AU596790B2

AU596790B2 – Channel assignment system for loop network
– Google Patents

AU596790B2 – Channel assignment system for loop network
– Google Patents
Channel assignment system for loop network

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Publication number
AU596790B2

AU596790B2
AU50065/85A
AU5006585A
AU596790B2
AU 596790 B2
AU596790 B2
AU 596790B2
AU 50065/85 A
AU50065/85 A
AU 50065/85A
AU 5006585 A
AU5006585 A
AU 5006585A
AU 596790 B2
AU596790 B2
AU 596790B2
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Australia
Prior art keywords
node
channel
nodes
channels
information
Prior art date
1984-11-20
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AU50065/85A
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AU5006585A
(en

Inventor
Kazutoshi Maeno
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NEC Corp

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NEC Corp
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1984-11-20
Filing date
1985-11-19
Publication date
1990-05-17

1984-11-20
Priority claimed from JP24532684A
external-priority
patent/JPS61123338A/en

1984-11-20
Priority claimed from JP24532784A
external-priority
patent/JPS61123339A/en

1985-11-19
Application filed by NEC Corp
filed
Critical
NEC Corp

1986-05-29
Publication of AU5006585A
publication
Critical
patent/AU5006585A/en

1990-05-17
Application granted
granted
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1990-05-17
Publication of AU596790B2
publication
Critical
patent/AU596790B2/en

2005-11-19
Anticipated expiration
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Ceased
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Classifications

H—ELECTRICITY

H04—ELECTRIC COMMUNICATION TECHNIQUE

H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION

H04L12/00—Data switching networks

H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]

