Showing papers by "NTT DoCoMo published in 1998"

Variable rate transmission and reception methods, and variable rate transmission and reception devices

Abstract: A transmission method for implementing variable rate transmission. Part of the baseband processing of a transmitter based on a CDMA transmission scheme is described. A transmitted information sequence in the form of a digital signal is phase modulated by a phase modulator 105. An orthogonal code generator 101 selects, in response to rate information of the transmitted signal, the orthogonal code to be generated. The bit rate of the orthogonal code the orthogonal code generator 101 generates is double the maximum transmission rate. The modulated transmitted signal is multiplied by the orthogonal code corresponding to the rate information with a multiplier 103. The transmitted signal, which is multiplied by the orthogonal code corresponding to the rate information, is further multiplied by a spreading code sequence with a multiplier 104 to be spread into a CDMA signal, and is transmitted under power transmission control based on the rate information. A receiving side can detect the rate without information about the transmission rate.

Mobile radio communication system, mobile station, and method for controlling diversity hand-over branch

Abstract: A branch candidate selecting method by a mobile station and a diversity handover control method on a network side in DHO performance are provided which consider a maximum cable branch number and a maximum radio branch number of the mobile station, when the mobile station detects a plurality of addition branch candidates and deletion branch candidates. The mobile station inserts a plurality of addition branch candidates and deletion branch candidates, that is, all the DHO candidates into one handover trigger signal, and notifies the network. The addition branch candidates are put into addition information parameters in the handover trigger signal, and the deletion branch candidates are put into deletion information parameters. To simplify processing on the network side, the network side separates the addition branch candidates from the deletion branch candidates, and carries out sequential processing of them independently.

Receiver and method for coherent reception using received pilot symbols

Abstract: of EP1011211A base station including a transmitting and receiving amplifier for amplifying CDMA signals exchanged with a mobile station; a radio stage connected to the transmitting and receiving amplifier for carrying out D/A conversion of a transmitted signal that undergoes baseband spreading, followed by quadrature modulation, and for carrying out quasi-coherent detection of a received signal, followed by A/D conversion; a baseband signal processor connected with the radio stage for carrying out baseband signal processing of the transmitted signal and the received signal; a transmission interface connected with the baseband signal processor for implementing interface with external channels; and a base station controller for carrying out control such as management of radio channels and establishment and release of the radio channels. The base station communicates with the external channels using ATM cells, and with the mobile stations using the CDMA signals by mapping a plurality of logical channels into a plurality of physical channels. The CDMA signals are spreading using two types of spreading code sequences, that is, a short code and a long code.

Signal reception apparatus for DS-CDMA cellular system

Abstract: A plurality of sets of spreading code sequences are stored in registers and selectively supplied to matched filters. The soft-handover, multi-code processing and long-delay paths can be processed by a small circuit.

Packet data band control method in packet exchange network and packet exchange network system

Abstract: In an ATM transmission line, the band in an individual VP whose band is ensured is multiplexed for a plurality of users with a certain traffic or more to use the band efficiently. Further, a shared VP whose band is not ensured is made to exist for a low traffic user and the changeover from a shared VP to an individual VP or from an individual VP to a shared VP can be carried out under the following conditions: (1) While communication is performed through an individual VP, the user traffic is monitored at regular time intervals. When the traffic becomes lower than a certain threshold, the individual VP is changed to a shared VP. (2) While communication is performed through a shared VP, the user traffic is monitored at regular time intervals. When the traffic exceeds a certain threshold, the shared VP is changed to an individual VP. (3) In addition to the condition (2), if a shortage occurs in the band in a shared VP, the VP of the high traffic user is changed from the common VP to an individual VP.

Method of handover control in mobile radio communication realizing reduced control load

Abstract: In the method of handover control, when a mobile station recognizes that the mobile station has moved to an overlapping area, the mobile station notifies this fact to a network side and in response the network side sets up only a communication channel between a handover target base station and an exchange station for controlling that handover target base station, without setting up a radio channel between the handover target base station and the mobile station, while continuing the communication by not releasing the communication channel between the currently located base station and the exchange station and the radio channel between the currently located base station and the mobile station, so that it becomes possible to reduce a transmission control load for transmission between the base station and the exchange station as well as a control load for controlling the exchange station itself.

