RTX41xx. Wi-Fi Module

Transcription

1 RTX41xx Wi-Fi Module Module variants covered by this document: RTX4100 RTX4140 Application note AN5 Range Performance Application note Range Performance RTX41xx Wi-Fi Module 1

2 Application note Range Performance RTX41xx Wi-Fi Module 2

3 CONTENT 1 Introduction General Description Module variants covered by this document Document History SW/HW Version Document References Test Setup Access Point and Test Environment DUT Test Application Measurement Procedure Test results Test Session Setup Test Session Results Test Tession Conclusion Test session Test Session Setup Test Session Results Test Session Conclusion Test session Test Session Setup Test Session Results Test Session Conclusion Test session Conclusions Abbreviations Liability Disclaimer Application note Range Performance RTX41xx Wi-Fi Module 3

4 1 Introduction 1.1 General Description The RTX41xx (RTX4100/RTX4140) Wi-Fi Module is a small form-factor, single stream, b/g/n Wi-Fi module with on-board low power application processor. It is targeted at applications that send infrequent data packets over the network. Typically, these applications will place a higher priority on system cost, power consumption, ease of use, and fast wake-up times as compared to high throughput. This document serves as an application note on how to perform range testing. Range is sometimes communicated as a single number indicatin the longest line of sight (LOS). The RTX41xx will rarely operate under such conditions, but more likely in difficult RF environments including reflectors like walls and floors. Reflectors can of course block the RF signal, and it will also rise several transmission paths resulting in multipath fading. Multipath fading can lead to dead spots, positions with no or bad RF link. In order to present more practical range information a real world range test have been conducted where the performance in several test positions inside an office environment is presented. The range evaluation covered in this application note is based on low power and low datarate applications such as a WiFi Tempsensor. 1.2 Module variants covered by this document All measurements documented in this document are based on RTX4100. Same performance is expected using the RTX Document History V1.0 Official release MAD V1.1 Minor corrections TM V1.2 Minor corrections MAD V1.3 Added Test Session 3 MAD V1.4 Updated references TM V1.5 Added RTX4140 TM Disclaimer: This document can be subject to change without prior notice. 1.4 SW/HW Version This document is applicable for the following versions. Terminal demo application Version and earlier Platform firmware Version and earlier WSAB version V3RA 1.5 Document References [UG1]. RTX4100_User_Guide_Module_Evaluation_UG1.pdf. [UG3]. RTX4100_User_Guide_Application_Development_UG3.pdf. [UG6]. RTX4100_User_Guide_WSAB_UG6.pdf. Application note Range Performance RTX41xx Wi-Fi Module 4

5 2 Test Setup 2.1 Access Point and Test Environment The Range Performance tests have been setup using a Linksys E1200 Access Point (AP), connected with Ethernet to a monitoring laptop. The AP is placed in the middle of a wooden table, 75cm above ground level, and 60cm away from a plaster wall. (See Figure 1). Figure 1. Linksys E1200 AP positioning As a basis for the range test, a spectrum analysis of the test environment is done using a spectrum analyser connected to an external antenna. The spectrum analysis is done to verify that the levels of disturbances from other systems in the environment. Systems not controlled in this test might give un expected and variable results when measuring range. Based on the spectrum analysis, the AP frequency band is fixed to a low activity channel to avoid as much interference as possible (see Figure 2). During the testing the AP is set to n-mode for test session 1 and 2. For test session 3 the b/g/n modes is set to auto in the AP. All tests are done with the AP in a EU region setup. Application note Range Performance RTX41xx Wi-Fi Module 5

6 Figure 2. Frequency Scan 1m away from the AP. The AP position is represented on Figure 3 with the symbol (*). The thin walls are plaster walls, while the wide walls (upper and lower walls) are concrete walls. The test facilities will be described in more details in section 3. * 2.2 DUT Test Application Figure 3. AP positioning within the building For this series of tests, a slightly modified version of the TempSensor Co-Located Application (CoLA) is used ([UG3]). The TempSensor application works the following way: The module powers on It connects to the AP It starts an UDP application Application note Range Performance RTX41xx Wi-Fi Module 6

