Digital Representations of Analog Signals and Control Words Using Different Multi-Level Modulation Formats

Patent metadata

Field	Value
Publication number	US-2016308641-A1
Application number	US-201514853478-A
Country	US
Kind code	A1
Filing date	Sep 14, 2015
Priority date	Apr 17, 2015
Publication date	Oct 20, 2016
Grant date	—

Abstract

A method implemented by a transmitter, comprising encoding digital in-phase and quadrature-phase (IQ) data associated with a plurality of analog signals according to a first multi-level modulation format to produce a modulated IQ signal, encoding control information associated with the plurality of analog signals according to a second multi-level modulation format that is different from the first multi-level modulation format to produce a modulated control signal, aggregating the modulated IQ signal and the modulated control signal via time-division multiplexing (TDM) to produce an aggregated TDM signal, and transmitting the aggregated TDM signal over a communication channel.

First claim

What is claimed is:

1 . A method implemented by a transmitter, comprising:
encoding digital in-phase and quadrature-phase (IQ) data associated with a plurality of analog signals according to a first multi-level modulation format to produce a modulated IQ signal; encoding control information associated with the plurality of analog signals according to a second multi-level modulation format that is different from the first multi-level modulation format to produce a modulated control signal; aggregating the modulated IQ signal and the modulated control signal via time-division multiplexing (TDM) to produce an aggregated TDM signal; and transmitting the aggregated TDM signal over a communication channel.

2 . The method of claim 1 , wherein the first multi-level modulation format is a pulse-code modulation (PCM) format, and wherein the second multi-level modulation format is a predetermined modulation format that enables estimation and equalization of the communication channel.

3 . The method claim of 2 , wherein the predetermined modulation format is a quadrature amplitude modulation (QAM)-based modulation format.

4 . The method claim of 2 , wherein the predetermined modulation format is a trellis-coded modulation (TCM) format.

5 . The method claim of 1 , wherein the IQ data is further associated with a digital baseband (BB) representation of the plurality of analog signals.

6 . The method claim of 1 , wherein the IQ data is further associated with a digital intermediate-frequency (IF) representation of the plurality of analog signals.

7 . The method of claim 1 , wherein the modulated IQ signal comprises modulated IQ data symbols, wherein the modulated control signal comprises modulated control information symbols, and wherein the aggregating the modulated IQ signal and the modulated control signal further comprises periodically inserting at least some of the modulated control information symbols between some of the modulated IQ data symbols to produce a time-domain symbol sequence.

8 . The method of claim 7 , further comprising adding a training symbol (TS) to the time-domain symbol sequence to enable synchronization and detection of the time-domain symbol sequence.

9 . The method of claim 7 , further comprising adding one or more stuffing bits to the time-domain symbol sequence to match a transmission rate.

10 . The method of claim 1 , further comprising:
aggregating the digital IQ data through the TDM to produce an aggregated IQ data sequence; and aggregating the control information through the TDM to produce an aggregated control sequence, wherein the encoding the digital IQ data comprises encoding the aggregated IQ data sequence according to the first multi-level modulation format to produce the modulated IQ signal, and wherein the encoding the control information comprises encoding the aggregated control sequence according to the second multi-level modulation format to produce the modulated control signal.

11 . The method of claim 1 , wherein the communication channel comprises an optical fiber link, a cable link, or a free-space link.

12 . The method of claim 1 , wherein the communication channel is a wireless fronthaul link, and wherein the plurality of analog signals corresponds to a plurality of antenna-carrier channel signals in a radio access network (RAN).

13 . An apparatus comprising:
a processor configured to:
encode digital in-phase and quadrature-phase (IQ) data associated with a plurality of analog wireless signals according to a first multi-level modulation format to produce a modulated IQ signal;
encode control words (CWs) comprising control information associated with the plurality of analog wireless signals according to a second multi-level modulation format that is different from the first multi-level modulation format to produce a modulated CW signal; and
aggregate the modulated IQ signal and the modulated CW signal through time-division multiplexing (TDM) to produce an aggregated TDM signal; and
a frontend coupled to the processor and configured to transmit the aggregated TDM signal over a communication link.

14 . The apparatus of claim 13 , wherein the first multi-level modulation format is a pulse-code modulation (PCM) format, and wherein the second multi-level modulation formation is a predetermined quadrature amplitude modulation (QAM)-based modulation format.

15 . The apparatus of claim 13 , wherein the apparatus is a wireless fronthaul remote radio unit (RRU), and wherein the analog wireless signals are uplink (UL) signals.

16 . The apparatus of claim 13 , wherein the apparatus is a wireless fronthaul baseband unit (BBU), and wherein the analog wireless signals are downlink (DL) signals.

17 . An apparatus comprising:
a frontend configured to receive a single-carrier signal carrying a multiplexed signal comprising an in-phase and quadrature-phase (IQ) data portion and a control word (CW) portion, wherein the IQ data portion comprises digital IQ data associated with a plurality of analog wireless signals, and wherein the CW portion comprises CWs comprising control information associated with the plurality of analog wireless signals; and a processor coupled to the frontend and configured to:
update a channel equalizer according to the CW portion;
perform channel equalization on the multiplexed signal according to the channel equalizer;
obtain the digital IQ data from the IQ data portion according to a first multi-level modulation format; and
obtain the CWs from the CW portion according to a second multi-level modulation format that is different from the first multi-level modulation format.

18 . The apparatus of claim 17 , wherein the first multi-level modulation format is a pulse-code modulation (PCM) format, and wherein the second multi-level modulation formation is a predetermined quadrature amplitude modulation (QAM) format.

19 . The apparatus of claim 17 , wherein the processor is further configured to demultiplex the multiplexed signal to obtain the IQ data portion and the CW portion through time-division demultiplexing (TDM).

20 . The apparatus of claim 17 , wherein the frontend is further configured to:
couple to a wireless fronthaul link; and receive the single-carrier signal via the wireless fronthaul link.

Assignees

• Futurewei Technologies Inc

Inventors

• Zeng Huaiyu
• Liu Xiang

Classifications

• H04W72/21

  in the uplink direction of a wireless link, i.e. towards the network · CPC title

• H04B10/5561

  Digital phase modulation · CPC title

• H04W88/085

  Access point devices with remote components · CPC title

• H04B10/25753 Primary

  Distribution optical network, e.g. between a base station and a plurality of remote units · CPC title

• H04B10/5053

  using a parallel, i.e. shunt, combination of modulators · CPC title