Random access design for high doppler in wireless network

1. A method for transmitting in a cellular network, comprising:

receiving information by a user equipment (UE) within a given cell that designates a particular access slot as either a high-speed access slot or a low-speed access slot; and

transmitting a signal from the UE to a NodeB using a selected structure, such that a baseline structure is transmitted only in the designated low-speed access slot and that an alternate structure is transmitted only in the designated high-speed access slot, wherein transmitting by UE is permitted in both the high-speed access slot and in the low-speed access slot if the relative speed is less than a threshold value, and wherein transmitting by the UE is permitted only in the high-speed access slot if the relative speed exceeds the threshold value.

2. The method of claim 1 where both the baseline structure and the alternate structure each comprise a preamble.

3. The method of claim 2 , wherein a baseline preamble structure defines a single preamble sequence that is a cyclic shifted constant amplitude zero autocorrelation (CAZAC) sequence and an alternate preamble structure defines a preamble sequence that is a shortened version of the cyclic shifted CAZAC sequence that is repeated one or more times.

4. The method of claim 2 , wherein a plurality of slots are for non-synchronized random access (RA) requests and a different plurality of slots are for scheduling requests (SR).

5. The method of claim 1 , further comprising receiving a command from the NodeB that authorizes the UE to use an alternate preamble structure, wherein the alternate preamble structure is not selected if not authorized.

6. The method of claim 1 , further comprising:

determining a relative speed of the UE to a serving base station within the cell.

7. The method of claim 6 , wherein the UE determines the relative speed based on correlation measurements performed on a downlink (DL) pilot broadcast by the NodeB.

8. The method of claim 7 , further comprising:

receiving a selected preamble structure at the NodeB;

performing two accumulation schemes in parallel on a received preamble structure during a high-speed request slot, wherein the first accumulation scheme performs one coherent accumulation of power delay profiles over a total preamble duration, and wherein the second accumulation sequence performs non-coherent accumulation of power delay profiles resulting from each repeated preamble sequence; and

recovering a transmitted preamble sequence from one of the two accumulation schemes if a sample position in either accumulation power delay profile exceeds a detection threshold.

9. A user equipment (UE) for use in a cellular network, comprising:

means for receiving information by the UE within a given cell that designates a particular access slot as either a high-speed access slot and or a low-speed access slot;

means for selecting either a baseline structure or an alternate structure;

means for transmitting a signal from the UE to a NodeB using the selected structure, such that the baseline structure is transmitted only in the designated low-speed access slot and that the alternate structure is transmitted only in the designated high-speed access slot;

means for determining a relative speed of the UE to a serving base station within the cell; and

means for selecting either the baseline structure or the alternate structure if the relative speed is less than a threshold value or only the alternate structure if the relative speed exceeds the threshold value.

10. The UE of claim 9 where both baseline and alternate structures each comprise a preamble.

11. The UE of claim 9 , further comprising means for permitting transmission in both the high-speed access slot and in the low-speed access slot if the relative speed is less than the threshold value; and

means for permitting transmission by the UE only in the high-speed access slot if the relative speed exceeds the threshold value.

12. A cellular telephone for use in a cellular network, comprising:

a receiver connected to an antenna operable to receive information within a given cell that designates a particular access slot as either a high-speed access slot or a low-speed access slot;

a processor connected to a storage memory holding instructions for execution by the processor and connected to obtain signals from the receiver, wherein the processor is operable to select either a baseline structure or an alternate structure, wherein the processor is operable to determine a relative speed of the UE to a serving base station within the cell; and wherein the processor is operable to select either a baseline structure or an alternate structure if the relative speed is less than a threshold value or only an alternate structure if the relative speed exceeds the threshold value; and

a transmitter connected to the processor operable to transmit a signal from the cellular telephone to a NodeB using the selected structure, such that the baseline structure is transmitted only in the designated low-speed access slot and that the alternate structure is transmitted only in the designated high-speed access slot.

13. The cellular telephone of claim 12 where both baseline and alternate structures each comprise a preamble.

14. The cellular telephone of claim 13 , wherein the processor is further operable to form a baseline preamble structure that is a single preamble sequence by selecting a constant amplitude zero autocorrelation (CAZAC) sequence and then cyclic shifting the CAZAC sequence a determined amount and further operable to form an alternate preamble structure by selecting a shortened CAZAC sequence, cyclic shifting the shortened CAZAC sequence and then repeating the cyclic shifted shortened CAZAC sequence one or more times.

15. The cellular telephone of claim 14 , wherein the processor determines the relative speed based on correlation measurements performed on a downlink (DL) pilot broadcast to the receiver by the NodeB.

16. A method for transmitting in a cellular network, comprising:

transmitting information to UE within a given cell that designates a particular access slot as either a high-speed access slot or a low-speed access slot;

receiving a signal at a serving base station of the given cell from the UE using a selected structure, such that a baseline structure is received only in the designated low-speed access slot and that an alternate structure is received only in the designated high-speed access slot;

determining if each given cell will support high-speed UE based on geographical constraints of the cell;

compiling a database to retain the determination for each cell in a portion of the a network; and

transmitting the determination for each given cell to a NodeB that serves the given cell.

17. The method of claim 16 wherein all access slots for a given NodeB are designated as either low-speed access slots or high-speed access slots.

18. The method of claim 16 , wherein both the baseline structure and the alternate structure each comprise a preamble.

19. The method of claim 18 wherein a baseline preamble structure defines a single preamble sequence that is a cyclic shifted constant amplitude zero autocorrelation (CAZAC) sequence and an alternate preamble structure defines a preamble sequence that is a shortened version of the cyclic shifted CAZAC sequence that is repeated one or more times.

20. The method of claim 18 , further comprising:

performing two accumulation schemes in parallel on a received preamble structure during a high-speed slot, wherein the first accumulation scheme performs one coherent accumulation of power delay profiles over a total preamble duration, and wherein the second accumulation sequence performs non-coherent accumulation of power delay profiles resulting from each repeated preamble sequence; and

recovering the transmitted preamble sequence from one of the two accumulation schemes if a sample position in either accumulation power delay profile exceeds a detection threshold.

21. The method of claim 16 wherein a plurality of slots are for non-synchronized random access (RA) requests and a different plurality of slots are for scheduling requests (SR).