels to be an optimum communication quality even when there is a difference in communication quality in each channel in a multi-code transmission, is realized. The transmission power control system comprises at least one base station and a base station control apparatus. The base station measures the signal to interference ratio (SIR) of a received signal corresponding to each of a plurality of channels established between the base station and a mobile station, and determines a bit pattern for transmission power control for each of groups specified to the plurality of channels on the basis of the aimed SIR and the measured SIR. The base station control apparatus determines the aimed SIR on the basis of data giving groups specified to the plurality of channels and the communication quality corresponding to each of the channels, and instructs the aimed SIR to the base station.

Transmission power control system and transmission power control method in code division multiple access system

An automatic frequency assignment method, which is capable of assigning optimum frequencies to radio ports even when the radio ports are adjacent with a shield therebetween, is provides. A plurality of radio ports around a radio port to be assigned with a frequency to sequentially transmit signals at an assignment candidate frequency. A radio port already using the same frequency as the candidate frequency measures the received signal power of these signals, and compares them with a threshold. If the result of comparison reveals that there is no radio port receiving received signal power exceeding the threshold, the assignment candidate frequency is assigned. If there is a radio port receiving the received signal power exceeding the threshold, the candidate frequency is excluded from assignment candidate frequencies. This locates a radio port covered by a shielding object, so that the same frequency is prevented from being assigned to adjacent radio ports.

Method of automatic frequency assignment in a mobile communication system

A total transmitting power of a base station calculated in a total transmitting power monitor is compared with a predetermined value in a comparator. When the total transmitting power is detected to exceed a first predetermined value, the transmitting power of a pilot signal transmitted by the base station is decreased by a pilot signal transmitting power controller. As a result, a forward channel can be assigned the transmitting power even when the number of mobile stations increases. Further, a priority for disconnection of the channel may be discriminated depending upon a characteristic of the mobile station, and the channel may be disconnected based on the comparing step and the discriminating priority step.

Transmitting power control method and apparatus

An input signal from an external source is correlated to a spreading code which is indicative of the difference between first and second spreading codes which are out of phase with each other thereby to produce a correlated signal. The correlated signal is compared with first and second predetermined values to detect synchronization of the input signal with either one of the first and second spreading codes. Spreading code synchronization is achieved within a shortened period of time in a spread-spectrum communication system.

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Tokyo, Japan

Yukie Mimura