Signal transmission method and base station in mobile communication

Abstract: 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.

Signal reception apparatus for DS-CDMA communication system

Abstract: A signal reception apparatus for DS-CDMA communication system having a complex matched filter for despreading a received signal into I- and Q-components Di and Dq of despread signal. Dj and Dq are input to a path selection portion 13 for extracting a phase error in a pilot symbol block of the despread signal. A phase compensation signal is calculated according to the phase error in the portion 13. An information symbol is compensated according to the phase compensation signal. An electrical power is calculated from an average of the phase compensation signal of several slots for selecting paths to be received. The selected paths are combined with phase synchronized by a rake combiner 14.

Reception apparatus for CDMA communication system

Abstract: A signal reception apparatus for DS-CDMA communication system has a matched filter for despreading the received signal into the quadrature components Di and Dq. A phase compensation and path selection portion (13) extracts and averages, the phase error of the selected paths. The selection of the paths is made by the path selection portion (23) using the electrical power of the phase compensation signal. The selected paths are combined in a RAKE combiner (14).

Signal transmission method and base station device for mobile communications

Abstract: When a request for communication is detected, a check is made to see whether the communication requested is a high-speed communication (S302). If it is a high-speed communication, check is made to see whether the number (m) of high-speed communications currently effective plus one is larger than the upper limit (mmax) of the high-speed communications (S312). If it is found to be larger than the limit, the request is handled as a call loss (S316). If it is found to be smaller, a variable (a) is preset as a speed ratio (h) between the high-speed communication and the low-speed communication (S314). When the communication requested is a low-speed communication, the variable (a) is preset as one (S304). The number of communications requested as calculated in terms of low-speed communication requested (a) is added to the total number of current communications in terms of the low-speed communications (n), and the combined value is compared with the upper limit (nmax) of the communications that can be accommodated in a bandwidth in terms of low-speed communication (S306). When the combined value is larger than the upper limit (nmax), the request is a call loss (S316). Otherwise, the number of current high-speed communications (m) and the total number of current communications calculated in terms of low-speed communication are updated and a channel is allocated to the communication request (S310).

Packet communication network

Abstract: A packet communication network in a fixed network used for a mobile communication network is controlled as follows. (1) A user to/from whom a certain traffic or more of packets are not transmitted for a certain time is put into a communication hold mold. The communication hold mode is a mode in which 'a resource in the network is temporally released but a gate station between the mobile station and another network behaves as if a communication set state continues on the user side and the other network side'. (2) If the user in a communication hold state resumes packet transmission, the mobile station performs a re-calling without operation of the user and resets a communication set state for communication with the gate station. (3) If the gate station resumes the reception of the packet for the user in a communication hold state, the gate station performs the re-reception without control in relation to another network and resets a communication set state for communication with the mobile station. (4) In order to realize the re-reception of (3), the mobile station performs position registration if the mobile station moves from one position registration area to another after the transition to a communication hold state.

Method of handover control in mobile radio communication system

Abstract: In the method of handover control according to the present invention, when the mobile station recognizes that it has moved to an overlapping area, the mobile station notifies this fact to the network side and in response the network side sets up only a communication channel between the handover target base station and the exchange station for controlling that handover target base station, without setting up a radio channel between the handover target base station and the mobile station, while continuing the communication by not releasing the communication channel between the currently located base station and the exchange station and the radio channel between the currently located base station and the mobile station, so that it becomes possible to reduce a transmission control load for transmission between the base station and the exchange station as well as a control load for controlling the exchange station itself.