H04L12/42—Loop networks

H04L12/423—Loop networks with centralised control, e.g. polling

Description

596790 SPRUSON FERGUSON FORM 10 COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 COMPLETE SPECIFICATION
(ORIGINAL)
FOR OFFICE USE: E009c5, I Class Int. Class t o t 0t 0 Complete Specification Lodged: Accepted: Published: Priority: Related Art: This-dcu ment COlainls ihe
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amndnients nude undi..
Se’ tion 49 and is correct 1′, 0 o o 0 0 0 0 Name of Applicant: Address of Applicant: Actual Inventor: Address for Service: NEC Corporation 33-1, Shiba 5-chome, Minato-ku, Tokyo, Japan KAZUTOSHI MAENO Spruson Ferguson, Patent Attorneys, Level 33 St Martins Tower, 31 Market Street, Sydney, New South Wales, 2000, Australia Complete Specification for the invention entitled: “CHANNEL ASSIGNMENT SYSTEM FOR LOOP NETWORK” The following statement is a full description of this invention, including the best method of performing it known to us SBR/as/061M 1-
ABSTRACT
A channel assignment system for allowing a plurality of nodes in a loop network, which includes a network control node, to hold a duplex communication by time division circuit switching. The network control node is provided with a channel rearrange device. Channels the number of which is smaller than that of the nodes by one are used and, in order that the nodes may be accessed as if they had individual exclusive channels, the channels are logically shifted for rearragement by the channel rearrange device after each round through the loop. Further, each of the nodes on the loop is provided with a channel rearrange device. Channels the number of which is smaller than that of the nodes are used and, in order that the nodes may be o accessed as if they had individual exclusive channels, the channels are logically shifted for rearrangement by the channel rearrange device of each node at each time of data transmission and reception.
oi o oo o 7 1 -1A- CHANNEL ASSIGNMENT SYSTEM FOR LOOP NETWORK BACKGROUND OF THE INVENTION The present invention relates to a channel assignment system for a loop network, particularly a loop network having a network control node, which allows a plurality of nodes to hold a duplex communication therebetween by time division circuit o switching.
S: A channel assignment system applicable to duplex communication which is effected between a plurality of nodes in a loop network by time division circuit switching is described in, for example, “DATA AND COMPUTER COMMUNICATIONS” written by William Stallings (published by Macmillan) pp. 307-311 and °°°339-342. An example of such a system is shown in Figs. 1-3.
Referring to Fig. 1, a prior art channel assignment system is shown which comprises a network control node, or center 15 node, 100 and nodes 102-110. The network control node 100 0 03 0. and the nodes 102-110 are interconnected by a transmission path 111 to complete a loop netwok. The control node 100 includes a demand assign device 101 adapted to assign idle channels responsive to a communication request which may be 20 sent thereto from any of the nodes 102-110. A frame with an exemplary channel arrangement is shown in Fig. 2. As shown, SI the frame includes an overhead 200 consisting of several bits and used for loop synchronization and frame synchronization purposes. The frame also includes channels 201-207.
Generally, concerning circuit switching in a loop type network, a plurality of channels are set up in bits or bytes on a time division basis along a tirme base 208. In the illustrated example, -2the frame comprises the seven channels 201-207 and the overhead 200.
In Fig. 1, let the nodes 103, 104, 107 and 110 be called nodes A, B, C and D, respectively, and assume that all these nodes A-D are capable of performing multi-station duplex communication. Then, as shown in Fig. 3, four idle channels are secured and assigned one to each of the nodes A-D. In this particular example, a channel 1 designated by the reference numeral 301 is assigned to the node A, a channel 2 designated by the reference numeral 302 to the node B, a channel designated by the reference numeral 305 to the node C, and a channel 6 designated by the reference numeral 306 to the node D. Each of the nodes A-D reads pieces of information from the other three nodes through an exclusive read channel, while sending information to the other nodes on an exclusive write channel of its own.
The prior art channel assignment system as described above has the following problem. For N nodes on the loop network to hold a duplex communication therebetween, it is necessary to o’o 20 secure N idle channels. However, considering the topology particular to a loop, information is sequentially routed through the nodes according to a predetermined transmission direction of the loop, so that information transmitted from a certain node is practically valueless while it is returned from the last node in the loop, as viewed from the transmitted node, to the transmitted node. For example, in the case of digital picture transmission which needs a data rate of the order of 100 Mbps, meaningless information is undesirably propagated through the loop at the o rate of 100 Mbps between the last node and the transmitted 30 node. Such significantly limits the available transmission capacity of a loop network.
SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a channel assignment system for a loop network which minimizes
ZE~FI
the number of channels necessary for multi-station duplex communication between a plurality of nodes, which is effected on a time division circuit switching basis.
It is another object of the present invention to provide a generally improved channel assignment system for a loop network.
