Wireless Communication Protocols by Mike Denko Alex Motalleb

Wireless Communication Protocols by Mike Denko, Alex Motalleb, and Tony Qian Image taken from: http: //findicons. com/icon/84804/wifi

Purpose • Want to make an embedded application where a wired connection isn't practical, things to consider with a wireless solution: o o o Antenna Frequency Band Power Consumption Range Data Rate Cost

Outline 1. Antennas 2. RF Modules 3. Wi-Fi 4. Zigbee 5. Bluetooth 6. Comparison

Outline 1. Antennas a. b. c. d. e. Overview Antenna Theory Antenna Types Bandwidth & Gain Terminology 2. RF Modules 3. Wi-Fi 4. Zigbee 5. Bluetooth 6. Comparison

Why are we covering antennas? • • Antennas are used in all wireless embedded systems Some embedded applications will require you to pick an antenna You may design a PCB that will include an antenna o Having a basic understanding of how antennas work can help you pick one o This presentation will provide information to help you read an antenna spec sheet o Image taken from: http: //store. diyembedded. com/index. php? main_page=product_info&products_id=28

How does an antenna work? • Converts an electrical signal into • • electromagnetic radiation and vice versa Transmission o Radio transmitter supplies radio frequency current to antenna terminals o Antenna radiates energy from current in electromagnetic waves Reception o Antenna intercepts power from electromagnetic waves to produce voltage at its terminals, that voltage is then amplified Image taken from: http: //upload. wikimedia. org/wikipedia/commons/d/da/Felder_um_Dipol. jpg

Basic Antenna Types • Omnidirectional - Radiates • • • in all horizontal directions Patch antenna o Dipole Antennas Semi-directional - Radiates in a horizontal arc o Patch Antennas o Panel Antennas o Yagi Antennas Directional (Beam) - Radiates in one direction o Parabolic Dishes o Grid Antennas Parabolic antenna More information on antenna types can be found at: o http: //zaielacademic. net/networking_wireless/wireless_a ntennas. htm

Omnidirectional Basic Antenna Types Image taken from: http: //zaielacademic. net/networking_wireless/wireless_antennas. htm

Directional Basic Antenna Types Image taken from: http: //zaielacademic. net/networking_wireless/wireless_antennas. htm

Directional: Fresnel Zone • • Radiation from directional antenna does not travel in direct path Fresnel calculations can be found at: http: //zaielacademic. net/ networking_wireless/wire less_antennas. htm Image taken from: http: //zaielacademic. net/networking_wireless/wireless_antennas. htm

Reading Antenna Spec Sheets

Antenna Bandwidth Reading Antenna Spec Sheets • • Bandwidth - Difference between high and low cutoff frequencies Describes the range of frequencies at which an antenna can receive or transmit a signal Measured in hertz Bands located in different areas of the frequency spectrum can have the same bandwidth Images taken from: http: //www. antenna-theory. com/basics/bandwidth. php http: //upload. wikimedia. org/wikipedia/commons/6/6 b/Bandwidth_2. svg

Antenna Gain (d. Bi) Reading Antenna Spec Sheets • • Transmission o Describes how well antenna turns electrical power into electromagnetic radiation Reception o Describes how well antenna turns electromagnetic radiation into electrical power Defined as ratio of power produced by antenna from far away source over power produced by hypothetical isotropic antenna Units are decibels-isotropic (d. Bi) o G = 10 log 10 ( I A / I Q ) http: //whatis. techtarget. com/definition/decibels-relative-to-isotropic-radiator-d. Bi Image taken from: http: //www. maximintegrated. com/appnotes/index. mvp/id/3622

Receive Sensitivity and Transfer Power (d. Bm) Reading Antenna Spec Sheets • • Transfer Power - Total power over bandwidth Receive Sensitivity - The necessary radiation power needed by the receiver to pick up a signal from the transmitter Power (d. Bm) Power (W) -30 d. Bm 0. 0000010 W -20 d. Bm 0. 0000100 W -10 d. Bm 0. 0001000 W 0 d. Bm 0. 0010000 W 1 d. Bm 0. 0012589 W 2 d. Bm 0. 0015849 W 3 d. Bm 0. 0019953 W 4 d. Bm 0. 0025119 W 5 d. Bm 0. 0031628 W 6 d. Bm 0. 0039811 W 7 d. Bm 0. 0050119 W 8 d. Bm 0. 0063096 W 9 d. Bm 0. 0079433 W 10 d. Bm 0. 0100000 W 20 d. Bm 0. 1000000 W Image taken from http: //www. mobilemark. com/engineering/antenna-theory-simplified. html

