Radio access networks
Among other things, a communication system comprising at least one remote unit and controller is described. The at least one remote unit wirelessly exchanges radio frequency (RF) signals with mobile devices. Each RF signal comprises information destined for, or originating from, at least one of the mobile devices. The at least two remote units and the controller communicate baseband data corresponding to the information across an intermediate network. The at least two remote units each implement at least some physical layer processing for an air interface used to wirelessly communicate with the subscriber devices. The controller is configured to perform at least some receive signal processing using combined data resulting from combining at least some of the baseband data communicated from more than one of the at least two remote units.
1. A communication system comprising:
at least two remote units to wirelessly exchange radio frequency (RF) signals with subscriber devices, each RF signal comprising information that is destined for, or originating from, at least one of the subscriber devices; and
a controller communicatively coupled to the at least two remote units;
wherein the at least two remote units and the controller communicate baseband data corresponding to the information across an intermediate network;
wherein the at least two remote units each implement at least some physical layer processing for an air interface used to wirelessly communicate with the subscriber devices; and
wherein the controller is configured to perform at least some receive signal processing using combined data resulting from combining at least some of the baseband data communicated from more than one of the at least two remote units.
2. The communication system of claim 1 , wherein the controller is configured to combine said at least some of the baseband data communicated from said more than one of the at least two remote units.
3. The communication system of claim 2 , wherein the controller combines by performing Maximal Ratio Combining (MRC), Interference Rejection Combining (IRC), or Successive Interference Cancellation (SIC) across the baseband data received at two or more of the remote units.
4. The communication system of claim 1 , wherein each of the at least two remote units implement the at least some physical layer processing by removing cyclic prefix from time-domain IQ samples in received OFDM symbols.
5. The communication system of claim 4 , wherein each of the at least two remote units implement the at least some physical layer processing by further applying Fast Fourier Transform (FFT) to produce frequency-domain IQ symbols.
6. The communication system of claim 1 , wherein each of the at least two remote units implement the at least some physical layer processing by quantizing frequency-domain IQ symbols in Ethernet frames to send to the controller.
7. The communication system of claim 6 , wherein the quantizing is tailored based on whether uplink communications are physical uplink shared channel (PUSCH), physical uplink control channel (PUCCH), sounding reference signal (SRS), or physical random access channel (PRACH) communications.
8. The communication system of claim 1 , wherein each of the at least two remote units implement the at least some physical layer processing by converting received time-domain IQ symbols received on a physical random access channel (PRACH) into a lower-rate time-domain sequence using a time-domain frequency shift, decimating the lower-rate time-domain sequence, and converting a resulting sequence into frequency domain by applying Fast Fourier Transform (FFT).
9. The communication system of claim 1 , wherein each of the at least two remote units implement the at least some physical layer processing by applying inverse FFT (IFFT) and inserting cyclic prefixes before sending RF signals to the subscriber devices.
10. The communication system of claim 9 , wherein each of the at least two remote units implement the at least some physical layer processing by further reconstructing quantized frequency-domain IQ symbols from the controller.
11. The communication system of claim 1 , wherein the intermediate network is an Ethernet network.
12. A method comprising:
wirelessly exchanging, by at least two remote units, radio frequency (RF) signals with subscriber devices, each RF signal comprising information that is destined for, or received from, at least one of the subscriber devices;
communicating baseband data corresponding to the information between a controller and the at least two remote units across an intermediate network;
performing, at the at least two remote units, at least some physical layer processing for an air interface used to wirelessly communicate with the subscriber devices; and
performing, at the controller, at least some receive signal processing using combined data resulting from combining at least some of the baseband data communicated from more than one of the at least two remote units.
13. The method of claim 12 , further comprising combining, at the controller, said at least some of the baseband data communicated from said more than one of the at least two remote units.
14. The method of claim 13 , wherein the combining comprises performing Maximal Ratio Combining (MRC), Interference Rejection Combining (IRC), or Successive Interference Cancellation (SIC) across the baseband data received at two or more of the remote units.
15. The method of claim 12 , wherein the at least some physical layer processing comprises removing cyclic prefix from time-domain IQ samples in received OFDM symbols.
16. The method of claim 15 , wherein the at least some physical layer processing further comprises applying Fast Fourier Transform (FFT) to produce frequency-domain IQ symbols.
17. The method of claim 12 , wherein the at least some physical layer processing comprises quantizing frequency-domain IQ symbols in Ethernet frames to send to the controller.
18. The method of claim 17 , wherein the quantizing is tailored based on whether uplink communications are physical uplink shared channel (PUSCH), physical uplink control channel (PUCCH), sounding reference signal (SRS), or physical random access channel (PRACH) communications.
19. The method of claim 12 , wherein the at least some physical layer processing comprises converting received time-domain IQ symbols received on a physical random access channel (PRACH) into a lower-rate time-domain sequence using a time-domain frequency shift, decimating the lower-rate time-domain sequence, and converting a resulting sequence into frequency domain by applying Fast Fourier Transform (FFT).
20. The method of claim 12 , wherein the at least some physical layer processing comprises applying inverse FFT (IFFT) and inserting cyclic prefixes before sending RF signals to the subscriber devices.
21. The method of claim 20 , wherein the at least some physical layer processing comprises reconstructing quantized frequency-domain IQ symbols from the controller.
22. The method of claim 12 , wherein the intermediate network is an Ethernet network.