Hybrid quantize-forward and decode-forward relaying transmission for massive MIMO HetNets

Patent metadata

Field	Value
Publication number	US-12004069-B2
Application number	US-201917614727-A
Country	US
Kind code	B2
Filing date	Jun 19, 2019
Priority date	Jun 19, 2019
Publication date	Jun 4, 2024
Grant date	Jun 4, 2024

Abstract

A method, network node and processor for processing uplink signals transmitted from a wireless device (WD) to provide a combination of quantize-forwarding and decode-forwarding relayed signals in massive multiple input multiple output (MIMO) heterogeneous networks (HetNets). According to one aspect, whether quantize-forwarding or decode-forwarding is used depends on a ratio of a quality of a WD signal received at a Small Cell Base Station (SCBS) to a quality of the WD signal received at a Macro Cell Base Station (MCBS). When the ratio is less than a first threshold, signals received at the SCBS may be quantize-forwarded to the MCBS and when the ratio exceeds a second threshold larger than the first threshold, signals received at the SCBS may be decode-forwarded to the MCBS. When the ratio lies between the first and second threshold, signals received at the SCBS may be quantize-forwarded to the MCB.

First claim

What is claimed is:

1. A method for processing uplink signals transmitted from a wireless device, WD, to a small cell base station, SCBS, and from the SCBS to a macro cell base station, MCBS, the MCBS serving a macro cell that at least partially includes a small cell served by the SCBS, the method comprising:
for each of a plurality of WDs served by the SCBS:
determining a ratio of signal quality of a signal received from the WD at the SCBS to a signal quality of a signal received from the WD at the MCBS;
comparing the determined ratio to a first threshold; and
when the ratio is less than the first threshold, forwarding the signal received at the SCBS to the MCBS as a quantize-forward, QF, relay signal;
when the determined ratio is greater than the first threshold, comparing the determined ratio to a second threshold greater than the first threshold, and if the determined ratio is greater than the second threshold, forwarding the signal received at the SCBS to the MCBS as a decode-forward, DF, relay signal; and
otherwise, forwarding the signal received at the SCBS to the MCBS as a QF relay signal.

2. The method of claim 1 , wherein the second threshold is determined based at least in part on a linear threshold search of no more than K iterations, where K is the number of the plurality of WDs served by the SCBS.

3. The method of claim 1 , wherein the second threshold is determined such that a number of WDs selected for DF relaying results in a maximum weighted sum rate of signals relayed from the SCBS to the MCBS.

4. The method of claim 1 , further comprising determining a quantization for each WD signal forwarded by QF relaying, the quantization being determined by a water-filling algorithm.

5. The method of claim 4 , further comprising determining a phase duration for each forwarded WD signal, the phase duration being determined by the water-filling algorithm.

6. The method of claim 4 , wherein the water-filling algorithm includes:
prioritizing the WDs based at least in part on weighting factors and on the determined ratio for each WD;
determining a maximum transmit rate for each WD in order of priority; and
determining phases of the WDs as a function of their maximum transmit rates.

7. The method of claim 1 , wherein the forwarding is by a transmission process that includes binning the WD signals and transmitting binning indices that at least one of:
include quantization indices of QF relay signals; and
that correspond to decoded messages of the DF relay signals.

8. The method of claim 7 , wherein the transmission process includes applying separate sequential sliding window decoding over two sequential transmission blocks received at the MCBS.

9. The method of claim 8 , wherein the decoding at the MCBS includes decoding a signal from an nth WD sent in a first of the two transmission blocks by applying zero-forcing detection to separate data streams of the WDs and data streams of the SCBS.

10. The method of claim 8 , wherein the decoding at the MCBS further includes decoding a bin index of the nth WD signal in the second transmission block using an nth phase and further decoding a message of the nth WD signal based at least in part on the bin index.

