摘要:
In CDMA mobile communication of the packet switching mode which is one-way, the packet is transmitted to divide to a frame unit. In this time, the first, the second and the third transmission timing which are obtained to divide to three pieces the predetermined frame are set up for increasing the transmission efficiency by realizing the retransmission of the frame unit, as the transmission timing of a backward control signal in a backward channel,. Base station 100 transmits a forward signal (a forward control signal and an user data signal) by using code A (a forward channel) at any frame. When the forward signal is received at this frame by mobile station 70, mobile station 70 transmits a receiving acknowledgment signal (a backward control signal) of the forward signal by using code A' at the first transmission timing of the next frame. Conversely, when the forward signal is not received correctly, mobile station 70 transmits a retransmission request signal (the backward control signal) of the forward signal by using code A' at the first transmission timing of the next frame. The similar operation carries out in mobile stations 80 and 90. However, in this case, the transmission timing of the backward channel is the second or the third timing.
摘要:
In an error control device, an error correction decoding portion 33 selects a bit position which has low reliability from the received signal by means of a predetermined bit number, generates error patterns by assuming that the errors exist at the bit position, and carries out modified Chase decoding for the received signals on the basis of each error pattern in modified Chase decoding portion 332. Modified Chase decoding portion 332 calculates the reliability of each error pattern by using the reliability of each bit in the received signal.
摘要:
A signal transmission method checks, when detecting an occurrence of a communication request, whether the communication request is a high speed communication (step S302). In the case of the high speed communication, it checks whether the number of current high speed communications (m) plus one is greater than the upper limit (mmax) of the high speed communication (step S312). If greater, it cancels the request as a call loss (S316), and sets to a variable a the ratio (h) of the rate of the high speed communication to that of a low speed communication. If the communication request is the low speed communication, it sets one to the variable a (step S304). It compares n plus a with nmax (step S306), where n is the total number of all the current communications, a is the value associated with the communication request, and nmax is the upper limit of the number of communications acceptable in a bandwidth, all of which are expressed in terms of the number of the low speed communications. If n plus a is greater than nmax, the communication request is canceled as a call loss (S316). Otherwise, the total number of the current high speed communications (m) and the total number of all the current communications (n) expressed in terms of the number of the low speed communications are updated, and a channel is assigned to the communication request (step S310).
摘要:
A biological tissue equivalent phantom unit to be used by the specific absorption rate measuring system for evaluating absorption of electromagnetic wave energy includes a biological tissue equivalent phantom for absorbing an electromagnetic wave. In addition, two or more electro-optical crystals are arranged at two or more measurement points in the biological tissue equivalent phantom. The electro-optical crystals have a dielectric constant that is approximately equal to that of the biological tissue equivalent phantom. Two or more optical fibers are laid in the biological tissue equivalent phantom for optically connecting each of the electro-optical crystals to an external destination.
摘要:
A signal transmission method and apparatus over a forward traffic channel in cellular mobile communications that can simultaneously perform one or more high speed communications whose transmission rates are higher than or equal to a predetermined rate, and one or more low speed communications whose transmission rates are lower than the predetermined rate between a plurality of mobile stations and a base station.
摘要:
A specific absorption rate measuring apparatus comprises a probe configured to measure, in a two-dimensional plane, the amplitude and the phase of an electric or magnetic field generated in a phantom of which electrical properties similar to a human body tissues; an electric and/or magnetic field estimation unit configured to estimate a three-dimensional electric field distribution to be produced from a wave source defined by the two-dimensional electric and magnetic fields at a measuring point, based on the measurement results of the probe; and a specific absorption rate estimation unit configured to estimate a three-dimensional distribution of specific absorption rate based on the estimation result of the electric field estimation unit.
摘要:
A communication channel allocation method allocates a communication channel to communications between a mobile terminal device and a second radio base station using a second frequency band which is close to a first frequency band used by a first radio base station, by detecting a first distance between the second radio base station and the first radio base station, detecting a second distance between the second radio base station and the mobile terminal device when the first distance is less than a first threshold, and allocating a communication channel of a frequency far from the first frequency band in the second frequency band to the communications between the second radio base station and the mobile terminal device when the second distance is less than a second threshold.
摘要:
A transmitted signal is enciphered or concealed to thereby prevent interference, even when data indicative of the receiver terminal is made public because of the use of a common access channel. In the transmitter, in a random-number bit adder 6, a random-number .alpha. (digital signal) generated by a random-number generator 5 is inserted into a transmitting data signal DA generated by a transmitting data generator 1, and the resultant is outputted as a signal (DA, .alpha.). An encipherment processor 2 enciphers the signal (DA, .alpha.) and outputs it as a signal (DA, .alpha.)'. In the receiver, this signal (DA, .alpha.)' is deciphered into (DA, .alpha.), and the random-bits .varies. are removed from (DA, .alpha.) to restore the signal DA.
摘要:
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.
摘要:
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. At a receiving side, the preamble is detected and the decoded results of the coded actual speech data subsequent to the detected preamble are output as a speech signal. When a predetermined number of successive coded actual speech data have been detected without having detected a preamble preceding thereto, it is decided that the decoded results of the coded actual speech data are in a speech-active duration and the decoded results are outputted as a speech signal.