In accordance with one aspect of the present invention, there is provided a communication network comprising: a plurality of nodes connected in series with one another in a single loop communication system in which information from a node is transmitted to other nodes using a time division channel switching method, and a network control node connected in said single loop, said network control node including means for rearranging channel assignment by t o cyclically shifting the channels after every round through said single S loop, said channel assignment rearranging means operative for rearranging 00e0 channel assignments on a number, n, of channels smaller in number than a number N, of nodes communicating with each other such that n N 1, where n and N are integers and N is greater than 2, .00 wherein N 1 channels are assigned upon establishment of communication between N nodes, where information from each node is simultaneously transmitted to the remaining N 1 nodes by using said N 1 channels on said loop system.
00*4 S In accordance with another aspect of the present invention, there is 0 0 o 0 provided a communication network comprising: a plurality of nodes distributed in a single loop communication o system in which information from a node is transmitted to other nodes using a time division channel switching method, each of said nodes including channel rearranging means for controlling channel assignments, and each of said channel rearranging means operative for rearranging 0 channel assignments on a number, n, of channels smaller in number than a number, N, of nodes communicating with each other such than n N 1, where n and N are integers and N is greater than 2, wherein N 1 channels are assigned upon establishment of communication between N nodes, where information from each node is simultaneously transmitted to the remaining N 1 nodes by using said N 1 channels on said loop system.
The above and other objects, features and advantages of the -3nas/246y -4present invention will become more apparent from the following detailed description taken with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic diagram representative of a prior art channel assignment system for a loop network; Fig. 2 shows channels arranged in accordance with the prior art system of Fig. 1; Fig. 3 shows exemplary channels assigned in accordance with the system of Fig. 1; Fig. 4 is a schematic diagram representative of a channel assignment system embodying the present invention; Figs. 5A-5F show examples of channels which are assigned Sin accordance with the system of Fig. 4; Fig. 6 is a block diagram showing a specific construction of a network control node which is included in the system of Fig.
4;
BIB!
Fig. 7 shows in a sequence diagram a call set-up and a call cancel procedures in accordance with the system of Fig. 4; Fig. 8 is a block diagram showing a specific construction of each of the nodes which are included in the system of Fig. 4; Fig. 9 is a diagram showing a specific construction of a transmission gate which is shown in Fig. 8; Fig. 10 is a flowchart representative of a specific algorithm of a call set-up request processing in accordance with the system of Fig. 4; Figs. 11 and 12 show flows of signals between the network control node and the nodes which are associated with the algorithm of Fig. So 30 Fig. 13 is a schematic diagram showing another embodiment of the present invention; and Figs. 14A-!4E show examples of channels assigned in accordance with the system of Fig. 13.
DESCRIPTION OF THE PREFERRED EMBODIMENTS While the channel assignment system for a loop network of the present invention is susceptible of numerous physical embodiments, depending upon the environment and requirements of use, substantial numbers of the herein shown and described embodiments have been made, tested and used, and all have performed in an eminently satisfactory manner.
Referring to Fig. 4 of the drawings, a channel assignment system in accordance with the present invention is shown and comprises a network control node 400 and nodes 402-410. The network control node 400 is provided with a channel rearrange device 401. The network control node 400 and the nodes 402-410 are interconnected by a transmission path 411 to complete a loop network. The number of channels is smaller by one than the number of nodes which are in use for duplex communication. The network control node 400 restores the 00 channel arrangement in which the channels have changed place with each other after each round through the loop to original and, then, sends the restored channel arrangement to the loop.
In Fig. 4, let the nodes 403, 404, 407 and 410 be called nodes A, B, C and D, respectively. The channel assignment system will be described in relation to multi-station duplex communication which is effected between the four nodes A-.D by time division circuit switching.
A 25 Assume that information is transmitted counterclockwise through the loop as viewed in Fig. 4, and that all the iour nodes A-D are to hold a duplex communication therebetween. Before the communication, the network control node 400 secures three idle channels and informs each of the nodes A-D of which channel the node may use and to which channels the other three informations to be received by the node have been assigned, based on the positional relationship between the nodes A-D. A specific example of such channel assignment is shown in Figs.
In Fig. 5A, there are shown an overhead 500, a channel 1 designated by the reference numeral 501, a channel 2
I
-6designated by the reference numeral 502, a channel 3 designated by the reference numeral 503, a channel 4 designated by the reference numerals 504, a channel 5 designated by the reference numeral 505, a channel 6 designated by the reference numeral 506, and a channel 7 designated by the reference numeral 507.
