METHOD FOR SIMULTANEOUS CONFIRMATION OF MANY MESSAGES IN LOW POWER WIDE AREA NETWORKS, AND USE OF CORRECTION OF FREQUENCY WHEN TRANSMITTING DATA OVER UNB LPWAN NETWORKS, BASED ON ANALYSIS OF DATA OBTAINED ON RECEIVING

Abstract

Described is a method for joint confirmation of many messages in Low Power Wide Area Networks (LPWANs) including adding information on order of messages in transmitted data, parsing order data in messages on a receiving side, sending system message back to original transmitter where information on reception success is encoded bitwise in data field, so that each bit represents one successfully received message.

Claims

1. A method of simultaneous confirmation of messages, comprising: matching frequencies of a transmitter and a receiver by processing a wide frequency band for narrowband signals transmitted from an end device to a base station; matching a frequency of signal and a frequency of tuning of input filters by a way of an algorithm used to compensate instability of frequencies of master oscillators for narrowband signals transmitted from the base station;

2. The method according to claim 1 wherein a real frequency of signal is measured with a certain error, and a difference between actual and expected signal frequencies includes: i)
f.sub.1=f.sub.exp.sub._.sub.ulf.sub.rx, where f.sub.1 includes both an error of a transmitter of a remote modem, and an error of measuring a frequency of the base station includes:
f.sub.1=f.sub.ul+f.sub.bs, and ii) these errors have sufficiently stable values caused by initial inaccuracy of generators, and use of thermally stabilized oscillators (TCXO) do not change significantly with temperature fluctuations;

3. The method according to claim 1 wherein a base station transmitter sends signal at a fixed frequency f.sub.exp.sub._.sub.dl with a certain periodicity, and the second frequency error of signal received by the same base station includes: i)
f.sub.2=f.sub.exp.sub._.sub.dlf.sub.rx, and ii) an error includes both an error of the transmitter of the base station, and an error of measuring a frequency of the base station includes:
f.sub.2=f.sub.di+f.sub.bs;

4. The method according to claim 1 wherein the base station compensates a frequency error of a receiver for signal sent from an end device to the base station, and a frequency of signal includes: i)
f.sub.tx=f.sub.exp.sub._.sub.dl+f.sub.1f.sub.2+f.sub.dl*=f.sub.exp.sub._.sub.dl+f.sub.ul, where *f.sub.dl is added by the base station transmitter, and ii) f.sub.exp.sub._.sub.dl+f.sub.ul corresponds exactly to an actual frequency of a remote modem receiver and includes its error; iii) calculations are valid wherein an error in a frequency of the modem is equal to both during reception and transmission under the condition that f.sub.exp.sub._.sub.ulf.sub.exp.sub._.sub.dl; otherwise, compensation of the frequency error includes:
f.sub.tx=f.sub.exp.sub._.sub.dl+f.sub.exp.sub._.sub.dl/f.sub.exp.sub._.sub.ul.Math.(f.sub.1f.sub.2);

5. The method according to claim 1 wherein detection and reception of data are performed in a wider frequency range sufficient to compensate an error in oscillators.

Description

DETAILED DESCRIPTION

[0005] The exemplary embodiment maybe further understood with reference to the following description. The exemplary embodiment of present invention provides a confirmation of many data messages with just one message thereby saving power. The described embodiment implies ability to measure accurately at frequency of received signals at input of base station.

[0006] When narrowband radio signals (UNB) are used in LPWAN networks with signal bandwidth of 500 Hz or less, inaccurate frequency shaping by master oscillators can lead to problems associated with mismatch between transmitter and receiver frequencies, which causes packet loss. For UNB signals transmitted from an end device to a base station (uplink), this problem can be solved by processing a wide frequency band. In a reverse direction (downlink), reception of signals, as a rule, is carried out by means of serial radiotransivers, which process only a narrow band of signal. In this case, to successfully receive a signal, it is necessary to accurately match a frequency of signal and a frequency of tuning of input filters of radio transceiver. For example, for signals with a bandwidth of 200 Hz, accuracy of coincidence of frequencies should be of order of several tens of Hertz. To solve this problem, an algorithm can be used to compensate instability of frequencies of master oscillators, essence of which is described below.

[0007] Packets are transmitted in both directions at frequencies that are uniquely determined by data contained in a packet. When the packet is received, a real frequency of signal is measured with a certain error and a difference, i.e., an error, between actual and expected signal frequencies is calculated:

f.sub.1=f.sub.exp.sub._.sub.ulf.sub.rx

[0008] Composition of this error includes both an error of a transmitter of a remote modem and an error of measuring a frequency of a base station:

f.sub.1=f.sub.ul+f.sub.bs

[0009] These errors have sufficiently stable values caused by initial inaccuracy of generators, and use of thermally stabilized oscillators (TCXO) do not change significantly with temperature fluctuations.

[0010] A base station transmitter, used to send downlink packets, also, with a certain periodicity (every 5 minutes), sends uplink packets at a fixed frequency f.sub.exp.sub._.sub.dl. These packets are received by the same base station, and the second frequency error is calculated by using the following formula:

f.sub.2=f.sub.exp.sub._.sub.dlf.sub.rx

[0011] Composition of this error includes both an error of the transmitter of the base station and an error of measuring a frequency of the base station:

f.sub.2=f.sub.dl+f.sub.bs

[0012] When sending a downlink packet, the base station compensates a frequency error of a receiver in a modem of a destination device, sending a packet at the following frequency:

f.sub.tx=f.sub.exp.sub._.sub.dl+f.sub.1f.sub.2+f.sub.dl*=f.sub.exp.sub._.sub.dl+f.sub.ul

[0013] *f.sub.dl is added by the base station transmitter.

[0014] f.sub.exp.sub._.sub.dl+f.sub.ul corresponds exactly to an actual frequency of the remote modem receiver and includes its error.

[0015] These calculations are valid in case when an error in a frequency of the modem is equal to both during reception and transmission. This is true under the following condition:

f.sub.exp.sub._.sub.ulf.sub.exp.sub._.sub.dl

[0016] Otherwise, a formula for compensation of frequency errors as follows:

f.sub.tx=f.sub.exp.sub._.sub.dl+f.sub.exp.sub._.sub.dl/f.sub.exp.sub._.sub.ul.Math.(f.sub.1f.sub.2)

[0017] A similar result can be achieved by implementing a receiving part of the radio modem of a final device in such a way that detection and reception of data would be performed in a wider frequency range sufficient to compensate for errors in the reference oscillators. This solution involves abandonment of existing on market serial radio transceivers and implementation or application of receiver with more expensive components with higher power consumption.