Dynamic time window and cache mechanism under the heterogeneous network transmission

A dynamic time window and cache method under the heterogeneous network transmission, comprising steps of:

• adding Available Time and Asset Size attributes of the media content in the signaling part for the existing signaling at an MMX so that a client terminal gets the time when a corresponding media content is available:
• at a same time, determining a network bandwidth and the network delay of the content from the broadband to the client under a current broadband network through a corresponding method in the network by a client:
• calculating a time interval for transmitting a request for caching in advance and a size of a cache window required by a terminal through an available time of the content of a broadband source and the delay of a broadband channel by the client terminal;
• wherein existing attributes in the CI file that can be obtained by the terminal include the time at which the object normally begins to present—begin, and meanwhile the terminal can get the uplink delay—Df' downlink delay—Dt and bandwidth of the broadband network—Bandwidth under the current broadband network by sending an HRBM message or an ARQ message in the network:
• after Available Time and Asset Size attributes of available time of the broadband content are added in the signaling, a threshold—Threshold is set:
• if the downlink delay Dt is less than the Threshold, the delay is ignored and there is no need to allocate extra cache for the media content transferred by the broadband in the system:
• if Dt is more than the Threshold, the time interval in which the media content in the broadband is requested to be sent in advance is determined and a cache window is assigned to the terminal:
• if the network delay is large and Available Time provided by the content provider does not meet the condition that the advanced caching is kept in synchronization, the content transferred via the broadband network channel is discarded directly;
• wherein the time interval in which the media content in the broadband is requested to be sent in advance is determined and a cache window is assigned to the terminal, and the specific solution is as follows:
• 1) adding AvailableTime and Asset Size attributes of the corresponding content in the signaling;
• 2) getting the uplink delay Df, downlink delay Dt and bandwidth of the broadband network Bandwidth by the client terminal under the current broadband network through the corresponding method in the network;
• 3) obtaining the available time of the corresponding media content Available Time by a client, normal play time begin and the size of the corresponding content Asset_Size by parsing the signaling;
• 4) if Dt<Threshold, the delay is ignored;
• if Dt>Threshold, the time window for the terminal to send a request and the size of cache assigned by the terminal are calculated by following method:
• calculating a the time required for the service provider to transfer a content unit Data Transfer Time based on the size of a content unit and the bit rate in the current broadband environment;
• if Available Time is “unknown” or there is no such attribute in CI, no processing is performed;
• if Available Time is “anytime”, it is required to skip this step and go to Ĉ;
• if Available Time is a specific UTC time interval, the following judgment is made based on the earliest time:
• Available_Time+Dt+Data_Transfer_Time<begin (1)
• if condition (1) is not met, indicating that the available time of the media content to be transferred is too late and the media content cannot reach the terminal in time under the current network delay, so the part of the content is required to be discarded;
• if condition (1) is met, indicating that the asynchronization problem caused by the current network delay is capable of being resolved through the advanced caching and the calculation in the next step is required;
• calculating the time interval in which the media content is requested by the terminal to be sent in advance:
• wherein:
• Earliest request time:
• Earliest_Request_Time=Available_Time−Df (2)
• Latest request time:
• Latest_Request_Time=begin−DrDf−Data_Transfer_Time (3)
• the actual request time is between these two times:
• Earliest_Request_Time<Actual_Request_Time<Latest_Request_Time (4)
• selecting a request time, the time at which the terminal is capable of beginning to receive the data of the service provider is:
• Receive_Time=Actual_Request_Time+Dt+Df (5)
• the time to receive the data before the time from the terminal to begin is:
• At=begin−Receive_Time (6)
• if Asset_Size attribute is given in CI, the size of the cache window assigned by the terminal is:
• Buffer_Size=min{At*bitrate,Asset_Size} (7)
• if Asset Size attribute is not given in CI, the size of the cache window assigned by the terminal is:
• Buffer_Size=At*bitrate (8).