7 It sends the temperature recorded on the WSAB in an UDP packet send to IP , port It suspends WiFi for 5 seconds It resumes WiFi It sends the new temperature recorded It suspends WiFi for 5 seconds For a detailed flow chart of the application, please refer to ([UG3]). 2.3 Measurement Procedure At each range position, a Packet Error Rate (PER) is calculated based on a minimum of 200 UDP transfers from the tempsensor application. The received packets are recorded on the laptop directly connected to the AP with a Ethernet cable. The laptop is running the UDP test tool recommended in ([UG1]), to monitor UDP packets received at the AP. The PER is calculated based on the number of packets received at the AP, compared with the amount of packets sent. The tests were run at various distances/positions in the building. 3 Test results Three testsesions are documented in the following. The AP is placed in two different positions in the building. 3.1 Test Session Setup Test Session 1 For this first series of test, the AP is placed in an office, in the central part of the builing, while measurements have been recorded in the surrounding offices and on the main corridor. The position of the AP as well as the various positions of the RTX4100 module measurements are shown on Figure 4. Application note Range Performance RTX41xx Wi-Fi Module 7

8 Concrete Walls * AP position 1 10 RTX4100 Measurements (test 1) 9 RTX4100 Measurement (test 2) * Figure 4. Measurements positions Test session 1 Application note Range Performance RTX4100 Wi-Fi Module 8

9 3.1.2 Results Test Tession 1 The test resulted in the following PER at the given positions: Measurement # Distance to AP Packet Error Rate (Packets not received) 1 1,5m 0,0% 2 9,5m 1,0% 3 10m 1,0% 4 10m 2,8% 5 11,5m 0,5% 6 20,5m 1,0% 7 24,5m 2,8% 8 30m 3,6% 9 40m 4,0% 10 56m 11,2% 12,0% 11,2% 10,0% 8,0% 6,0% PER 4,0% 2,8% 2,8% 3,6% 4,0% 2,0% 0,0% 1,0% 1,0% 1,0% 0,5% 0,0% Figure 5. Packet Error Rate - Test Conclusion Test session 1 The PER is low in the an area covering distances up to 25m. At ranges above 25m the building poses a distinct obstacle in the form of a thik concrete wall. Beyond in the offices beyond this concrete wall the RTX4100 was not able to establish link to the AP (The red zones on Figure 4 indicate the limits of connectivity). However the testpositions in the corridor showed reasonable PER rates beyond the concrete wall all the way up to the end of the building. The 2,8% PER in position #4 is higher than the PER in other positions with similar distance to the AP. This is explained by the concrete wall surrounding the staircase in this position. Application note Range Performance RTX4100 Wi-Fi Module 9

10 3.2 Test Session Setup Test Session 2 For this second series of test, the AP is placed in an office, in one of the extremities of the building. Measurements have been recorded in the surrounding offices as well as on the main corridor. The purpose of this test is to record the maximum range with the absence of the concrete wall (see test session 1). The position of the AP as well as the various positions of the RTX4100 module measurements are shown on Figure 6 (and Figure 4 for measurement #9). Note: It is important to note that RTX being a telecom company, there is a high number of wireless networks constantly powered on. This affects the test performances since packets collision are more likely to occur with a high number of AP s. For the test Session 2, twentyfour (24) AP have been recorded in the surrounding environment. Application note Range Performance RTX4100 Wi-Fi Module

11 Concrete Walls * AP position 1 9 RTX4100 Measurements 5 3 * 9 (see figure 4) Figure 6. Measurements Location Test session 2 Application note Range Performance RTX4100 Wi-Fi Module 11

12 3.2.2 Results Test Session 2 The test resulted in the following PER at the given positions: Measurement # Distance to AP Packet Error Rate (Packets not received) 1 17,5m 4,0% 2 18m 0,0% 3 20m 2,3% 4 25m 1,7% 5 27m 3,5% 6 28m 11,3% 7 31m 23,6% 8 33m 28,1% 9 (see Figure 4) 89m 9,2% 30,0% 28,1% 25,0% 23,6% 20,0% 15,0% 10,0% 11,3% 9,2% PER 5,0% 0,0% 4,0% 2,3% 1,7% 3,5% 0,0% Figure 7. Packet Error Rate - Test Conclusion Test session 2 The PER is low in the an area covering distances up to 27m. At ranges above 27m the PER rise to levels above 10%. The red zones on Figure 6 indicate the limits of connectivity which in this test is about 35m. As seen in test Session 1 the positions in the corridor showed good PER rates all the way up to the end of the building. The 4% PER in position #1 is higher than the PER in other positions with similar distance to the AP. This is explained by the concrete wall surrounding the staircase in this position. Application note Range Performance RTX4100 Wi-Fi Module 12