Responsive to a request from the group of the nodes A, B, C and D, the network control node 400 secures three idle channels which, in this particular example, are assumed to be the channels 2, 5 and 6. The network control node 400 informs the node A of the fact that the channels 2, 5 and 6 store pieces of information which are transmitted from the other nodes B, C and D, respectively, and the fact that after reading those information the node A may write its own information in the channel 2. Likewise, the network control node 400 informs the 15 node B of the fact that the channels 2, 5 and 6 store pieces of information which are transmitted from the nodes A, C and D, S. respectively, and the fact that after reading those information the node B may write its own information in the channel Further, the network control node 400 informs the node C of the S0 20 fact that the channels 2, 5 and 6 store pieces information which are transmitted from the nodes A, B and D, respectively, and the fact that after reading those information the node C may write its own information in the channel 6; and the node D of the o o fact that the channels 2, 5 and 6 store pieces of information from the nodes A, B and C, and the fact that after reading those information the node D may write its own information in the channel 2.
nAfter each duplex communication link has been set up by the above procedure, the system enters into an actual communication mode. After the start of a communication, the ooo<, channels are used at each node as shown in Figs. 5B-5E. In Figs. 5B-5E, write lines into the respective nodes A-D are designated by the reference numerals 508, 510, 512 and 514, and write lines from the same by the reference numerals 509, 511, 513 and 515. -7- It will be seen from the foregoing description taken with Figs. 5B-5E that the node A deletes the information from the node B by writing its own information into the channel 2 and, likewise, the other nodes B, C and D deletes respectively the information from the nodes C, D and A by writing their own informations. This is practicable due to the topology of a loop. Specifically, concerning the node A, since the information from the node B has been read by the nodes C and D before reaching the node A, that is, since the node A is the last node to read the information from the node B, the node A is allowed to write its own information in the channel 2 after reading the information from the node B. The same holds true with the other nodes B, C and D. The channel rearrange device 401 which is installed in the S 15 network control node 400 functions to rearrange the channels before the informations are fed again to the node A after making one round through the nodes A, B, C and D. The channel oo rearrangement is shown in Fig. 5F. After propagation through o the node D, the channel 2 has stored the information associated 20 with the channel D, the channel 5 the information associated with o o of o the channel B, and the channel 6 the information associated with the channel C, as previously stated. As indicated by the reference numerals 516-518 in Fig. 5F, the channel rearrangement is such that the node D information is shifted from the channel 6 to the channel 5, the node C information from the channel 6 to the channel 5, and the node B information from the channel 5 to the channel 2. Where the channels are of the bit multiplex type, the rearrangement described above can be accomplished simply by 0 30 logically shifting the channels 2, 5 and 6 one bit round. Such an operation does not depend upon the number of communication oooo, nodes. The channel rearrange device 401 may readily be implemented using a random access memory. If the channel rearrange device 401 is absent, the order of the channels sent will have been changed at the second round through the nodes A, 1~ -8- B, C and D. Specifically, as shown in Fig. 5E, the channel 2 coming out from the node D stores the node D information, the channel 5 the node B information, and the channel 6 the node C information; should such channels be transmitted to the node A, the information stored therein would be alien to the recognition at the node A, disenabling a communication to be held. The prerequisite with each node in time division circuit switching is that the write channel and the read channel be fixed, as the network control node 400 informs each node before the start of a communication as described above. In accordance with the present invention, the channel rearrange device 401 built in the network control node 400 makes it possible to fix the channels at each of the nodes, even though the number of channels available for communications is smaller than that of 15 communication nodes by one. 4,r sp 044( 4 0 1 0C C 0r 4Q 41 0 01 D00044 CO 0 7 7 4/ 4, /4 -9- Specific constructions and operations of the network control node 400, channel rearrange device 401 and nodes 402-410 will be described with reference to Figs. 6-12. Referring to Fig. 6, a specific construction of the network control node 400 is shown. The node 400 comprises the channel rearrange device 401, indicated by a phantom block, and a control unit 412 for controlling the device 401. Functions assigned to the control unit 412 are processing various commands from the nodes 402-410 such as a call set-up and a call cancel requests, assigning channels and informing the nodes of the assigned channels, controlling channel rearrangement, and others. The channel rearrange device 401, on the other hand, comprises a demultiplexer (DEMUX) 602, an n X n (n being the number of channels) matrix switch 604, and a o 15 multiplexer (MUX) 606. Data coming in from a transmission path 608 are applied to the DEMUX 602 so that the respective channels are developed in parallel. The outputs of the DEMUX 602 are routed through the matrix switch 604 to the MUX 606 to be converted to a serial sequence, which is then fed out to a transmission line 610. ;The network control node 400 having the above construction controls channel rearrangement as will be described. As previously stated in relation to the illustrative embodiment, the rearrangement is such that the node D information is shifted 25 from the channel 2 to the channel 6, the node C information o o O S'o from the channel 6 to the channel 5, and the node B information from the channel 5 to the channel 2. This is readily accomplished with the n x n matrix switch 604 which switches the channels 2, 5 and 6 to the channels 6, 5 and 2, 30 