Differential matched summed positioning

Patent metadata

Field	Value
Publication number	US-2022011394-A1
Application number	US-201917295197-A
Country	US
Kind code	A1
Filing date	Dec 13, 2019
Priority date	Dec 19, 2018
Publication date	Jan 13, 2022
Grant date	—

Abstract

A method and network node for differential matched summed antenna positioning are disclosed. According to one aspect, a method includes summing sequential uplink data signals at each of a plurality of antennas of the network node to produce a plurality of antenna signal sums. The method also includes selecting one of the antenna signal sums to be used as a reference antenna signal sum. A channel impulse response is determined for each of a plurality of other antennas by cross correlating the reference antenna signal sum with the others of the plurality of antenna signal sums. The method further includes estimating a time difference of arrival from the channel impulse responses of the plurality of antennas, and estimating an error of the estimated time difference of arrival of each antenna. A position of a wireless device is determined using the estimated time differences of arrival.

First claim

1 . A network node configured to communicate with a wireless device (WD), the network node comprising:
at least one processor; and a memory including computer readable software instructions configured to control the at least one processor to implement steps of:
summing sequential uplink data signals at each of a plurality of antennas of the network node to produce a plurality of antenna signal sums;
selecting one of the antenna signal sums to be used as a reference antenna signal sum;
determining a channel impulse response for each of a plurality of other antennas based on the reference antenna signal sum and the others of the plurality of antenna signal sums;
estimating a time difference of arrival from the channel impulse responses of the plurality of antennas;
estimating an error of the estimated time difference of arrival of each antenna; and
calculating a position of a wireless device using the estimated time differences of arrival.

2 . The network node as claimed in claim 1 , wherein determining the channel impulse response for each of the plurality of other antennas comprises cross correlating the reference antenna signal sum with the others of the plurality of antenna signal sums, and wherein from the channel impulse responses of the plurality of antennas.

3 . The network node as claimed in claim 1 , wherein determining the channel impulse response for each of the plurality of other antennas comprises multiplying, in the frequency domain, the complex conjugate of the reference antenna signal sum by each of the antenna signal sums of others of the plurality of antennas, and wherein the time difference of arrival is estimated as the time domain representation of the product of the multiplying.

4 . The network node as claimed in claim 1 , wherein the summing of sequential uplink data signals is calculated as the sum of orthogonal frequency division multiplex, OFDM, symbols received at an antenna.

5 . The network node as claimed in claim 1 , wherein a reference antenna is selected from the plurality of antennas as the antenna having a signal to noise ratio, SNR, of at least 10 dB.

6 . The network node as claimed in claim 1 , wherein a plurality of channel impulse responses are calculated from a subset of symbols and summing is performed on channel impulse responses.

7 . The network node as claimed in claim 6 , wherein the calculated channel impulse response is bounded in a time domain by a channel impulse response of a demodulation reference signal, DMRS, symbol from at least one of the plurality of antenna signals.

8 . The network node as claimed in claim 1 , wherein a time-based linear quadratic estimation algorithm is employed to minimize statistical noise on the time difference of arrival calculations.

9 . The network node as claimed in claim 6 , wherein the channel impulse response is calculated as a plurality of antenna signal sums of reference symbols cross correlated with a reference antenna sum of reference symbols.

10 . The network node as claimed in claim 1 , wherein the estimation of time differences of arrival are based on knowledge that orthogonal frequency division multiplex, OFDM, symbol timing is free of jitter.

11 . The network node as claimed in claim 1 , wherein the antenna signal sums are integrated over a duration of one of 50 ms, 500 ms and 5000 ms.

12 . The network node as claimed in claim 1 , wherein the network node is configured to use Uplink Resource Allocation Type 0 to have a minimum uplink grant window size of 16 resource blocks and is configured to grant at least two uplink grant windows to a wireless device to ensure that an uplink signal bandwidth is at least 32 resource blocks wide regardless of wireless device buffer status report indications.

13 . The network node as claimed in claim 1 , wherein the network node is configured to use Uplink Resource Allocation Type 1, with no minimum uplink grant window size and is configured to grant a virtual resource block of at least 32 resource blocks to a wireless device regardless of wireless device buffer status report indications.

14 . The network node as claimed in claim 1 , wherein the network node is configured to issue frequent periodic or aperiodic uplink grants of greater than 16 resource blocks regardless of wireless device buffer status report indications.

15 . A method implemented in a network node, the method comprising:
summing sequential uplink data signals at each of a plurality of antennas of the network node to produce a plurality of antenna signal sums; selecting one of the antenna signal sums to be used as a reference antenna signal sum; determining a channel impulse response for each of a plurality of other antennas based on the reference antenna signal sum and the others of the plurality of antenna signal sums; estimating a time difference of arrival from the channel impulse responses of the plurality of antennas; estimating an error of the estimated time difference of arrival of each antenna; and calculating a position of a wireless device using the estimated time differences of arrival.

16 . The method of claim 15 , wherein determining the channel impulse response for each of the plurality of other antennas comprises cross correlating the reference antenna signal sum with the others of the plurality of antenna signal sums, and wherein from the channel impulse responses of the plurality of antennas.

17 . The method of claim 15 , wherein determining the channel impulse response for each of the plurality of other antennas comprises multiplying, in the frequency domain, the complex conjugate of the reference antenna signal sum by each of the antenna signal sums of others of the plurality of antennas, and wherein the time difference of arrival is estimated as the time domain representation of the product of the multiplying.

18 . The method as claimed in claim 15 , wherein the summing of sequential uplink data signals is calculated as the sum of orthogonal frequency division multiplex, OFDM, symbols received at an antenna.

19 . The method as claimed in claim 15 , wherein a reference antenna is selected from the plurality of antennas as the antenna having a signal to noise ratio, SNR, of at least 10 dB.

20 . The method as claimed in claim 15 , wherein a plurality of channel impulse responses are calculated from a subset of symbols and summing is performed on channel impulse responses.

21 . The method as claimed in claim 20 , wherein the calculated channel impulse response is bounded in a time domain by a channel impulse response of a demodulation reference signal, DMRS, symbol from at least one of the plurality of antenna signals.

22 . The method as claimed in claim 15 , wherein a time-based linear quadratic estimation algorithm is employed to minimize statistical noise on the time difference of arrival calculations.

23 . The method as claimed in claim 20 , wherein a channel impulse response is calculated as a plurality of antenna signal sums of reference symbols cross correlated with a reference antenna sum of reference symbols.

24 . The method as claimed in claim 15 , wherein the estimation of time differences of arrival are based on knowledge that orthogonal frequency division multiplex, OFDM, symbol timing is free of jitter.

25 . The method as claimed in claim 15 , wherein the antenna signal sums are integrated over a duration of one of 50 ms, 500 ms and 5000 ms.

Assignees

• Ericsson Telefon Ab L M

Inventors

• Smith Roland
• Berg Miguel
• Dwivedi Satyam
• Skof Mike

Classifications

• H04L25/0204

  of multiple channels · CPC title

• G01S5/06

  Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements (G01S5/12 takes precedence) · CPC title

• H04L5/0051

  of dedicated pilots, i.e. pilots destined for a single user or terminal · CPC title

• G01S5/0218 Primary

  Multipath in signal reception · CPC title

• G01S2205/01

  specially adapted for specific applications · CPC title