Method for processing the random access transmission in the frequency domain

1. A method of operating a device in a communication system including a receiver, the method comprising:

generating a random access transmission including a preamble followed by a plurality of zero-valued symbols, whereby a length of the zero-valued symbols corresponds to a sum of a maximum round-trip time for signals between the device and the receiver plus a maximum delay spread of a channel between the device and the receiver, the random access transmission being suitable for processing in a frequency domain by the receiver; and

transmitting the random access transmission to the receiver in the communication system,

wherein the preamble includes a first cyclic prefix,

further wherein the random access transmission comprises a message block, the message block including a second cyclic prefix, whereby the second cyclic prefix is shorter than the first cyclic prefix.

2. The method as claimed in claim 1 , the random access transmission comprises a known training sequence in a trail of the preamble.

3. The method as claimed in claim 2 , wherein at least a portion of the first cyclic prefix comprises a repeat of the known training sequence.

4. The method as claimed in claim 1 , wherein, in the random access transmission, the preamble is preceded by a first plurality of zero-valued symbols.

5. The method as claimed in claim 1 , whereby the second cyclic prefix has a length that is at least equal to the maximum delay spread of the channel between the device and the receiver.

6. The method as claimed in claim 1 , whereby in the random access transmission, the message block ends with a known training sequence.

7. The method as claimed in claim 1 , whereby a length of the second cyclic prefix is such that the second cyclic prefix preceding the message block corresponds to a known training sequence.

8. The method as claimed in claim 1 , whereby the message block precedes the preamble.

9. The method as claimed in claim 8 , whereby the message block is preceded by a second plurality of zero-valued symbols.

10. The method as claimed in claim 1 , whereby the step of generating comprises generating a random access transmission in which the message block follows the preamble.

11. A method as claimed in claim 10 , whereby the message block is followed by a third plurality of zero-valued symbols.

12. A device for use in a communication system including a receiver, the device comprising:

a transmitter for generating and transmitting a random access transmission towards the receiver in order to access the communication system, the random access transmission comprising a preamble followed by a plurality of zero-valued symbols, wherein a length of the zero-valued symbols correspond to a sum of a maximum round-trip time for signals between the device and the receiver plus a maximum delay spread of a channel between the device and the receiver, the random access transmission being suitable for processing in a frequency domain by the receiver in the communication system;

wherein the preamble includes a first cyclic prefix,

further wherein the random access transmission comprises a message block, the message block including a second cyclic prefix, whereby the second cyclic prefix is shorter than the first cyclic prefix.

13. The device as claimed in claim 12 , wherein the transmitter generates the random access transmission such that the preamble is preceded by a first plurality of zero-valued symbols.

14. A method of operating a receiver in a communication system, the method comprising:

receiving, from a user equipment, a random access transmission being formed to allow processing in a frequency domain and including a preamble preceded by a first plurality of zero-valued symbols and/or followed by a second plurality of zero-valued symbols, whereby a length of the first plurality of zero-valued symbols corresponds to a maximum round-trip time for signals between the user equipment and the receiver plus a maximum delay spread of the channel between the user equipment and the receiver; and

processing the received random access transmission in the frequency domain by the steps of

applying a Fourier transform to a portion of the received random access transmission;

calculating a conjugate complex Fourier transform of each of a plurality of preambles in a set of possible preambles, and multiplying each of the calculated Fourier transformed preambles by a result of the applying step;

calculating an inverse Fourier transform of each result from the multiplying step; and

comparing results of the calculating of the inverse Fourier transform step with a threshold to determine which of the possible preambles was used in the random access transmission,

wherein the preamble includes a first cyclic prefix,

further wherein the random access transmission comprises a message block, the message block including a second cyclic prefix, whereby the second cyclic prefix is shorter than the first cyclic prefix.

15. The method as claimed in claim 14 , further comprising the step of determining a received power level at the receiver from the determined preamble.

16. A receiver in a communication system comprising:

a processor for processing in a frequency domain, a random access transmission being formed to allow processing in the frequency domain and including a preamble preceded by a first plurality of zero-valued symbols and followed by a second plurality of zero-valued symbols, said processor adapted to

apply a Fourier transform to a portion of the received random access transmission;

calculate a conjugate complex Fourier transform of each of a plurality of preambles in a set of possible preambles, and multiplying each of the calculated Fourier transformed preambles by a result of the applying step;

calculate an inverse Fourier transform of each result from the multiplying step; and

compare results of the calculating of the inverse Fourier transform with a threshold to determine which of the possible preambles was used in the random access transmission,

wherein the preamble includes a first cyclic prefix,

further wherein the random access transmission comprises a message block, the message block including a second cyclic prefix, whereby the second cyclic prefix is shorter than the first cyclic prefix.