respectively. CO o Referring to Fig. 7, an example of a call set-up procedure and that of a call cancel procedure are shown. In these particular examples, the node A out of all the nodes in the embodiment of Figs. 4 and 5 is assumed to be a calling station by way of example. In Fig. 7, STEPS and (7) o 0 0 0 0 0 o t o 0iD o Ro 0 0 a a o ~o 0 0r 0000 O 0E 0 00 0 0~oa a o represent notification of link set-up information, STEPS and acknowledgement (ACK) responsive to the link set-up information, STEPS and notification of link cancel information, and STEPS and acknowledgement (ACK) responsive to the link cancel information. Referring to Fig. 8, a specific construction of each of the nodes 402-410 is shown. As shown, the node comprises a DEMUX 702, reception channel selectors 704, 706 and 708, a transmission gate 710, a MUX 712, a control unit 714, and a transmit/receive terminal 716. The node shown in Fig. 8 is applicable to four-station duplex communication as shown in Figs. 4 and 5 and, for this reason, furnished with three reception channel selectors. The control unit 714 fulfills the 15 functions of delivering commands from the transmit/receive terminal 76 to the network control node 400, and controlling the selection of channels for transmission and reception. The control unit 714 comprises a microprocessor and the abovestated functions are implemented with software. 20 The node having the above construction will be operated as follows. Data from a transmission path 718 are applied to the DEMUX 702 to be developed in parallel channel by channel. The data output from the DEMUX 702 are fed to the reception channel 25 selectors 704, 706 and 708 for selecting a reception channel and to the transmission gate 710 for selecting a transmission channel. The selection is controlled by the control unit 714 responsive to selection data which are supplied from the network control node 400. A specific construction of the transmission gate 710 is shown in Fig. 9. In the duplex communication between the nodes A-D of the illustrative embodiment, the node A, for example, selects the channels 2, 5 ind 6 by means of the reception channel selectors 704, 706 and 708 so as to read information from the nodes B, C and D, respectively. The transmission gate 710 selects the channel 2 to write the own -11information therein. Referring to Fig. 10, there is shown an exemplary algorithm for implementing a call set-up request processing which the network control node 400 performs in the channel assignment system of the present invention. Flows of signals between the network control node 400 and the nodes A-D which are associated with the algorithm of Fig. 10 are shown in Figs. 11 and 12. The flow shown in Fig. 11 represents a path which goes through STEPS 1, 2, 3, 4, 5, 6, 7 and 8 of Fig. 10, while the flow shown in Fig. 12 represents a path which goes through STEPS 1, 2, 3, 4, 10, 11, 12 and 8. STEPS shown in Fig. 11 and STEPS (19) shown in Fig. 12 represent call cancel request processings which are common to each other. A call cancel request is assumed to be generated by a particular node which has generated a call set-up request without exception. The duplex commur.ication between the nodes A-D of the illustrative embodiment will be described with reference to Figs. A l" 1 10 and 11. oaf" 20 A call set-up request processing will be described first, 0 0 referring to Fig. 11. a) The network control node 400 receives a call set-up request from the node A which desires to communicate with the nodes B, C and D, STEP b) The control node 400 secures thee idle channels (channels o 0 2, 5 and 6 in the illustrative embodiment) and, then, returns a channel secure signal to the node A. When no idle channel is "found, the control node 400 returns a reject signal to the node A aoind finishes the processing, STEP S 30 c) The control node 400 sends a call set-up request 0° notification to the node B to inform it of the request from the node A, STEP d) The node B responds to the notification by notifying the control node 400 whether it is idle or busy (it is assumed to be idle for the following steps), STEP i -12e) The STEPS and are repeated on each of the other nodes C and D, STEPS and and STEPS and f) At the STEP the control node 400 has confirmed that all the nodes B, C and D are idle, STEP 5 of Fig. g) Before advancing to STEPS the control node 400 performs STEP 6 as shown in Fig. 10. Specifically, the network control in the channel assignment system of the present invention is characterized in that orders of connection of all the nodes which are covered by the loop network are stored in a table. For example, in the loop network of Fig. 4, the nine nodes 402-410 are interconnected in a loop. Such data are stored as shown in Table 1 below by way of example. Table 1 'I E I o o 0 0 0 a II 1*t 0 00 0 0 0d ou~e 0 'O 20 UPSTREAM DOWNSTREAM NODE NO. NODE NODE 402 410 |3 4031 402 404 404 403| 405 405 404 406 406 405 407 407 406 408 408 407 409 409 408 410 410 409 402 Here, numbers 403, 404, 407 and 407 are assigned to the nodes 30 A, B, C and D, respectively. In which order the nodes A, B, C and D are interconnected is determined using Table 1. Let such a connection be called a logical loop. Tracing Table 1, the control node 400 prepares Table II as shown below. r -13- Table II NODE UP S TPEAM DOWNSTREAM NODE NODE A D B B A C C B D D C A Based on Table II, the control node 400 sets up a link as described in relation to the illustrative embodiment, STEP 6 of Fig. 10; and h) The control node 400 supplies each of the nodes A-D with link set-up data, STEPS (12). This is the end of the call set-up processing. Next, a call cancel processing will be described with reference to Fig. 11. i) The node A which has generated the call set-up request sends a call cancel request to the control node 400, STEP (13) 20 j) Responsive to the request, the control node 400 returns o o an answer to the node A, STEP (14) k) The control node 400 sends a call cancel request notification to the node B. Then, the node B cancels its