US 6,633,541 B1Granted

Ascending transmission speed controlling method and communication system in ATM-PON system

AssigneeFujitsu Limited

InventorsToshiyuki Hijikata, Toshio Irie, Kosuke Nobuyasu, Yoshinori Matsunaga

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Abstract

The present invention aims at providing an ascending transmission speed controlling method and a communication system in an ATM-PON (asynchronous transfer mode-passive optical network), in which ascending transmission speeds on the PON are dynamically allocated corresponding to actual transmission states of communication channels of a best effort type, to thereby effectively utilize respective bands. To this end, according to the present invention, in an OLT (optical line termination) constituting the ATM-PON system, active/inactive states of communication channels are identified based on receiving states of ascending data cells transmitted from ONU's of subscriber side, respectively, and a congestion state of the ATM network is recognized by extracting B-RM (backward resource management) cells from descending data cells, respectively, transmitted from the ATM network, so that ascending transmission speeds on the PON are allocated to communication channels corresponding to service categories, based on such as the thus recognized information.

Claims15

Dependent claims

An ascending transmission speed controlling method in an ATM-PON (asynchronous transfer mode-passive optical network) system in which said PON system has an optical line termination connected to an ATM network and a plurality of optical network units each of which is connected to a subscriber terminal to thereby send/receive cell information to/from said optical line termination, and accommodates a plurality of communication channels of best effort type in which a communication speed available by a subscriber is not guaranteed when said ATM network is congested;

said method being for controlling transmission speeds of ascending cell informations to be transmitted from said plurality of optical network units to said optical line termination;
said method comprising the steps of:
monitoring, by said optical line termination, receiving states of ascending cell informations from said optical network units, respectively to identify whether said communication channels are in active states, respectively, based on a result of monitoring;
extracting, by said optical line termination, backward resource management cells included in descending cell informations, respectively, from said ATM network;
allocating, by said optical line termination, ascending transmission speeds on said PON to said communication channels, respectively, based on said identified active/inactive states of said communication channels, a congestion state of said ATM network indicated by said extracted resource management cells, and a maximum transmission speed on said PON;
generating, by said optical line termination, ascending transmission grant signals to be transmitted to said optical network units according to said allocated ascending transmission speeds, respectively;
and
transmitting, by said optical network units, the ascending cell informations from said subscriber terminals to said optical line termination according to said ascending transmission grant signals, respectively, from said optical line termination.

5 more elements

An ATM-PON (asynchronous transfer mode-passive optical network) type communication system in which said PON system has an optical line termination connected to an ATM network and a plurality of optical network units each of which is connected to a subscriber terminal to thereby send/receive cell information to/from said optical line termination, and accommodates a plurality of communication channels of best effort type in which a communication speed available by a subscriber is not guaranteed when said ATM network is congested;

wherein said optical line termination comprises:
active state identifying means for monitoring receiving states of ascending cell information from said optical network units, respectively to identifying whether said communication channels are in active states, respectively, based on a result of monitoring;
resource management cell extracting means for extracting backward resource management cells included in descending cell informations from said ATM network;
transmission speed controlling means for allocating transmission speeds on said PON to said communication channels, respectively, based on active/inactive states of said communication channels identified by said active state identifying means, on a congestion state of said ATM network indicated by said resource management cells extracted by said resource management cell extracting means, and on a maximum transmission speed on said PON;
and
transmission grant signal generating means for generating ascending transmission grant signals to be transmitted to said optical network units according to said ascending transmission speeds allocated by said transmission speed controlling means, respectively;
and
wherein each of said optical network units comprises:
ascending transmission means for transmitting the ascending cell informations from said subscriber terminals to said optical line termination according to said ascending transmission grant signals from said transmission grant signal generating means.

6 more elements

Dependencies are inferred from the claim text.