Method of processing a digital signal for transmission, a method of processing an optical data unit upon reception, and a network element for a telecommunications network

1. A method of processing a digital signal, including at least digital radio data frames, for transmission, the method comprising:

compressing digital data frames, wherein the compressing comprises reducing redundancies in the digital data frames, scaling a block of samples output from the reducing by a scaling factor and quantising the scaled samples to produce scaled, compressed samples; and

generating, via at least one processor, an optical data unit for transmission comprising multiple of the compressed digital data frames, said multiple of the compressed digital data frames being from multiple links and the optical data unit being configured for transport by an Optical Transport Network, OTN, wherein the compressed digital data frames are concatenated into a plurality of composite frames, and the composite frames are encapsulated to form a respective optical data unit and wherein the generation is by concatenating multiple of the compressed digital data frames into a composite frame and encapsulating the composite frame to form the optical data unit.

2. The method according to claim 1 , in which the digital radio data frames are Common Public Radio Interfaces (CPRI), data frame, and the links are CPRI links.

3. The method of processing according to claim 1 , in which the optical data unit is an ODU2 in accordance with ITU-T Recommendation G.709.

4. A method of processing an optical data unit upon reception from an Optical Transport Network, OTN, by

splitting the optical data unit into multiple compressed digital data frames, wherein the splitting is by de-encapsulating the optical data unit to provide a composite data frame, and deconcatenating the composite data frame to provide the multiple compressed digital data frames; and

decompressing the compressed digital data frames to provide decompressed digital radio data frames from multiple links, wherein the decompressing comprises dequantising received samples, descaling a block of the dequantised samples, and inserting redundancies into the descaled samples to produce the digital radio data frames.

5. The method of processing according to claim 4 , further comprising:

receiving multiple optical data units; and

de-encapsulating the multiple optical data units that are received to provide respective multiple composite data frames, and

de-concatenating the respective multiple composite data frames into a plurality of digital data frames.

6. The method of processing according to claim 4 , in which the digital radio data frames are Common Public Radio Interfaces (CPRI), data frame, and the links are CPRI links.

7. The method of processing according to claim 4 , in which the optical data unit is an ODU2 in accordance with ITU-T Recommendation G.709.

8. A network element for a telecommunications network, the element comprising:

a compressor configured to compress digital radio data frames from multiple links wherein compressing comprises reducing redundancies in the digital data frames, scaling a block of samples output from the reducing by a scaling factor and quantisinq the scaled samples to produce scaled, compressed samples;

a generator configured to generate a first optical data unit for transmission comprising multiple of the compressed digital data frames, the first optical data unit being configured for transport by an Optical Transport Network, OTN, wherein generation is by concatenating multiple of the compressed digital data frames into a composite frame and encapsulating the composite frames as a first optical data unit;

a processor configured to split a second optical data unit upon reception from an Optical Transport Network, OTN, into multiple compressed digital data frames; and

a decompressor configured to decompress the compressed digital data frames from the second optical data unit so as to provide digital radio data frames from multiple links, wherein decompressing comprises dequantising received samples, descaling a block of the dequantised samples, and inserting redundancies into the descaled samples to produce the digital radio data frames.

9. The network element according to claim 8 , in which said splitting is by de-encapsulating the second optical data unit to provide a composite data frame, and deconcatenating the composite data frame to provide multiple of the compressed digital data frames.

10. The network element according to claim 8 , in which each digital radio data frame is a Common Public Radio Interface, CPRI, data frame, the links are CPRI links and in which the optical data units are ODU2 in accordance with ITU-T Recommendation G.709.

11. A telecommunications network comprising a number of network elements according to claim 8 connected between an Optical Transport Network and a number of base band units, in which the number of base band units is greater than the number of network elements.

12. The telecommunications network comprising a number of network elements according to claim 8 connected between an optical Transport Network and a number of base band units, in which the number of base band units is less than the number of network elements.

13. The telecommunications network comprising a plurality of network elements according to claim 8 connected between the Optical Transport Network and a plurality of base band units, in which at least one of the network elements is configured to be switchably connectable to a plurality of the base band units dependent upon time of day.