Telecommunication apparatus and method

Abstract: The apparatus has a Transmission/reception amplifying unit (2) for the amplification of CDMA signals from and to a mobile station. A base band-spread transmission signal which is passed through the amplifying unit is then D-A converted to analogue by a radio unit (3) and then quadrature modulated, quasi-synchronously detecting a received signal which is then A-D converted to a digital signal. The system also has a base band signal processing unit (4), connected to the radio unit which subjects both the transmission and received signals to the base band signal processing, a transmission channel interface (6) which is connected to the base band signal processing unit which serves as an interface with an external line, and a control unit which controls radio circuits and their setting/resetting. Communication with an external line occurs using ATM cells. The communication with the mobile station by using CDMA signals is effected by mapping a series of logic channels on a series of physical channels. The band of the CDMA signals is spread with two short and long spread-series codes.

Code generation for a mobile communication system

Abstract: A base station including a transmitting and receiving amplifier for amplifying CDMA signals exchanged with a mobile station; a radio stage connected to the transmitting and receiving amplifier for carrying out D/A conversion of a transmitted signal that undergoes baseband spreading, followed by quadrature modulation, and for carrying out quasi-coherent detection of a received signal, followed by A/D conversion; a baseband signal processor connected with the radio stage for carrying out baseband signal processing of the transmitted signal and the received signal; a transmission interface connected with the baseband signal processor for implementing interface with external channels; and a base station controller for carrying out control such as management of radio channels and establishment and release of the radio channels. The base station communicates with the external channels using ATM cells, and with the mobile stations using the CDMA signals by mapping a plurality of logical channels into a plurality of physical channels. The CDMA signals are spreading using two types of spreading code sequences, that is, a short code and a long code.

Multiplex transmission system and band control method

Abstract: A multiplexer which multiplexes packets with an ATM cell before transmission and realizes efficient use of a transmission line accommodating irregular traffic characteristics of service having various quality conditions in an actual environment. When a connection setup is requested (S402), currently required bands B1, ..., Bm are modified into B'1, ..., B'm by adding a new connection and the bands X1, ..., Xm assigned to the transmission line are intended to be modified. If a required band allowing for the requested connection is narrower than a band available on the transmission line, a procedure for modifying an assigned band is actuated (S406) and the band thus modified is assigned according to the band required after modification. Assignment of band is modified by varying the rate for taking out a buffer for storing the packet in the multiplexer.

Advanced mobile multimedia services and applied network techniques

Abstract: This paper first describes the advanced mobile multimedia services required in the third-generation system. Next, we present essential network techniques for the mobile multimedia services.

Base station apparatus and method for mobile communication system

Abstract: A base station including a transmitting and receiving amplifier for amplifying CDMA signals exchanged with a mobile station; a radio stage connected to the transmitting and receiving amplifier for carrying out D/A conversion of a transmitted signal that undergoes baseband spreading, followed by quadrature modulation, and for carrying out quasi-coherent detection of a received signal, followed by A/D conversion; a baseband signal processor connected with the radio stage for carrying out baseband signal processing of the transmitted signal and the received signal; a transmission interface connected with the baseband signal processor for implementing interface with external channels; and a base station controller for carrying out control such as management of radio channels and establishment and release of the radio channels. The base station communicates with the external channels using ATM cells, and with the mobile stations using the CDMA signals by mapping a plurality of logical channels into a plurality of physical channels. The CDMA signals are spreading using two types of spreading code sequences, that is, a short code and a long code.

Mobile radio communication system, mobile station, and method for controllling diversity hand-over branch

Abstract: A branch candidate selecting method bya mobile station and a diversity handover control method on a network side in DHO performance are provided which consider a maximum cable branch number and a maximum radio branch number of the mobile station, when the mobile station detects a plurality of addition branch candidates and deletion branch candidates. The mobile station inserts a plurality of addition branch candidates and deletion branch candidates, that is, all the DHO candidates into one handover trigger signal, and notifies the network. The addition branch candidates are put into addition information parameters in the handover trigger signal, and the deletion branch candidates are put into deletion information parameters. To simplify processing on the network side, the network side separates the addition branch candidates from the deletion branch candidates, and carries out sequential processing of them independently.