own o channel selection control, STEP (15) 1) After the above processing, the node B returns an answer S- to the control node 400, STEP (16); m) The STEPS (15) and (16) are repeated on each of the nodes C and D, STEPS (17) and (18) and STEPS (19) and and n) Responsive to an answer from the node D, the control S node 400 cancels the logical loop table associated with the nodes O. A-D. This is the end of the call cancel processing. Referring to Fig. 12, a control flow which will occur when the answer at the STEP shows that the node B is busy is -14shown. In this case, communication is held betveen the nodes A, C and D. Details of this particular control flow will not be described. It is to be noted that the algorithm shown and described is only illustrative, that is, even an algorithm in which the control node 400 receives a request by sending polling signals to the nodes is applicable to the present invention. Referring to Fig. 13, another embodiment of the channel assignment system in accordance with the present invention is shown. In this particular embodiment, the system comprises a center node 800 and nodes 801-807 which are interconnected by a transmission line 808. The nodes 801-807 are provided with channel rearrange devices 901-907, respectively. The number of channels available for the multi-station duplex communication 15 between a plurality of nodes, which is based on time division ,i ;circuit switching, is smaller than that of the nodes by one, as previously stated. In the illustrative embodiment, the channel rearrange devices 901-907 associated with the nodes 801-807 o°"i which are distributed in the loop network are each constructed to 20 logically shift the usable channels at each time of data transmission and reception, thereby rearranging the channels. The rearranged channels are transmitted from one node to the nwxt node so that, at the end of one round through the loop, the channel arrangemer, is restored to a one before the round. In the loop network of Fig. 13, let the nodes 801, 803, 806 and 807 be called nodes A, B, C and D, respectively. The channel assignment system will be described assuming that multi-station duplex communication is effected between the four °0 nodes A-D on a time division circuit switching basis. 4.o 30 In Fig. 13, assume that information is routed BB counterclockwise through the loop network. In the case where """all the four nodes A-D are conditioned for duplex communication, the center node 800 before the communication secures three idle channels and informs each of the nodes A-D of a particular channel available for the node and to which channels I the other three pieces of information to be received by the node have been assigned, based on the positional relationship between the nodes A-D. A specific example is shown in Figs. 14A-14E. In Fig. 14A, a channel arrangement is shown and comprises an overhead 900, a channel 1 designated by the reference numeral 901, a channel 2 designated by the reference numeral 902, a channel 3 designated by the reference numeral 903, a channel 4 designated by the reference numeral 904, a channel 5 designated by the reference numeral 905, a channel 6 designated by the reference numeral 906, and a channel 7 designated by the reference numeral 907. When the group of the nodes A-D has sent a request to the center node 800, the latter secures three idle channels which in the illustrative embodiment is assumed to be the channels 2, 15 and 6. The center node 800 notifies the node A of the fact that information from the node B is stored in the channel 2, information from the node C in the channel 5, and information ao from the node D in the channel 6. The center node 800 also informs the node k of the fact that the latter may write the own information in the channel 6 after reading the those information associated with the nodes B-D and, then, logically shifting the node C information from the channel 5 to the channel 2 and the node D information from the channel 6 to the channel o so «Likewise, the center node 800 informs the node B of the fact that the node C information is stored in the channel 2 and the node A information in the channel 6, and the fact that after reading those information the node B may write the own information in the channel 6 after logically shifting the node D information from the channel 5 to the channel 2 and the node A information from the channel 6 to the channel 0 Further, the center node 800 informs the node C of the fact o that the node D information is stored in the channel 2, the node information A in the channel 5, and the node B information in the channel 6, and the fact that after reading those information the node C may write the own information in the channel 6 after i i -16logically shifting the node A information from the channel 5 to the channel 2 and the node B information from the channel 6 to the channel 5. Finally, the center node 800 informs the node D of the fact that the node A information is stored in the channel 2, the node B information in the channel 5, and the node C information in the channel 6, and the fact that after reading those informations, the node D may write the own information in the channel 6 after logically shifting the node B information from the channel 5 to the channel 2 and the node C information from the channel 6 to the channel 0 0/ 0 0 0 l4 a i s/ 00000/ O 0I CUI Ooar/ _I I I 4 4 0*t 4, *41. 