Open Source Wireless Transmission Line Analysis (OSWTLA) Step towards Preparing Wi-Fi Signal Map Mobile App of HITAM

2015

Azeem Unnisa, Assistant Professor Department of ECE, HITAM

Abstract

This Project Open Source Wireless Transmission Line Analysis (OSWTLA) is

an innovation made in short duration of three days with inspiration from

Dr.Vinod Lohanis project LEWAS lab. As we dont have resources to set up

such kind of lab which is a learning resource for 1800 student at Virginia Tech,

I and my student Ayush Kumar Dwivedi came up with the idea of creating a

learning resource with available resources that is OSWTLA. OSWTLA is a

technology enabled learning resource which can aid students to learn the

concept transmission line of my course, Electromagnetic theory and

Transmission Line (EMTL). The popularity of laptops, mobile devices among

people leads to the needs for good quality of Wi-Fi in public places. In planning

field, serving public is one of our research goals. This study was thought out in

order to approach the goal. We first discussed the necessity of making a map

showing Wi-Fi signal strength mobile App. We also studied two existing

examples, they tried to map Wi-Fi signal by different ways. As a beginning of

the mapping process, a small study was conducted measuring the signal

strength at various distances from the router. Aim of the project taken up id to

develop such mobile App which shows the map of Wi-Fi strength for whole

HITAM campus which would facilitate the users to select the best location for

using the Wi-Fi service, which in turn provides hundreds of student a platform

to link technology with their learning and also create such kind of learning

environment. In this project LABVIEW software is also used to analyze the

data obtained from the observation at Campus by simulating the data.

Keywords: OSWTLA, EMTL, Wi-Fi, LABVIEW, LEWAS Lab.

Introduction

The increasing of mobile device, such as iPad, Samsung Tablet, and Google Chrome

Laptop, has promoted the application of Wi-Fi technology. Wi-Fi has become very

popular in public places such as parks, campus, airports, coffee shop and restaurant

now. Providing free Wi-Fi can attract more guests and preserve their visiting in business.

This is very obvious when we walk into a free Wi-Fi coffee shop or restaurant. While

providing free Wi-Fi seems a good way for enhance more sales in businesses, but based

on our research, promoting visiting by providing free Wi-Fi sometimes is not a good

idea, when too many people get crowd in coffee shop. That is because water body will

obstruct the signal. While people may get crowd in coffee shops, bars, or restaurants

easily, but in our campus, people only get crowd in classrooms and sometimes get

crowd in an open space occasionally. Currently, Wi-Fi signal has covered most buildings

and areas in our campus. But outside the buildings the Wi-Fi signal in some places

turned to unstable sometimes. During the time when there is a big activity hold in

campus, such as go big red, visitors get crowd in campus and the needs for Wi-Fi

rising, but the signal actually dropping. In addition, based on my daily experience in our

campus, there is also a strong need among students and faculties for covering the open

space by good quality of Wi-Fi signals in our campus. When the weather is nice, some

people prefer to use their laptops outside the building. It is helpful to consider the Wi-Fi

factors when we try to change an inactivated open space into a successful open space in

the planning fields. And mapping the Wi-Fi signal not only can provide convenience for

faculties, students, and visitors, but also can provide helpful information for the network

administrators to make better investment decisions for Wi-Fi antenna placement on the

Campus. It is necessary for us to have a map showing the Wi-Fi signal strength in our

campus.

Details of the Router Analyzed

DIR-605L WIRELESS N300 D LINK CLOUD ROUTER

DIR-605L is designed to support Android/iPhone App mydlink lite and capable of

providing push event, user control and real-time browsing record via mydlink cloud

service. This allows home user to monitor/control the network clients via Android

Phone or iPhone Application. You can also check the visited website record of

network clients while they are doing the net-surfing. If any wireless intruder

intends to break into your home network will trigger push messages to your

cellphone and let you choose block or not. It complied with IEEE802.11b/g/n 2x2

MIMO WLAN technology, transmit data rate up to 300 Mbps.

