Version 21.4 by Xiaoling on 2023/04/14 11:04
Show last authors
1 **Table of Contents:**
2
3 {{toc/}}
4
5
6
7
8
9 = 1.  OverView =
10
11
12 In real-world deployment for LoRa, distance is a common topic. We always want to have the longest distance. This chapter shows some instructions for how to improve this.
13
14
15 = 2.  Analyze at the software side =
16
17 == 2.1  LoRa parameters that effect distance ==
18
19
20 Some settings in End Node will affect the transfer distance. They are:
21
22 * (% style="color:blue" %)**TXPower: **(%%)This means the output power from End Node. There is a command [[AT+TXP>>url:http://wiki.dragino.com/xwiki/bin/view/Main/End%20Device%20AT%20Commands%20and%20Downlink%20Command/#H7.14TransmitPower]] can be used to set the output power. TXP parameters follow the LoRaWAN regional document (rp2-1.0.3-lorawan-regional-parameters.pdf). Set to (% style="color:#037691" %)**AT+TXP=0**(%%) is always has the maximum output, but (% style="color:#037691" %)**AT+TXP=0**(%%) has different value in different frequency bands.
23
24 * (% style="color:blue" %)**Data Rate(DR): **(%%)This is a combination of Spreading Factor and Band Width. Lowest Data Rate (DR=0) always has the longest transmit distance in LoRaWAN protocol.
25
26 Below is the TXPower and DR table of EU868 Frequency band as reference.
27
28
29 [[image:image-20221006185826-1.png]]
30
31
32 [[image:image-20221006185826-2.png]]
33
34
35 Set (% style="color:#037691" %)**AT+TXP=0**(%%) **and** (% style="color:#037691" %)**AT+DR=0**(%%) will always has the longest transmit distance. But note that different frequency band has different TXP and DR coding according to LoRaWAN regional settings. Below is example for EU868, US915 and AS923 compare for example.
36
37
38 **End node actually value when TXP=0 and DR=0**
39
40 (% border="1.5" cellspacing="4" style="background-color:#f2f2f2; width:1002px" %)
41 |(% style="background-color:#d9e2f3; width:134px" %)**Frequency band**|(% style="background-color:#d9e2f3; width:400px" %)**Output Power in LoRa Module (consider 2dB antenna)**|(% style="background-color:#d9e2f3; width:362px" %)(((
42 **Spreading Factor(Higher SF can transmit further)**
43 )))|(% style="background-color:#d9e2f3; width:102px" %)**Band Width**
44 |(% style="width:134px" %)**EU868**|(% style="width:400px" %)14dBm|(% style="width:362px" %)SF=12|(% style="width:102px" %)125Khz
45 |(% style="width:134px" %)**US915**|(% style="width:400px" %)20 or 22 dBm (depends on max output of module)|(% style="width:362px" %)SF=10|(% style="width:102px" %)125Khz
46 |(% style="width:134px" %)**AS923**|(% style="width:400px" %)14dBm|(% style="width:362px" %)SF=12|(% style="width:102px" %)125Khz
47
48
49
50 == 2.2  Adaptive Data Rate (ADR) and set max distance ==
51
52
53 (% style="color:#037691" %)**ADR**(%%) is the feature that Server will ask End Node to adjust the TXP and DR according to some rules in the server. This is for the purpose of Network Management and Optimize End Node battery life-time.
54
55
56 By default, ADR is turn on((% style="color:#037691" %)**AT+ADR=1**) (%%)so End node ADR feature is enable.
57
58
59 (% style="color:blue" %)**Normally, user can set the max distance by setting:**
60
61 (% style="color:#037691" %)**AT+ADR=0**
62
63 (% style="color:#037691" %)**AT+DR=0  **~/~/(%%) Use longest distance modulation
64
65 (% style="color:#037691" %)**AT+TXP=0   **(%%)~/~/ Use max power   For EU868, max power can be is AT+TXP=50
66
67
68 This can be downlink via the LoRaWAN downlink command, see [[this link>>url:http://wiki.dragino.com/xwiki/bin/view/Main/End%20Device%20AT%20Commands%20and%20Downlink%20Command/#H8.2UseDownlinkCommandtosetafixuplinkDR]] for reference.
69
70
71 == 2.3  Check for short distance problem ==
72
73
74 According to the above technology, if we have a problem on the distance, we can first check if the end node is trying to longest distance modulation already. We can see that from the LoRaWAN server. Below is an example from Chirpstack.
75
76
77 We can see the traffic in gateway's page and know that the distance is SF12 / BW125. (note, server is not able to know Transmit Power settings from End Node)
78
79
80 [[image:image-20221006185826-3.png]]
81
82
83 == 2.4  Best software settings for the longest distance ==
84
85
86 Below are the settings for longest distance transmission. ( will reduce battery life)
87
88 * (% style="color:#037691" %)**AT+ADR=0**  (%%)~/~/  Disable ADR
89 * (% style="color:#037691" %)**AT+DR=  0**  (%%)~/~/  Use the smallest DR,the longest distance modulation