0 0 D 4 4 aQ 0 0~ 0 0w4 0 00 u 40 0400J 4 4) 0uj 00U 4 0 O OUo 60000I 4o 0 -17- The procedure for setting up each duplex communication link in accordance with the channel assignment system of the present invention is characterized in that the only information which has to be supplied to each of the participant nodes is to which channel the pieces of information from the other three nodes, which should be received by the particular node, have been assigned, the logical shifting operations and write channels being implemented with common information. Such a procedure, therefore, is suitable for distributed control. For example, iii this particular embodiment, the nodes share the common knowledge that the content of the channel 5 is shifted to the channel 2 and that of the channel 6 to the channel 5, while the own information may be written in the channel 6. In Figs. 14B-14E, a condition of use of the channels at each node after the start of a communication is shown. The reference numerals 908-911 designate respectively read lines to the nodes A-D, while the reference numerals 912-915 designate respectively write lines from the nodes A-D. Further, the reference numerals 916-923 designate logical channel shifting 20 operations which are performed at the respective nodes. It will be seen from the foregoing description taken with Figs. 14B-14E that the node A shifts the node C information from the channel 5 to the channel 2 and the node D information from the channel 6 to the channel 5 to delete the node B 25 information, and writes the own information in the channel 6 which is then idle. Likewise, the node B deletes the node C information, the node C deletes the node D information, and the node D deletes the node A information. This is possible due to the topology of a loop. Specifically, concerning the node A, the 30 node B information from the node B is read by the nodes C and D before reaching the node A, that is, the node A is the last node to read the node B information. Hence, deleting the node B information by shifting another node information to the channel 2 which has stored the node B information does not give rise to any problem. -18- Next, the channel shifting function assigned to the channel rearrange devices 901-907 of the nodes 801-807 will be described. As previously mentioned, in the example of Figs. 14A-14A, the channel shifting function shared by the nodes A-D is shifting the content of the channel 5 to the channel 3 and that of the channel 6 to the channel The channel assignment system of the illustrative embodiment effects multi-station duplex communication between a plurality of nodes using channels which are smaller in number than the nodes by one. The prerequisite with such a system is that information sent from a certain node be deleted at the last node on the transmission loop and, when returned to the own node after a round, the information associated with the other three nodes be in the same channel assignment as before the o 15 round. The channel shifting function of the channel rearrange device at each node is characterized by the fact that each node on the loop deletes the information and fixes the channels by a o, distributed control basis. Specifically, as clearly understood 0° from the example of Figs. 14A-14E, information transmitted S 20 from a certain node is necessarily written in the channel 6 and V necessarily logically shifted one channel on the three particular channels in the same direction at each time of data transmission and reception at the other three nodes. Hence, in the cyclic 0 transmission system, or loop, information sent from the own node is always deleted at the immediately preceding node and, o further, the channels after one round are necessarily in the same arrangement as before the round. In summary, it will be seen that the channel assignment system in accordance with the first embodiment of the present invention fulfills duplex communication between a plurality of participant nodes using channels which are smaller in number CO 0than those of the prior art system by one, thereby enhancing efficient utilization of the system. Furthermore, since each of the nodes is capable of transmitting and receiving information by use of fixed channels, it is needless for any of the nodes to -19perform extra controls over the channels. That is, it is only the network control node that has to perform controls. The channel assignment system in accordance with the second embodiment of the present invention also fulfills duplex communication between a plurality of participant nodes using channels which are smaller in number than those of the prior art system by one, thereby enhancing efficient utilization of the system. In addition, even if a plurality of communication links exist, that is, a plurality of node groups for multi-station duplex communication exist, the fact that the channel arrangement is effected on a distribution basis in the links eliminates concentration of loads as would occur in a system wherein a single control node is used for centralized control and allows loads to be distributed. o 15 Various modifications will become possible for those skilled in the art after receiving the teachings of the present disclosure without departing from the scope thereof. '.3 o o 6 t Claims (4) 1. A communication network comprising: a plurality of nodes connected in series with one another in a single loop communication system in which information from a node is transmitted to other nodes using a time division channel switching method, and a network control node connected in said single loop, said network control node including means for rearranging channel assignment by cyclically shifting the channels after every round through said single loop, said channel assignment rearranging means operative for rearranging channel assignments on a number, n, of channels smaller in number than a number N, of nodes communicating with each other such that n N 1, where n and N are integers and N is greater than 2, wherein N 1 channels are assigned upon establishment of communication between N nodes, where information from each node is 15 simultaneously transmitted to the remaining N 1 nodes by using said N t 4 channels on said loop system. 