13 3.3 Test Session Setup Test Session 3 This third test session has been performed in another building where the number of AP was sensibly lower (10-12 vs within the RTX facilities). A central channel (8) was used with no other AP using this channel, nor the 2 adjacent channels (7 & 9). The AP was located in one of the office, in a central position relatively to the building configuration. * AP position 1 6 RTX4100 Measurements * Figure 8. Measurements Location Test session 3 Application note Range Performance RTX4100 Wi-Fi Module 13

14 3.3.2 Results Test Session 3 The test resulted in the following PER at the given positions: Measurement # Distance to AP Packet Error Rate (Packets not received) 1 16m 0,5% 2 17,5m 1,0% 3 19,5m 8,8% 4 20,5m 2,5% 5 23m 4,0% 6 25,5m 5,0% 10,0% 8,8% 8,0% 6,0% 4,0% 5,0% PER 4,0% 2,5% 2,0% 0,5% 1,0% 0,0% Figure 9. Packet Error Rate - Test Conclusion Test session 3 The PER is low in the an area covering distances up to 20m. At ranges above 20m the PER rise to levels above 4%. The red zones on Figure 8 indicate the limits of connectivity. The 8.8% PER in position #3 is higher than the PER in other positions with similar distance to the AP. This is an illustration of the sometimes unexpected results during indoor range testing, where various parameters impact on the PER. In addition to the amount of interference, the number (and structure) of walls, the distance to the AP, as well as the relative positioning of the AP s antenna to the RTX4100 module s antenna will affect the PER measurements. Application note Range Performance RTX4100 Wi-Fi Module 14

15 4 Conclusions With a low PER ratio up to 25m, in this test, the RTX4100 module is a premium choice for any indoor WiFi based application. The results obtained in this Application Note are not ment to be taken as the reference for Range performance, but rather as an indication of performance in a given indoor scenario. The RTX4100 will operate in many different and difficult RF environments including reflectors like walls and floors. Reflectors can block the RF signal, and it will also rise several transmission paths resulting in multipath fading. Multipath fading can lead to dead spots, positions with no or bad RF link. In addition to reflectors presented by the building structure such as walls structure, number of walls, also the distance and channel interferences has to be taken into account when performing range testing in any building. Based on this document, and with the use of the CoLA TempSensor, you are able to run your own measurements in the environment you are interested in. Application note Range Performance RTX4100 Wi-Fi Module 15

16 5 Abbreviations The following abbreviations are used in this document: AP API CoLA PER Wi-Fi Access Point Application Programming Interface Co-Located Application Packet Error Rate Wireless Fidelity Application note Range Performance RTX4100 Wi-Fi Module 16

17 6 Liability Disclaimer General This document and the information contained, is property of RTX A/S, Denmark. Unauthorized copying is not allowed. The information in this document is believed to be correct at the time of writing. RTX A/S reserves the right at any time to change said content, circuitry and specifications. Information contained in this document is subject to change without notice. RTX makes no warranty of any kind with regard to this material, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose. RTX shall not be liable for errors contained herein or for incidental or consequential damages in connection with the furnishings, performance, or use of this material. Warranty This product is warranted against defects in material and Workman ship for a period of one year from date of shipment. During the warranty period, RTX will at its option, either repair or replace products, which prove to be defective. For warranty service or repair, this product must be returned to a service facility designated by RTX. Buyer shall prepay shipping charges to RTX and RTX shall pay shipping charges, duties, and taxes for products returned to RTX from another country. RTX warrants that its software and firmware designated by RTX for use with a module will execute its programming instructions when properly installed on that instrument. RTX does not warrant that the operation of the product or firmware will be uninterrupted or error free. Limitation of Warranty The foregoing warranty shall not apply to defects resulting from improper or inadequate maintenance by Buyer, Buyer-supplied software or interfacing, unauthorized modification or misuse, operation outside of the environmental specifications for the product, or improper site preparation or maintenance. NO OTHER WARRANTY IS EXPRESSED OR IMPLIED. RTX SPECIFICALLY DISCLAIMS THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. Application note Range Performance RTX4100 Wi-Fi Module 17