Method for operating a cache arranged along a transmission path between client terminals and at least one server, and corresponding cache

1. A method for operating a cache configured to be arranged along a transmission path between a plurality of client terminals and at least one server, comprising:

requesting a first ongoing representation of a segment of a multimedia content from the at least one server, based on a first request from a first client terminal of the plurality of client terminals;

receiving, from a second client terminal of the plurality of client terminals, a second request comprising a preferred representation and at least one alternative representation of the segment of the multimedia content, while receipt of the first ongoing representation at the cache, from the at least one server, is pending download completion; and

determining that the first ongoing representation matches at least one of the preferred representation or the alternative representation of the second request.

2. The method according to claim 1 , further comprising: determining a first value of a usefulness function associated with the first ongoing representation; and

transmitting, to the second client terminal, the first ongoing representation, when the first value of the usefulness function meets a performance criterion.

3. The method according to claim 2 , further comprising:

receiving a second ongoing representation of the segment of a multimedia content from the at least one server prior to receiving the second request;

determining that the second ongoing representation matches at least one of the preferred representations or an alternative representation of the second request;

determining a second value of the usefulness function associated with the second ongoing representation.

4. The method according to claim 3 , further comprising requesting the preferred representation of the second request from the server when neither the first value of the usefulness function nor the second value of the usefulness function meets the performance criterion.

5. The method according to claim 3 , further comprising transmitting the second ongoing representation when the second value of usefulness function is greater than the first value of usefulness function.

6. The method according to claim 2 , wherein the performance criterion is met when the value of the usefulness function exceeds zero.

7. The method according to claim 2 , wherein the usefulness function depends on a mode of operation is selected from one of:

an aggressive mode wherein the value of usefulness function is equal to a constant,

a fast mode wherein the usefulness function is based on the delivery time from the server of the preferred representation of the second request and the delivery time of the first ongoing representation, and

a quality mode wherein the usefulness function is based on the quality of the preferred representation of the second request and the quality of one of a plurality of matched ongoing representation already requested, the plurality of matched ongoing representations comprising the first ongoing representation.

8. The method according to claim 7 , wherein the mode of operation is determined based on at least one network parameter.

9. The method according to claim 7 , wherein the mode of operation is determined by the second client terminal and is indicated within the second request.

10. A network equipment comprising a cache adapted to be located along a transmission path between a plurality of client terminals and at least one server, comprising:

a receiver configured to receive a first ongoing representation of a segment of a multimedia content from the at least one server, based on a first request from a first client terminal of the plurality of client terminals;

an interface of connection for receiving, from a second client terminal of the plurality of client terminals, a second request for a preferred representation and at least one alternative representation of the segment of said multimedia content while receipt of the first ongoing representation at the cache, from the at least one server, is pending download completion; and

a matching module configured to determine that the first ongoing representation matches at least one of the preferred representation or an alternative representation of the second request.

11. The network equipment according to claim 10 , wherein the cache further comprises a calculator adapted to determine a first value of a usefulness function associated with the first ongoing representation.

12. The network equipment according to claim 11 , wherein the receiver is further configured to receive a second ongoing representation of the segment of a multimedia content from the at least one server prior to receiving the second request;

wherein the matching module is further configured to determine that the second ongoing representation matches at least one of the preferred representations or an alternative representation of the second request; and

wherein the calculator is further adapted to determine a second value of the usefulness function associated with the second ongoing representation.

13. The network equipment according to claim 11 , wherein the cache further comprises a comparator configured to select one of the first ongoing representation or the second ongoing representation based on determining whether the second value of the usefulness function is higher than the first value of the usefulness function.

14. The network equipment according to claim 12 , wherein the cache further comprises a comparator configured to select one of the first ongoing representation or the second ongoing representation and the to determine that the selected first or second value of the usefulness function meets a performance criterion.

15. A client terminal configured to receive a multimedia content divided into segments and provided by at least one remote server, each segment being available in one or more representations, the client terminal comprising:

a communication module configured to send a request for a representation, the request comprising a selected mode of operation to be applied by a cache arranged along a transmission path between said client terminal and at least one remote server, and

wherein the cache is configured to receive and concurrently processing concurrent requests for one or more particular segments of the segments of multimedia content available in one or more representations from the client terminal while receipt of the one or more particular segments, as requested by a second client terminal, is pending download completion.