Frequency hopping

A communications system comprising:

• a communications node and a plurality of user devices operable to communicate with the communications node over a communications channel;
• wherein the communications channel includes a transmission bandwidth, having a plurality of frequency resources, that is divided into a plurality of contiguous sub-bands each having N frequency resources;
• wherein each user device has a respective allocation of said frequency resources to use for communications with said communications node, the allocation of said frequency resources comprising a set of contiguously allocated resource blocks;
• and wherein each user device is operable to apply a frequency shift to its set of contiguously allocated resource blocks in accordance with a frequency hopping sequence to determine frequency resources to use for communicating information with the other communications node and in accordance with the following equation:
• y={x+a(t)N} mod NRB
• where
• NRB is the total number of frequency resource blocks in the transmission band
• N is the number of contiguous frequency resource blocks in each sub-band
• x is the set of contiguously allocated resource blocks
• y is the frequency hopped resource
• t is a time counter
• a(t) is the frequency hopping shift applied at time point t, and is an integer value from the set {0, 1, . . . , S−1};
• and
• S is the number of sub-bands.

A method performed in a communications node which communicates with another communications node over a communications channel having a plurality of frequency resources, the communications node comprising:

• defining a division of the communications channel into a plurality of contiguous sub-bands each having N frequency resources;
• defining an allocation of said frequency resources comprising a set of contiguously allocated resource blocks;
• applying a frequency shift to the set of contiguously allocated resource blocks in accordance with a frequency hopping sequence to determine frequency resources to use for communicating information with the other communications node and in accordance with the following equation:
• y={x+a(t)N} mod NRB
• where
• NRB is the total number of frequency resource blocks in the transmission band
• N is the number of contiguous frequency resource blocks in each sub-band
• x is the set of contiguously allocated resource blocks
• y is the frequency hopped resource
• t is a time counter
• a(t) is the frequency hopping shift applied at time point t, and is an integer value from the set {0, 1, . . . , S−1};
• and
• S is the number of sub-bands;
• and
• a transceiver for communicating information with the other communications node using the determined frequency resource;
• and communicating information with the other communications node using the determined frequency resource.