Multiplex communications – Channel assignment techniques – Polling
Reexamination Certificate
1999-10-06
2004-06-01
Hsu, Alpus H. (Department: 2665)
Multiplex communications
Channel assignment techniques
Polling
C370S217000, C370S221000, C370S225000
Reexamination Certificate
active
06744779
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a data processing system including a plurality of units connected to a bus, and is applied, for example, to a communication control data processing system for a base station system in mobile communications such as cellular phones.
2. Description of the Background Art
In recent years, with the rapid increase of mobile communication terminals such as cellular phones, the importance of a communication control data processing system for processing a large amount of information including the start and end of a call, position registration, and monitoring of radio quality, has increased.
A conventional communication control data processing system for a base station system in mobile communications is disclosed, for example, in “Wireless Base Station System for Digital Mobile Telephone/Cellular Phone System”, FUJITSU, 45.2, pp. 112-116.
FIG. 10
is a block diagram showing the structure of the conventional communication control data processing system. The communication control data processing system includes an I/O unit
16
and a control unit
17
. Each unit has a plurality of function cards according to the type of unit. The I/O unit
16
includes I/O cards
20
, while the control unit
17
includes a bus interface card
21
, a plurality of processor cards
22
, and a shared memory card
23
. As shown in
FIG. 10
, the function cards are connected to an I/O bus
6
extending over the units and to a main bus
7
in the control unit
17
. The I/O bus
6
is structured of internal wiring
6
a
in the I/O unit
16
, internal wiring
6
c
in the control unit
17
, and a cable
6
b
connecting both units.
The communication control data processing system transmits and receives communication control data through I/O lines
24
to and from other systems (not shown) such as a base station system in mobile communications, and processes the received communication control data in parallel using the processor cards
22
. The bus interface card
21
controls the transmission of communication control data between the I/O unit
16
and the control unit
17
. The shared memory card
23
stores a control table including various information on communications.
Since a high degree of reliability is required for communication control data processing systems, the I/O bus
6
and the main bus
7
have the following characteristics. First, both buses support hot-swapping. These buses and the function cards which can be hot-swapped allow hot-swapping of a function card for active maintenance during the operation of the data processing system. Second, the function cards are daisy-chained to the buses, and both ends of each bus are terminated with terminators. With these buses, waveform distortion of transmission signals due to reflection can be corrected thereby allowing reliable data transmission between the function cards. For example, in the data processing system shown in
FIG. 10
, the function cards are daisy-chained to the I/O bus
6
, and one end of the I/O bus
6
is terminated with a resistor
38
a
while the other is with a resistor
38
b
. Similarly, the function cards are daisy-chained to the main bus
7
with both ends terminated with resistors (not shown). Daisy chain connections include not only a connection between a single driver and a multi-receiver but also include a bi-directional multi-point connection. In a daisy chain, a stub length, which is an allowable length of a branch line, is predetermined according to transmission characteristics. A connection whereby the function cards are connected in one stroke to internal wiring in a unit is one form of the daisy chain connections when the stub length is 0. Further, the daisy-chained function cards do not have any priority.
However, with the recent rapid increase in the number of terminals for mobile communications, base station systems in mobile communications for the next generation are required to deal with a number of terminals to the tune of over ten times the existing ones. Furthermore, in the base station systems for the next generation, and as performance is improved, more reliable communication control data processing systems without service interruptions are required.
In the conventional communication control data processing system, each function card has its auxiliary function card. When a fault occurs in a function card, the faulty function card is isolated, and an operation continues with its auxiliary function card, which thereby reduces downtime. However, a fault which constrains bus data transmission may occur due to a fault having occurred in the function card. With such a fault which cannot be overcome by switching a faulty function card to its auxiliary card, the conventional communication control data processing system takes a long time for recovery, which thereby causes service interruption.
To solve the above problems, each type of unit has its auxiliary unit. When a fault which cannot be overcome by switching to an auxiliary function card occurs in a unit, the faulty unit is isolated, and an operation continues with its auxiliary unit. However, in the data processing system as shown in
FIG. 10
, the internal wiring
6
a
and
6
c
is used as part of the I/O bus
6
. Therefore, to isolate the faulty unit, the I/O bus has to be temporarily disconnected so as to interrupt services.
Further, a method can be devised in which a plurality of units are daisy-chained with a cable having both ends terminated with terminators through the adoption of a SCSI (Small Computer System Interface), which is a peripheral interface for small computers. In this method, however, there are at most two SCSI drives included in each unit. Moreover, the internal cable length for connecting the SCSI drives in each unit is restricted to the stub length, which is the branch line length predetermined according to the transmission characteristics. Therefore, this method cannot be applied to data processing systems having a plurality of function cards in each unit.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a data processing system in which a plurality of units are daisy-chained with both ends terminated with terminators, which allows quick hot-swapping of a faulty unit without bus reconnection.
The present invention has the following features to solve the problems described above.
A first aspect of the present invention is directed to a data processing system in a unit structure comprising:
a plurality of units having one or more function elements, an individual bus for connecting the function elements;
a common bus which daisy-chains each of the units with both ends terminated with terminators and which supports hot-swapping; and
bus relay means for relaying data between the common bus and the individual bus.
In the first aspect, the common bus and each individual bus are independent. Therefore, when a fault occurs in a unit during operation, the bus structure and data transmission other than those concerned with the bus in the faulty unit are not affected, thereby allowing quick hot-swapping of the faulty unit for active maintenance during operation without bus reconnection.
According to a second aspect, in accordance the first aspect, the individual bus daisy-chains the function elements in each of the units with both ends terminated with terminators, and further, the individual bus supports hot-swapping.
In the second aspect, the individual bus which supports hot-swapping daisy-chains the function elements with both ends terminated with terminators, thereby allowing quick hot-swapping of a faulty function element for active maintenance without the need for bus reconnection.
According to a third aspect, in accordance with the first aspect, the bus relay means includes:
first bus receivers for receiving data from the individual bus;
first bus drivers for transmitting the data received by the first bus receivers to the common bus;
second bus receivers for receiving the data from the common bus; and
second bus drivers for tr
Kumagai Tomonori
Yamada Takahiro
Yamaguchi Masashi
Yamazaki Seiya
Yonekura Takeshi
Hsu Alpus H.
Matsushita Electric - Industrial Co., Ltd.
Tran Thien D
Wenderoth , Lind & Ponack, L.L.P.
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