11. A network node for processing uplink signals from a wireless device, WD, to a small cell base station, SCBS, and from the SCBS to a macro cell base station, MCBS, the MCBS serving a macro cell that at least partially includes a small cell served by the SCBS, the network node including processing circuitry configured to:
for each of a plurality of WDs served by the SCBS:
determine a ratio of signal quality of a signal received from the WD at the SCBS to signal quality of a signal received from the WD at the MCBS;
compare the determined ratio to a first threshold; and
when the ratio is less than the first threshold, forward the signal received at the SCBS to the MCBS as a quantize-forward, QF, relay signal;
when the ratio is greater than the first threshold, compare the determined ratio to a second threshold greater than the first threshold and if the determined ratio is greater than the second threshold, forward the signal received at the SCBS to the MCBS as a decode-forward, DF, relay signal; and
otherwise, forward the signal received at the SCBS to the MCBS as a QF relay signal.

12. The network node of claim 11 , wherein the second threshold is determined based at least in part on a linear threshold search of no more than K iterations, where K is the number of the plurality of WDs served by the SCBS.

13. The network node of claim 11 , wherein the second threshold is determined such that a number of WDs selected for DF relaying results in a maximum weighted sum rate of signals relayed from the SCBS to the MCBS.

14. The network node of claim 11 , wherein the processing circuitry is further configured to determine a quantization for each WD signal forwarded by QF relaying, the quantization being determined by a water-filling algorithm.

15. The network node of claim 14 , wherein the processing circuitry is further configured to determine a phase duration for each forwarded WD signal, the phase duration being determined by the water-filling algorithm.

16. The network node of claim 14 , wherein the water-filling algorithm includes:
prioritizing the WDs based at least in part on weighting factors and on the determined ratio for each WD;
determining a maximum transmit rate for each WD in order of priority; and
determining phases of the WDs as a function of their maximum transmit rates.

17. The network node of claim 11 , wherein the forwarding is by a transmission scheme that includes binning the WD signals and transmitting binning indices that at least one of:
include quantization indices of QF relay signals; and
that correspond to decoded messages of the DF relay signals.

18. The network node of claim 17 , wherein the transmission scheme includes applying separate sequential sliding window decoding over two sequential transmission blocks at the MCBS.

19. The network node of claim 18 , wherein the decoding at the MCBS includes decoding a signal from an nth WD sent in a first of the two transmission blocks by applying zero-forcing detection to separate data streams of the WDs and data streams of the SCBS.

20. The network node of claim 18 , wherein the decoding at the MCBS further includes decoding a bin index of the nth WD signal in the second transmission block using an nth phase and further decoding a message of the nth WD signal based at least in part on the bin index.

21. A processor for processing uplink signals from a wireless device, WD, to a small cell base station, SCBS, and from the SCBS to a macro cell base station, MCBS, the MCBS serving a macro cell that at least partially includes a small cell served by the SCBS, the processor comprising:
a ratio determiner configured to receive or determine a ratio of a signal quality of a signal received from the WD at the SCBS to a signal quality of a signal received from the WD at the MCBS;
a first comparator configured to compare the ratio to a first threshold;
a second comparator configured to compare the ratio to a second threshold; and
a signal forwarder configured to forward the signal received at the SCBS to the MCBS as a quantize-forward, QF, relay signal when the ratio is less than the first threshold, as a QF relay signal when the ratio is greater than the first threshold but less than the second threshold, and as a decode-forward, DF, relay signal when the ratio

Assignees

• Ericsson Telefon Ab L M

Inventors

• Boudreau Gary
• Abu Al Haija Ahmad
• Dong Min
• Liang Ben

Classifications

• H04W40/22 Primary

  using selective relaying for reaching a BTS [Base Transceiver Station] or an access point · CPC title

• H04B7/0413 Primary

  MIMO systems · CPC title

• H04B7/15557

  Selecting relay station operation mode, e.g. between amplify and forward mode, decode and forward mode or FDD - and TDD mode · CPC title

• H04B7/15542

  Selecting at relay station its transmit and receive resources (selection of wireless resources by user or terminal H04W72/02; arrangements affording multiple use of the transmission path by two-dimensional division of the resources H04L5/0003, or by allocating sub-channels H04L5/003) · CPC title

• H04B7/022

  Site diversity; Macro-diversity (using two or more spaced independent antennas H04B7/04) · CPC title