SPECIFICATIONS

Standards IEEE 802.11n up to 300 Mbps IEEE 802.11g

IEEE 802.11b

IEEE 802.3 IEEE 802.3u

SSID hitam.org

Wireless Frequency Range 2.4 Ghz to 2.4835 Ghz

Antennas Fixed 5 dbi External Antennas

Security Wi-Fi Protected Access

WPS (PBC/PIN)

Advanced Features mydlink app for iOS and Android

Push Notifications: Wireless Intrusion Online User Notice

New firmware upgrade User Control

Access Control Real time browsibg records

WDS, WDS + AP IPMAC binding, Traffic Control UPnP Support

Advance Firewall Features Network Address Translation (NAT )

Stateful Packet Inspection (SPI)

MAC Address Filtering

URL Filtering

Device Management Web UI

Certifications NCC/FCC

CE CCC

Wi-Fi Protected System(WPS)

Wi-Fi Certified

Observations

S.NO. Distance from Router (M)

Signal Strength (dBm)

Arbitrary Strength Unit (ASU)

01 0 0 55

02 0.10 -26 43

03 0.20 -34 39

04 0.30 -36 38

05 1 -43 35

06 3 -45 34

07 4 -55 29

08 5 -60 28

09 12 -74 19

10 15 -78 17

11 22 -80 15

12 30 -83 13

13 40 -87 12

14 50 -90 10

Technical Aspects

What does dBm in Signal Strength signifies? dBm (sometimes dBmW or Decibel-milliwatts) is an abbreviation for the power

ratio in decibels (dB) of the measured power referenced to one miliwatt(mW). It

is used in radio, microwave and fiber optic networks as a convenient measure of

absolute power because of its capability to express both very large and very small

values in a short form. Compare dBW, which is referenced to one watt

(1000 mW).Since it is referenced to the watt, it is an absolute unit, used when

measuring absolute power. By comparison, the decibel (dB) is a dimensionless

unit, used for quantifying the ratio between two values, such as signal-to-noise

ratio.

What does negativedBm in Signal Strength signifies? Absolute power of a signal is measured in wattage. The bel or decibel system can

only describe relative power- a gain of 3 dB means your signal is 2 times as strong

as it was before, but the dB scale doesn't define where you're starting from or

what your 'zero' is. So, we specify dBm, indicating that our scale is relative to 1

milliWatt of power.

0 dBm = 1 mW

The reason we see negative values is that you're representing small but positive

numbers, on a logarithmic scale. In logarithms, the value indicated represents an

exponent. For example, under a log 10 scale, a value of -2 represents 10 -2, this

equals 0.01. Likewise, a negative dBm means that you're applying a negative

exponent in your power calculation,; 0 dBm equals 1 mW of power, so -10 dBm

equates to 0.1 mW, -20 dBm equates to 0.01 mW, and so forth. It's a lot easier,

and more useful in some calculations, to describe a weak signal as -100 dBm as

opposed to 0.0000000001 mW.

What doesArbitrary Strength Unit (ASU)mean? Arbitrary Strength Unit (ASU) is an integer value proportional to the received

signal strength measured by the mobile phone. It is possible to calculate the real

signal strength measured in dBm (and thereby power in Watts) by a formula.

However, there are different formulas for 2G and 3G networks. In GSM networks,

ASU maps to RSSI.

dBm = 2 ASU - 113, ASU in the range of 0..31 and 99 (for not not detectable)

Observation Plot: Distance vs Signal Strength

Observation Plot: Distance vs Arbitrary Strength Unit(ASU)

Plots of strength for specific distances

Few of the plots obtained for specific distances ate attached for the reader reference.

1. Distance from Router: 0 m

2. Distance from Router: 3 M

3. Distance from Router: 12 M

4. Distance from Router: 40 M

Plot Representing Gradual Decrease in Signal Strength as Distance

Increases

GUI of Android App Used for Collecting Data

Conclusion and Future Scope

As engineers, our research goal is serving the public. While during our research we

discovered among public, there is a need that people want to know where the best

place might be for them using their laptops, smart devices in our campus. And it is very

obviously that existing Wi-Fi signal map cannot meet this need. It is necessary for us to

produce a detailed and reliable Wi-Fi signal map mobile application for the public in our

campus. In order to produce a good quality Wi-Fi signal map, mapping Wi-Fi signal

strength precisely has become our primary task. It needs a huge and longtime data

collection work, but it is still possible to produce a precise Wi-Fi signal strength map in

our campus. By using different platforms or devices, we can collect the data gradually,

but we must be sure that the environmental factors are minimized to the smallest

before we get started. And if we can choose several most popular platforms or devices

as our measurement tools, the results also will be more reliable to the public.

Future Scope:

To obtain a Wi-Fi signal map for complete HITAM campus and predict the

possible location in the campus for installing signal boosters for better signal

strength.

Study of the effect on buildings structure and materials used within the access

points set up at different locations and obtaining Wi-Fi measurements and

comparing them with values predicted by classical model such as ITU Indoor

Propagation Model.

Study the conduct of signal strength when it travels through line of sight (LoS)

and non-line of sight (NLoS) and results will be compared with an Indoor site

general model of ITU.

Calculate the free space path loss and loss due to other materialistic objects in

dB.