Multiplex communications – Channel assignment techniques – Adaptive selection of channel assignment technique
Reexamination Certificate
1997-10-16
2001-07-10
Nguyen, Chau (Department: 2663)
Multiplex communications
Channel assignment techniques
Adaptive selection of channel assignment technique
C359S199200
Reexamination Certificate
active
06259702
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a server system for storing and reproducing information and a method for delivering information from the server and for storing information in the server. More particularly, the invention concerns the server system and the delivering and storing method for dealing with continuous signals such as video signals. The invention also relates to the server system and the delivering and storing method capable of being simultaneously used at arbitrary timing through plural terminal units.
2. Related Background Art
The following describes the technology for storing or reproducing information, as described in Japanese Laid-open Patent Application No. 3-58348 filed prior to the present application by the applicant of the present invention.
FIG. 13
is a conceptual drawing of the above prior art. Reference numeral
1301
designates a system controller for controlling this information recording and/or reproducing device. Numeral
1302
is a crossbar switch for switching connection between three input/output routes
1304
to
1306
and three optical disks
1307
to
1309
each for storing/reproducing information. Numeral
1303
indicates a management table for the system controller
1301
to refer to for control of crossbar switch
1302
and control of reading/writing with each optical disk, which stores the status of each optical disk.
A continuous signal supplied through the input/output route
1304
is given destination addresses changed in order by the crossbar switch
1302
and is recorded as distributed as partial signals in the respective optical disks
1307
to
1309
. Reproduction of the signals recorded in the optical disks is also carried out by reading the partial signals recorded in the respective optical disks. At this time the crossbar switch also switches connection in a predetermined order so as to continuously supply the partial signals outputted from the respective optical disks to one input/output route.
Another conceivable configuration is a server system for delivering signals by use of a switching system for carrying out the ordinary arbitration control. A prior art switching system of this type will be described below.
FIG. 14
shows a crossbar type switching system having N input terminals and N output terminals as a first example of switching system. In
FIG. 14
numeral
87
denotes decoders, each of which reads an address part of a packet and informs the control unit of an output terminal to which this packet should be directed. Numeral
88
represents FIFOs (First In First Out), each of which temporarily stores an input packet and outputs it in the input order to an output line according to control from the control unit. Numeral
89
indicates input lines for supplying a packet signal outputted from the FIFO to an input of switch. Numeral
90
denotes switches, each of which serves as a switch of whether or not a packet signal supplied to an input line is to be outputted to an output line. Numeral
91
represents the control unit, which performs the reading control of each FIFO and the control of opening/closing of each switch, according to the output from the decoders. Numeral
92
indicates output lines, each of which supplies a packet signal outputted from the switch, to an output terminal.
In this crossbar type switching system, the control unit performs the routing control for changing the output terminal to be selected for output, by controlling opening/closing of switches connected to a desired output terminal. The control unit also carries out the arbitration control; when the so-called output contention occurs as inputs from plural input terminals simultaneously request outputting to one output terminal, the control unit executes the arbitration control for determining which input out of these plural inputs is to be outputted. The switching operation is achieved based on these controls.
This first example of switching system, however, had a drawback that the scale of hardware became very large, because, in the case of the N input terminals and N output terminals, N×N switches were necessary.
In this first example of switching system, N outputs of switches for connection between plural input lines and output lines are connected to one output line. This results in long wiring of connection lines, which causes occurrence of wiring delay, increase of stray capacitance of wiring, and so on. Increase of the number N of input terminals would make it difficult to increase the operating speed of switch. Therefore, this first example of switching system has a drawback that it is not suitable for quick switching of input packet signal.
In addition, this first example of switching system includes a need for carrying out the arbitration control while detecting occurrence of output contention as to inputs from the all input terminals, for every output terminal. Therefore, it had a drawback that the scale of hardware of the control unit for this control increased.
FIG. 15
shows a second example of switching system for overcoming the drawbacks of the first example of switching system described above. In this example the switching system is configured of switches of 2×2 having two input terminals and two output terminals, described below, connected in multiple stages. In
FIG. 15
numeral
93
to numeral
104
represent the switches of 2×2 with two input terminals and two output terminals, which have two functions, straight connection for connecting the input terminals with the output terminals straight and cross connection for connecting the input terminals with the output terminals in a crossing manner. These twelve switches of 2×2 are connected in a shuffle network pattern, thereby realizing an omega switching system with eight input terminals and eight output terminals.
FIG. 16
is a structural diagram to show the inside of the switch of 2×2 with two inputs and two outputs described above. In
FIG. 16
numerals
105
and
106
denote decoder I and decoder II, each of which reads an address part of an input packet and informs the control unit of an output terminal to which this packet is to be outputted. Numerals
107
and
108
represent FIFO I (First In First Out) and FIFO II, each of which temporarily stores an input packet and outputs it in the input order to a selector, based on the control from the control unit. Numerals
109
and
110
indicate selector I and selector II, each of which selects an FIFO storing a packet signal to be outputted to an output destination, based on the control from the control unit. The aforementioned straight connection is a state in which the selector I selects the FIFO I while the selector II selects the FIFO II; the aforementioned cross connection is a state in which the selector I selects the FIFO II while the selector II selects the FIFO I.
In this second example of switching system, the number of switches 2×2 necessitated is NlogN−N/2 (wherein the base of log is 2), which is smaller than N×N in the first example. The second example, however, necessitates the decoders, FIFOs, control unit, and selectors for each switch of 2×2, and thus had a drawback that the scale of hardware as a whole became large. Furthermore, this second example of switching system had a problem that even in case of connection being not from different input terminals to one output terminal, the so-called blocking phenomenon that connection to a desired output destination was not achieved, occurred depending upon circumstances of connection of the other input terminals. Specifically, for example when the input terminal
5
is connected with the output terminal
3
in
FIG. 15
, the switch
93
of 2×2 is set in the crossing state, and blocking occurs in connecting the input terminal
1
with the output terminal
1
, because the switch
93
of 2×2 has to be set in the straight state.
The switching systems with the electrical switches as shown in the first and second examples of switching system had a drawba
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Lee Chiho Andrew
Nguyen Chau
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