Remote radio unit and baseband unit for asymetric radio area network channel processing

Patent metadata

Field	Value
Publication number	US-2016183248-A1
Application number	US-201414578045-A
Country	US
Kind code	A1
Filing date	Dec 19, 2014
Priority date	Dec 19, 2014
Publication date	Jun 23, 2016
Grant date	—

Abstract

Embodiments describe example radio access networks where uplink and downlink communications operate asymmetrically. In one embodiment, an inverse fast Fourier transform and an add cyclic prefix operation is performed on a downlink communications by a baseband unit. In an uplink communication using the same baseband unit, a corresponding fast Fourier transform and a remove cyclic prefix operation are performed at a remote radio unit. This generates different levels of traffic on a physical communication link between the baseband unit and the remote radio unit for uplink and downlink communications with similar characteristics.

First claim

What is claimed is:

1 . A remote radio unit (RRU) comprising hardware processing circuitry configured to:
receive an uplink communication via an air interface from a user equipment (UE); convert the uplink communication from an uplink time domain signal to an uplink frequency domain signal; communicate the uplink frequency domain signal to a baseband unit (BBU) via a physical communication link; and receive a downlink communication from the BBU via the physical communication link, the downlink communication comprising a downlink time domain signal.

2 . The RRU of claim 1 further comprising:
circuitry configured to remove an uplink cyclic prefix (CP) from the uplink communication; and
uplink radio frequency (RF) filtering circuitry and downlink RF filtering circuitry, wherein the RRU is further configured such that the communication with the UE via the air interface comprises a frequency division duplex communication;
wherein convsersion of the uplink communication from the uplink time domain signal to the uplink frequency domain signal is performed by fast Fourier transform on the uplink communication; and
wherein the downlink communication as received from the BBU includes a downlink CP.

3 . The RRU of claim 2 wherein the RRU is further configured such that the downlink communication is not part of a downlink joint transmission.

4 . The RRU of claim 2 wherein the RRU is further configured with a system bandwidth of between 9-11 MHz, a downlink rate from the BBU of between 90 Mbps and 110 Mbps, a frequency domain I/Q sampling rate of 16 bits, and an uplink rate to the BBU of between 600 Mbps and 800 Mbps.

5 . The RRU of claim 1 further comprising a random access channel (RACH) processing circuitry for uplink channel processing.

6 . The RRU of claim 1 further comprising modulating circuitry, wherein the modulating circuitry comprises FFT circuitry to performs the FFT on the uplink communication and wherein the modulating circuitry is not configured to perform an inverse fast Fourier transform on the downlink communication.

7 . The RRU of claim 1 further comprising an optical input and output, wherein the physical communication link comprises an optical transport network.

8 . The RRU of claim 1 wherein the RRU is configured as a first RRU of a plurality of RRUs in cloud radio access network.

9 . The RRU of claim 1 wherein the RRU is configured to communicate with the BBU as part of a baseband processing pool via a load balancer and switch.

10 . The RRU of claim 1 wherein the downlink CP of the downlink communication is added to the downlink communication by the BBU, wherein the downlink communication is processed and output as the downlink time domain signal by inverse FFT circuitry of the BBU, and wherein the RRU is not configured to add the downlink CP to the downlink communication.

11 . The RRU of claim 1 further comprising a plurality of transmit antennas and a plurality of receive antennas, wherein the RRU is further configured such that the uplink communication is part of an uplink joint transmission.

12 . A baseband unit (BBU) comprising hardware processing circuitry configured to:
receive a downlink communication from a backhaul transport network; perform an inverse fast Fourier transform on the downlink communication to convert the downlink communication to a downlink time domain signal; add a downlink cyclic prefix (CP) to the downlink communication after conversion of the downlink communication to the downlink time domain signal; communicate the downlink time domain signal to a remote radio unit (RRU) via a physical communication link; and receive an uplink communication from the RRU via the physical communication link, wherein the uplink communication comprises a frequency domain signal and wherein the uplink communication does not include an uplink CP.

13 . The BBU of claim 12 further comprising a modulating circuit, wherein the modulating circuit includes an inverse fast Fourier transform modulator circuit that performs the inverse fast Fourier transform, wherein the modulating circuit is not configured for fast Fourier transform processing, wherein the uplink communication as received from the RRU is processed by fast Fourier transform circuitry of the RRU, and wherein the uplink CP is removed from the uplink communication by CP removal circuitry of the RRU.

14 . The BBU of claim 13 further comprising:
a frame and slot signal generation circuit for downlink channel processing; and
a signal distribution and signal processing circuitry for uplink channel processing.

15 . The BBU of claim 14 further comprising:
a transmit power control circuit configured to power control for each physical channel for downlink channel processing and feedback information detection for uplink channel processing.

16 . The BBU of claim 15 further comprising a multiple-input multiple-output (MIMO) system configured for MIMO processing as part of downlink channel processing, and MIMO detection as part of uplink channel processing.

17 . The BBU of claim 16 further comprising:
a channel coding circuit, wherein the channel coding circuit includes a channel coder for downlink channel processing, and a channel decoder for uplink channel processing;
a channel interleaving circuit, wherein the channel interleaving circuit includes a channel interleaver for downlink channel processing, and a channel de-interleaver for uplink channel processing; and
a channel modulation circuit, wherein the channel modulation circuit includes a channel modulator for downlink channel processing, and a channel de-modulator for uplink channel processing.

18 . A method for channel processing on a remote radio unit (RRU) in a radio access network (RAN), comprising:
receiving an uplink frame at the RRU from a first user equipment (UE); processing the uplink frame at the RRU to remove an uplink CP; performing a fast Fourier transform on the uplink frame without the uplink CP to generate a frequency domain signal; communicating the uplink communication following the fast Fourier Transform to a baseband unit (BBU) via a physical communication link; receiving a downlink communication at the RRU from the BBU via the physical communication link, wherein the downlink communication includes a downlink CP; and communicating the downlink communication to the UE without processing the downlink communication at the RRU to adjust the downlink CP of the downlink communication.

19 . The method of claim 19 wherein an interface for the uplink communication is defined by a Common Public Radio Interface (CPRI): Interface specification.

20 . A non-transitory computer readable medium comprising instructions that, when executed by a remote radio unit (RRU), cause the RRU to:
receive an uplink frame via an air interface from a user equipment (UE); convert the uplink frame from an uplink time domain signal to an uplink frequency domain signal; communicate the uplink frequency domain signal to a baseband unit (BBU) via a physical communication link; and receive a downlink frame from the BBU via the physical communication link, the downlink frame comprising a downlink time domain signal.

21 . The non-transitory computer readable medium of claim 20 wherein the instructions further cause the RRU to:
receive the uplink frame at the RRU from a first user equipment (UE);
process the uplink frame at the RRU to remove an uplink CP using CP remover circuitry of the RRU;
perfor

Assignees

• Niu Huaning
• Papathanassiou Apostolos
• Wu Geng

Inventors

• Niu Huaning
• Papathanassiou Apostolos
• Wu Geng

Classifications

• H04W72/20

  Control channels or signalling for resource management · CPC title

• H04W74/0833

  Random access procedures, e.g. with 4-step access · CPC title

• H04W72/0406

  Electricity · mapped topic

• H04W92/10

  between terminal device and access point, i.e. wireless air interface · CPC title

• H04W72/0446 Primary

  Resources in time domain, e.g. slots or frames · CPC title