Method for communicating in mobile system

A primary station comprising means for communicating with a plurality of secondary stations, the primary station further comprising:

• allocating means to allocate at least one resource set to a given secondary station into at least one of a plurality of search spaces, each search space comprising at least one resource set, wherein the search space of the given secondary station is determined on the basis of a hash function fs(x);
• wherein x∈X, s∈{0, 1, . . . , T−1} into {0, 1, . . . , M−1}, wherein x corresponds to a parameter of the secondary station, and s corresponds to a subframe number, and X is the range of the hash, and T indicates a quantity of hash functions, and M is a number in a series of numbers that are all different from each other, and wherein the hash function has the following properties:
• for each s∈{0, 1, . . . , T−1}, the function fs attains each element in {0, 1, . . . , M−1} approximately equally often;
• for all distinct s,t in {0, 1, . . . , T−1}, where t is a different subfrarne than s, the number of elements x in X is such that fs(x)=i and ft(x)=j is approximately the same for all values of i and j.

A secondary station comprising means for communicatinz with a primary station, the secondary station further comprising

• control means configured to search at least one of a plurality of search spaces, each search space comprising at least one resource set, where at least one resource set might be used to transmit a message to the considered secondary station, wherein the search space of the secondary station is determined on the basis of a hash function fs(x) wherein x∈X, s∈{0, 1, . . . , T−1} into {0, 1, . . . , M−1}, whereon x corresponds to a parameter of the secondary station, and s corresponds to a subframe number, and X is the range of the hash, and T indicates a quantity of hash functions, and M is a number in a series of numbers that are all different from each other, and wherein the hash function has the following properties:
• for each s∈{0, 1, . . . , T−1}, the function fs attains each element in {0, 1, . . . , M−1} approximately equally often;
• for all distinct s,t in {0, 1, . . . . , T−1} where t is a different subframe than s, the number of elements x in X is such that fs(x)=i and ft(x)=j is approximately the same for all values of i and j;
• and
• wherein the control means are configured formearching in the configured at least one search space for a control message from the primary station addressed to the considered secondary station, and receiving the control message.