Ntt Docomo, Inc.

Ntt Mobile Communications Network, Inc.

Hiroki Morikawa

Motoshi Tamura

Hiroshi Kawakami

Masatomo Nakano

Takehiro Nakamura

Seizo Onoe

Junichiro Hagiwara

Akihiro Higashi

Etsuhiro Nakano

Koji Ohno

Fumiaki Ishino

Tomoyuki Ohtani

Takaaki Satoh

Akihisa Nakajima

Yukichi Saito

Shin Nakamura

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 by mapping logical channels into physical channels. The CDMA signals are spread using a short code and a long code.

Base station apparatus of mobile communication system

Disclosed is a mobile communication system including a network constituted of at least one switching center and a plurality of base stations, and a mobile station which communicates with the base stations simultaneously. The system permits varying transmission delay between the switching center and the base stations according to the type of services available to the mobile station. The object of the present invention is to propose a communication which permits varying transmission delay according to the type of service currently employed, and to promptly recover a synchronization state even if an out-of-sync state happens. To attain the object, a memory means (mobile switching center processor) stores transmission delay characteristics corresponding to services which are available to the mobile station. Furthermore, a communication timing setting means (diversity handover trunk) determines the timing of communication for the base stations according to the transmission delay characteristic selected according to the service.

Frame synchronization circuit

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.

The invention reduces an overhead operation required for re-establishment of a physical signal link. A physical signal link (layer link) is switched over keeping a layer link in the OSI reference model. A database stores information indicating physical signal links and information indicating the maximum length of a layer frame determined according to the ability of physical signal links. When a physical signal link is to be switched over, a target physical signal link is selected and a physical signal link used by the link is switched to the target physical link without releasing the single layer link. The maximum length corresponding to the target physical signal link is obtained from the database , and layer frames having the maximum length are transmitted. Switching over a physical signal link is performed in the following manner. When a physical signal link switching-over request is given, establishment of a target physical signal link is required without releasing a layer link, and a multi-reception of control signals using both of the target physical signal link and an original physical signal link is started. After confirming establishment of the target physical signal link, a physical signal link used for transmitting a control signal is switched to the target physical signal link and release of the original physical signal link is required. After confirming release of the original physical signal link, a physical signal link for receiving a control signal is switched to the target physical signal link.

Control signal processor and communication system

A multiplex system for multiplexing packets into ATM cells to be transmitted, which can implement effective use of channels corresponding to irregular traffic qualities in services with various types of quality conditions in an actual environment. In response to a connection establishment request (S ), current required bandwidths B , . . . , Bm are changed to B , . . . , B&prime;m by adding the new connection, which causes bandwidths X , . . . , Xm which are assigned to the channels to be changed. When the desired bandwidth including the requested connection is less than an available bandwidth of the corresponding channel, an assigned bandwidth change processing (S ) is activated to assign new bandwidths in accordance with desired bandwidths. The bandwidth assignment change is carried out by changing ratios of extraction rates of packets from the buffers in the multiplex system.

Multiplex transmission system and bandwidth control method

Micro-frame multiplex transmitter

Growing community of inventors

Kanagawa, Japan

Hiroki Morikawa