A network element may provide a plurality of user equipments with a dedicated pilot sequence for uplink reference signal transmission. A user equipment may, after receipt of a dedicated pilot sequence, spread the pilot sequences using a block spreading method.
1. A method comprising:
providing each of a plurality of a user equipments in a communication system with a dedicated pilot sequence for reference signal transmission that is based on a block spreading method;
coordinating among adjacent cells such that each user equipment is allocated a unique combination of shifted dedicated pilot sequence and block spreading code; and
receiving from at least some of the plurality of user equipments transmissions using the block spreading method and comprising the provided pilot sequences.
2. A method according to claim 1 , comprising providing the dedicated pilot sequences for uplink reference signal transmissions wherein orthogonal codes are used in the block spreading method.
3. A method according to claim 1 , wherein the pilot sequences in at least some of the received transmissions are spread over one uplink transmission interval comprising four short blocks.
4. A method according to claim 3 , wherein the uplink transmission interval during which at least some of the transmissions are received in the method comprises two sub-frames.
5. A method according to claim 1 , wherein each dedicated pilot sequence comprises a Constant Amplitude Zero AutoCorrelation (CAZAC) sequence.
6. A method according to claim 5 , wherein each Constant Amplitude Zero AutoCorrelation (CAZAC) sequence has a dedicated frequency pin allocation.
7. A method according to claim 5 , wherein each Constant Amplitude Zero AutoCorrelation (CAZAC) sequence has a defined cyclic shift of a single Constant Amplitude Zero AutoCorrelation (CAZAC) code.
8. A method comprising:
receiving at a user equipment a dedicated pilot sequence; and
the user equipment spreading the pilot sequence in an uplink reference signal transmission using a block spreading method; wherein a different combination of shifted dedicated pilot sequence and block spreading code is used in the user equipment than is used by any other user equipment in any adjacent cell.
9. A method according to claim 8 , wherein the block spreading method comprises spreading the pilot sequence using an orthogonal code.
10. A method according to claim 9 , wherein the pilot sequence is spread using a Hadamard code.
11. A method according to claim 9 , wherein the pilot sequence is spread using a Generalized Chirp-Like code.
12. A method according to claim 8 , wherein the pilot sequence is spread over one uplink transmission interval comprising four short blocks.
13. A method according to claim 8 , wherein an uplink transmission interval in the method comprises two sub-frames.
14. A method according to claim 8 , wherein the dedicated pilot sequence comprises a Constant Amplitude Zero AutoCorrelation (CAZAC) sequence.
15. A method according to claim 14 , wherein the Constant Amplitude Zero AutoCorrelation (CAZAC) sequence has a dedicated frequency pin allocation.
16. A method according to claim 14 , wherein the CAZAC sequence has a defined cyclic shift of a single CAZAC code.
17. A communication system comprising at least a network element comprising at least a processor and at least one memory storing computer program instructions that are configured to cause the network element to coordinate with adjacent cells so as to provide each of user equipments operating in the adjacent cells with a unique combination of block spreading code and dedicated pilot sequence for uplink reference signal transmission.
18. A communication system comprising at least a network element comprising at least a processor and at least one memory storing computer program instructions that are configured to cause the network element to perform a channel estimation operation based on time averaging, wherein an averaging length of a channel estimation filter is N multiplied by length of a block-level spreading code, where, N=[½, 1, 2, 3 . . . ].