90 * (% style="color:#037691" %)**AT+TXP=0**    (%%) ~/~/  Use max power   For EU868, max power can be is AT+TXP=50
91
92
93
94 = 3.  Analyze at the hardware side =
95
96 == 3.1  Check if the antenna path is good ~-~- For LSn50v2 series end node ==
97
98
99 a) Open Enclosure and Check if the antenna connection to module is good.
100
101 b) check if the connector match.
102
103
104 [[image:image-20221016081725-1.png||height="426" width="706"]]
105
106
107 = 4.  Installation Guidelines =
108
109 == 4.1  Check the use environment ==
110
111
112 First , User should notice: Radio link quality and performances are highly dependent of the environment.Even you have the same hardware and antenna, Different installation will result in different performance.
113
114 (% style="color:blue" %)**Better performances can be reached with:**
115
116 * Outdoor environment.
117 * No obstacles.
118 * No high level radio interferes in the ISM band you use.
119 * At least 1 meter above the ground.
120
121 (% style="color:blue" %)**Radio performances are degraded with:**
122
123 * Obstacles: buildings, trees...
124 * Inner buildings environments.
125 * High ISM band usage by other technologies.
126 * Radio communication are usually killed with bad topographic conditions. It is usually not possible to communicate through a hill, even very small.
127
128
129
130 == 4.2  Improve the Antenna ==
131
132
133 In some case, we have to install the device inside the chamber or next to a metal case. So the signal between the antenna and the receiver (gateway) is blocked by the metal. This will greatly reduce the signal. In such case, we can consider using antenna extend cable to extend the antenna to a better position.
134
135
136 = 5.  Some real-world case =
137
138 == 5.1  Server reason cause end node has problem on Join. ==
139
140
141 In one case, the customer is using AWS IoT Core and gateway to connect to AWS via Basic Station Connection, Frequency Band is AU915 sub-band 2. For some unknown reason, AWS always set downlink power to 0dBm, which cause the gateway only emit a very low power and lead to a short distance for sensor.
142
143
144 Below is the output log in gateway side ( SSH Access to Gateway and Check Station log)
145
146
147 [[image:image-20221006185826-4.png]]
148
149
150 The fix of this issue is to set the output power to a high value even server ask to send out 0dBm.
151
152 Reference Link:  [[http:~~/~~/wiki.dragino.com/xwiki/bin/view/Main/Change%20Gateway%20Power/#H1.A0Overview>>http://wiki.dragino.com/xwiki/bin/view/Main/Change%20Gateway%20Power/#H1.A0Overview]]
153
154
155 == 5.2 Chirpstack Default settings to 64 channels which cause Signal Poor. ==
156
157
158 In this case, User use a Chirpstack LoRaWAN server with default settings. The Frequency Band is US915 and default settings of Chirpstack has all channels ( All sub-bands , total 72 channels) enable. User use a LDS03A and a LPS8N LoRaWAN gateway for the test.
159
160
161 There is a strange issue: LDS03 has a very good RSSI ( RSSI=-40) during OTAA Join. But The LDS03A give a very poor RSSI after OTAA Join. After debug, it proves that the issue is with ChirpStack Frequency band settings. The ChirpStack server enables all 72 channels and the LDS03A will also use all channels after OTAA Join, but the LPS8N only can support 8 channels and set to Sub-Band2. When the LDS03A sends an uplink packet in the channel LPS8N doesn't support, because LDS03A is very close to LPS8N, LPS8N pick up this not support frequency and send to server. So in the platform we see a uplink packet with very poor RSSI.
162
163
164 Above issue was confirmed and solved after set the ChirpStack support channels to sub-band2. See below for photos during debug.
165
166 [[image:image-20221031233628-2.png]]
167
168
169 [[image:image-20221031233759-3.png]]
170
171
172 [[image:image-20221101000006-1.png||height="353" width="931"]]
173
174
175 = 6. Use a repeater =
176
177
178 In some cases, user can consider use a repeater for limitation transmition.
179
180 See here for how to set up: [[http:~~/~~/wiki.dragino.com/xwiki/bin/view/Main/User%20Manual%20for%20All%20Gateway%20models/LoRaWAN%20IoT%20Kit%20v3%20User%20Manual/#H7.Example6:LimitedLoRaWANrelay >>http://wiki.dragino.com/xwiki/bin/view/Main/User%20Manual%20for%20All%20Gateway%20models/LoRaWAN%20IoT%20Kit%20v3%20User%20Manual/#H7.Example6:LimitedLoRaWANrelay]]
181
182

Applications

Navigation

Copyright ©2010-2022 Dragino Technology Co., LTD. All rights reserved
Dragino Wiki v2.0