Stream communication system and stream transfer control method

A stream transfer node which is applicable to any of a transmission node, a relay node and a reception node of a stream transfer system which transfers an encoding stream, which is divided into data blocks, each of the data blocks being associated with data attribute information showing a data attribute corresponding to each data block, and which has periodicity in its data structure, the stream transfer node being able to be assigned as a monitoring target node, a control target node and a management node, comprising:

• stream conversion means for performing stream shaping processing in which a transfer data volume is adjusted so that a transmission rate reaches a specified transmission rate by transmitting or annulling each data block when the stream transfer node is assigned with a role as the control target node, and an encoding stream is transmitted to a node in a next stage, while decreasing stepwise a transmission permissible priority indicating a demarcation between data transmission/annulment by using a data priority determined based on the data attribute information attached to each data block and increasing stepwise the number of transmission permissible data blocks with the same priority as the transmission permissible priority in the same cycle;
• internal state notification means for notifying a load state at the stream transfer node to a node which is assigned with a role as the management node for the same stream transfer node by an internal state notification message when the same stream transfer node is assigned with a role as the monitoring target node;
• and
• feedback control means for performing feedback control to request a setting change of a transmission rate shown by a parameter while, when the stream transfer node is assigned with a role as the management node, the stream transfer node calculates the parameter showing a transmission rate at which real time transfer at a control target node is enabled based on information showing a load data notified by an internal state notification message from the internal state notification means of the monitoring target node and a transmission rate set currently at the control target node corresponding to the monitoring target node, and the stream transfer node notifies the parameter to the control target node by a parameter setting message according to the calculation result.

A stream transfer control method applied to a stream communication system which comprises a plurality of nodes including a transmission node which is a leading stage of a stream transfer system and a reception node which is a final stage, and a network to which each node is connected, wherein each of said plurality of nodes has a stream transfer device with the function of receiving and transmitting an encoding stream which is divided into data blocks, data attribute information showing a data attribute in each data block is added, a data structure has a periodicity, and at least one node is allocated as a managing node among said plurality of nodes, and said managing node manages at least one node as a control target node among said plurality of nodes and manages at least one node located in the downstream of said control target node as a monitoring target node among said plurality of nodes, comprising the steps of:

• detecting an encoding cycle by analyzing said encoding stream;
• obtaining a data priority from said data attribute information on each data block of said encoding stream;
• measuring an amount of the transmission data every said encoding cycle;
• controlling a transmission permission priority which is a first threshold used for transmission and judgment of the annulment of a data block based on results of the amount of the transmission data at a previous cycle;
• controlling the number of transmission permission blocks which is a second threshold used for transmission and judgment of the annulment of a data block based on results of the amount of the transmission data at a previous cycle;
• adjusting the amount of the transfer data by comparing the data priority of each said data block with the first threshold and the second threshold, when said encoding stream is transmitted to a next stage node, to coincide with the transmission rate for which the effective transmission rate is specified;
• measuring a load state in the node, and notifying said managing node of a measurement result as an informative message of an internal state;
• and
• recalculating a transmission rate based on the load state notified from said monitoring target node and the transmission rate currently set, and updating the transmission rate setting by notifying said control target node of the result as a parameter setting message.