2. A communication network comprising: 0* a plurality of nodes distributed in a single loop communication system in which information from a node is transmitted to other nodes using a time division channel switching method, each of said nodes including channel rearranging means for controlling channel assignments, and oo. each of said channel rearranging means operative for rearranging 0,0" channel assignments on a number, n, of channels smaller in number than a number, N, of nodes communicating with each other such than n N 1, 0 4 5 where n and N are integers and N is greater than 2, wherein N 1 channels are assigned upon establishment of communication between N nodes, where information from each node is o 0 0 simultaneously transmitted to the remaining N 1 nodes by using said N 0° 0 channels on said loop system. 3. A communication network as recited in claim 2, further including center node means for selecting idle channels and controlling channel assignments after each round through said loop. 4. A communication network substantially as described with reference to Figs. 4 14 of the accompanying drawings. DATED this TWENTY THIRD day of JANUARY 1990 Nec Corporation SPatent Attorneys for the Applicant SPRUSON FERGUSON NT- 20 nas/246y AU50065/85A 1984-11-20 1985-11-19 Channel assignment system for loop network Ceased AU596790B2 (en) Applications Claiming Priority (4) Application Number Priority Date Filing Date Title JP24532684A JPS61123338A (en) 1984-11-20 1984-11-20 Channel assignment system in loop network JP59-245327 1984-11-20 JP59-245326 1984-11-20 JP24532784A JPS61123339A (en) 1984-11-20 1984-11-20 Decentralized channel assignment system in loop network Publications (2) Publication Number Publication Date AU5006585A AU5006585A (en) 1986-05-29 AU596790B2 true AU596790B2 (en) 1990-05-17 Family ID=26537182 Family Applications (1) Application Number Title Priority Date Filing Date AU50065/85A Ceased AU596790B2 (en) 1984-11-20 1985-11-19 Channel assignment system for loop network Country Status (3) Country Link US (1) US4879714A (en) AU (1) AU596790B2 (en) CA (1) CA1266137A (en) Families Citing this family (9) * Cited by examiner, † Cited by third party Publication number Priority date Publication date Assignee Title JPH0793614B2 (en) * 1988-12-01 1995-10-09 株式会社小松製作所 Series controller GB9118040D0 (en) * 1991-08-21 1991-10-09 D2B Systems Co Ltd Method of identifying a signal path and signal processing apparatus JP2848736B2 (en) * 1992-04-02 1999-01-20 三菱電機株式会社 Network system US5517498A (en) * 1993-09-20 1996-05-14 International Business Machines Corporation Spatial reuse of bandwidth on a ring network DE19503207C2 (en) * 1995-02-02 1996-09-19 Becker Gmbh Method for the joint transmission of digital source and control data between data sources and sinks connected via data lines DE19503212C1 (en) * 1995-02-02 1996-10-02 Becker Gmbh Process for the transmission of digital data US5699356A (en) * 1995-07-17 1997-12-16 Mci Communication System and method for personal communication system dynamic channel allocation US5822420A (en) * 1996-08-30 1998-10-13 Digital Technics, Inc. Signaling protocol for multilink access network-local exchange interfaces JP3664600B2 (en) * 1999-02-16 2005-06-29 富士通株式会社 Gateway device Family Cites Families (7) * Cited by examiner, † Cited by third party Publication number Priority date Publication date Assignee Title US3961139A (en) * 1975-05-14 1976-06-01 International Business Machines Corporation Time division multiplexed loop communication system with dynamic allocation of channels US4144410A (en) * 1977-10-11 1979-03-13 Cutler-Hammer, Inc. Multiplex communication system FR2432804A1 (en) * 1978-08-03 1980-02-29 Trt Telecom Radio Electr HIGH SPEED DATA SWITCH US4383315A (en) * 1981-07-20 1983-05-10 Bell Telephone Laboratories, Incorporated Idle time slot seizure and transmission facilities for loop communication system US4460994A (en) * 1981-10-05 1984-07-17 At&T Bell Laboratories Loop communication system NL8300033A (en) * 1983-01-06 1984-08-01 Philips Nv METHOD FOR TRANSMITTING DIGITAL INFORMATION ON TRANSMISSION RINGS. 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Token ring with secondary transmit opportunities 1985 1985-11-19 CA CA000495639A patent/CA1266137A/en not_active Expired - Fee Related 1985-11-19 AU AU50065/85A patent/AU596790B2/en not_active Ceased 1985-11-19 US US06/799,582 patent/US4879714A/en not_active Expired - Fee Related Also Published As Publication number Publication date CA1266137A (en) 1990-02-20 US4879714A (en) 1989-11-07 AU5006585A (en) 1986-05-29 Similar Documents Publication Publication Date Title US4763319A (en) 1988-08-09 Multi-rate synchronous virtual circuit network for voice and data communications EP0427871B1 (en) 1996-03-20 Inter-network connection system US4907220A (en) 1990-03-06 Process for the establishment of virtual connections passing through switching matrices of a multi-stage switching system US4546429A (en) 1985-10-08 Interactive communication channel AU596790B2 (en) 1990-05-17 Channel assignment system for loop network US6298049B1 (en) 2001-10-02 Method and arrangement for upstream timeslot assignment, and communication system wherein the method is used JPS61100046A (en) 1986-05-19 Loop transmission method GB2127651A (en) 1984-04-11 Tdm concentrator system JPH08279819A (en) 1996-10-22 Digital data transmission method Chou 1975 Computer communication networks: the parts make up the whole JP3789154B2 (en) 2006-06-21 Digital data transmission method GB2125254A (en) 1984-02-29 Telecommunications digital switchblock JP2561481B2 (en) 1996-12-11 Wireless packet communication system US4387278A (en) 1983-06-07 Maintenance facility for telephony system with remote port groups JP2529862B2 (en) 1996-09-04 Multi-filament ring type network JPH09289523A (en) 1997-11-04 Packet switching repeating system JPS5857939B2 (en) 1983-12-22 Digital communication method CA1107401A (en) 1981-08-18 Data storage systems JP2635579B2 (en) 1997-07-30 Information communication system KR0118874B1 (en) 1997-10-04 Trs system with multi-repeater and method therefor JPH03186036A (en) 1991-08-14 Multiple address communication system GB1581061A (en) 1980-12-10 Data storage system WO1999009685A2 (en) 1999-02-25 Wireless telecommunications system JPS6282737A (en) 1987-04-16 Multiplex controller JPS61123338A (en) 1986-06-11 Channel assignment system in loop network
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