Resource allocation

1. A method of allocating resources in a communication system which uses a plurality of sub-carriers arranged in a sequence of physical resource blocks, wherein adjacent blocks of said sequence are arranged in groups, in a base station the method comprising:

determining at least one virtual resource block for allocation to a mobile communications device;

signalling data identifying each virtual resource block to said mobile communications device; and

mapping each allocated virtual resource block, using predetermined mapping data, onto a plurality of spaced physical resource blocks to determine the physical resource blocks to be used for communications with the mobile communications device,

wherein at least part of said predetermined mapping data defines an equation for a location of a further physical resource block, relative to a first physical resource block, and

wherein the equation for the location of a further physical resource block can be represented as follows:

I PRB =( x +gap)mod 2*gap

where I PRB is an index of the further physical resource block, x is an index of the first physical resource block and gap is a spacing.

2. A method according to claim 1 , wherein said predetermined mapping data defines the spacing to be a function of the number of physical resource blocks represented by the virtual resource block.

3. A method according to claim 1 , wherein said predetermined mapping data defines the spacing to be a function of the number of physical resource blocks in said sequence.

4. A method according to claim 1 , wherein at least part of said predetermined mapping data defines an equation for the spacing, and

wherein said equation for the spacing is:

gap

=

⌊

G

Nd

⌋

*

P

2

where

G

=

⌈

N

RB

DL

P

2

⌉

where gap is the spacing, P is the number of physical resource blocks in each group, Nd is the number of physical resource blocks which the virtual resource block represents, N RB DL is the number of physical resource blocks in the sequence, └ ┘ is the floor function and ┌ ┐ is the ceiling function.

5. A method according to claim 1 , wherein at least part of said predetermined mapping data defines a look-up table.

6. A method according to claim 1 , wherein said signalled data represents an index of the allocated virtual resource block.

7. A method performed by a mobile communications device which operates in a communication system that uses a plurality of sub-carriers arranged in a sequence of physical resource blocks, wherein adjacent blocks of said sequence are arranged in groups, the method comprising:

receiving data identifying one or more virtual resource blocks allocated to the mobile communications device; and

mapping each allocated virtual resource block, using predetermined mapping data, onto a plurality of spaced physical resource blocks to determine the physical resource blocks to be used for communications with a base station,

wherein at least part of said predetermined mapping data defines an equation for a location of a further physical resource block, relative to a first physical resource block, and

wherein the equation for the location of a further physical resource block can be represented as follows:

I PRB =( x +gap)mod 2*gap

where I PRB is an index of the further physical resource block, x is an index of the first physical resource block and gap is a spacing.

8. A method according to claim 7 , wherein said predetermined mapping data defines the spacing to be a function of the number of physical resource blocks represented by the virtual resource block.

9. A method according to claim 8 , wherein said predetermined mapping data defines the spacing to be a function of the number of physical resource blocks in said sequence.

10. A method according to claim 8 , wherein at least part of said predetermined mapping data defines an equation for the spacing, and

wherein equation for the spacing is:

gap

=

⌊

G

Nd

⌋

*

P

2

where

G

=

⌈

N

RB

DL

P

2

⌉

where gap is the spacing, P is the number of physical resource blocks in each group, Nd is the number of physical resource blocks which the virtual resource block represents, N RB DL is the number of physical resource blocks in the sequence, └ ┘ is the floor function and ┌ ┐ is the ceiling function.

11. A method according to claim 8 , wherein at least part of said predetermined mapping data defines a look-up table.

12. A method according to claim 8 , wherein said received data represents an index of the allocated virtual resource block.

13. A base station for use in a communication system which uses a plurality of sub-carriers arranged in a sequence of physical resource blocks wherein adjacent blocks of said sequence are arranged in groups, the base station comprising:

a processor for determining at least one virtual resource block for allocation to a mobile communications device;

a transmitter for signalling data identifying each virtual resource block to said mobile communications device; and

a mapper for mapping each allocated virtual resource block, using predetermined mapping data, onto a plurality of spaced physical resource blocks to determine the physical resource blocks to be used for communications with the mobile communications device,

wherein at least part of said predetermined mapping data defines an equation for a location of a further physical resource block, relative to a first physical resource block, and

wherein the equation for the location of a further physical resource block can be represented as follows:

I PRB =( x +gap)mod 2*gap

where I PRB is an index of the further physical resource block, x is an index of the first physical resource block and gap is a spacing.

14. A mobile communications device which operates in a communication system that uses a plurality of sub-carriers arranged in a sequence of physical resource blocks, wherein adjacent blocks of said sequence are arranged in groups, the mobile communications device comprising:

a receiver for receiving data identifying one or more virtual resource blocks allocated to the mobile communications device; and

a mapper mapping each allocated virtual resource block, using predetermined mapping data, onto a plurality of spaced physical resource blocks to determine the physical resource blocks to be used for communications with a base station,

wherein at least part of said predetermined mapping data defines an equation for a location of a further physical resource block, relative to a first physical resource block, and

wherein the equation for the location of a further physical resource block can be represented as follows:

I PRB =( x +gap)mod 2*gap

where I PRB is an index of the further physical resource block, x is an index of the first physical resource block and gap is a spacing.

15. A method performed by a communications device which operates in a communication system that uses a plurality of sub-carriers arranged in a sequence of physical resource blocks, wherein adjacent blocks of said sequence are arranged in groups, the method comprising:

obtaining data identifying one or more allocated virtual resource blocks; and

mapping each allocated virtual resource block, using predetermined mapping data, onto a plurality of spaced physical resource blocks to determine the physical resource blocks to be used for communications,

wherein at least part of said predetermined mapping data defines an equation for a location of a further physical resource block, relative to a first physical resource block, and

wherein the equation for the location of a further physical resource block can be represented as follows:

I PRB =( x +gap)mod 2*gap

where I PRB is an index of the further physical resource block, x is an index of the first physical resource block and gap is a spacing.

16. A method according to claim 15 , performed by a mobile communications device and wherein said obtaining comprises receiving the data identifying the one or more allocated virtual resource blocks.

17. A method according to claim 15 , performed by a base station and wherein said obtaining comprises determining the data identifying the one or more allocated virtual resource blocks.