Antenna Range Reading Antenna Spec Sheets • Frequency = 2442 Hz (Wi-Fi) • Transmitting power: 18 d. Bm =. 06 W @ 11 Mbps • Receiving sensitivity: -90 d. Bm = 10^(-12) W @ 11 Mbps Antenna Gain (d. Bi) Range (km) 0 . 8714 4 2. 189 7 4. 368 10 8. 7146 13 17. 3879 16 34. 693 20 87. 146 24 218. 9

Other Terms Reading Antenna Spec Sheets • • Beamwidth - The width of the angle at which an antenna will accept signals o A narrower beamwidth is desirable for a directional antenna Front to Back Ratio - describes how much a signal received behind the antenna is reduced compared to a signal received in the front Effective Aperture - Describes the effectiveness of an antenna at receiving power from radio waves (http: //en. wikipedia. org/wiki/Effective_aperture) More detailed information: http: //www. afar. net/tutorials/antennas/

• • • What We Covered So Far Antenna Theory o Transmitting o Receiving Basic Antenna Types o Omnidirectional o Directional How to read antenna spec sheets o Frequency Range o Bandwidth o Antenna Gain (d. Bi) o Antenna Senstivity (d. Bm) Calculated Antenna Range http: //www. afar. net/tutorials/antennas/

Outline 1. Overview of Antennas 2. RF Modules What are they? b. RF Module Communication c. Modulation a. 3. Wi-Fi 4. Zigbee 5. Bluetooth 6. Comparison

RF Modules • • • Integrated circuits designed to transmit and/or receive radio signals Have a radio transmitter and/or receiver An umbrella term that includes many different pieces of hardware o Several different wireless protocols are used among RF Modules Image taken from: https: //www. sparkfun. com/products/10535?

RF Module Communication • • • Antennas are used to transmit and receive data Use either wireless serial or a specific protocol Signals containing data or information are modulated Image taken from: http: //www. sciencedirect. com/science/article/pii/S 0168169909000076

Modulation • • Varying a property of a high frequency signal (carrier signal) to send information Amplitude modulation and frequency modulation used in radio Similar modulation used in simple RF Modules o Amplitude Shift-Keying (ASK) o Frequency Shift-Keying (FSK) o On-off keying (OOK) More complex modulation used for more complex protocols

Amplitude-Shift Keying (ASK) • • • Changes amplitude of the transmitted signal based on the data being sent Assigns specific amplitudes for 1's and 0's On-off Keying (OOK) is a simple form of ASK Image taken from: http: //www. ele. uri. edu/Courses/ele 436/labs/ASKn. FSK. pdf

Frequency-Shift Keying • • Changes frequency of the transmitted signal based on the data being sent Assigns specific frequencies for 1's and 0's Image taken from: http: //www. ele. uri. edu/Courses/ele 436/labs/ASKn. FSK. pdf

Outline 1. Overview of Antennas 2. RF Communication 3. Wi-Fi a. b. c. d. e. Overview Bandwidth & Data Rates MIMO Antenna Embedded Applications 4. Zigbee 5. Bluetooth 6. Comparison

Wi-Fi • Overview o “Wireless Fidelity”, exchanges data wirelessly o Wireless Local Area Networks (WLAN) based on the IEEE 802. 11 specifications i. WLAN links two or more devices using some wireless distribution method, and provides a connection through an access point to the wider internet. o Internet Access i. Wide Range (65 feet indoor, much greater outdoor) ii. High Speed (54 Mbps)

IEEE 802. 11 • • WLAN standards (2. 4, 3. 6, 5 GHz) History (Wi-Fi) o 1997, initial speed 1 and 2 Mbps o 1999, 802. 11 a/b, 20 MHz bandwidth i. a: 5 GHz, high data rate, small wavelength ii. b: 2. 4 GHz, 11 Mbps, large effective overall range 2003, 802. 11 g (54 Mbps) o 2009, 802. 11 n (MIMO), both 2. 4 and 5 GHz, 54 Mbps to 600 Mbps, 40 MHz bandwidth o

Image taken from: en. wikipedia. org/wiki/File: United_States_Frequency_Allocations_Chart_2003__The_Radio_Spectrum. jpg

United States Partial Frequency Spectrum Image taken from: en. wikipedia. org/wiki/File: United_States_Frequency_Allocations_Chart_2003__The_Radio_Spectrum. jpg

Wi-Fi Radio Technology • High frequency allows high data rate o 802. 11 a , 5 GHz; 802. 11 b/g, 2. 4 GHz • o Able to change frequency Efficient coding techniques o 802. 11 a/g, OFDM i. Subcarriers are orthogonal to each other ii. Eliminates the need for guard bands o 802. 11 b, CCK (complementary code keying) i. Replace the previous code in wireless digital networks ii. Transfer more data per unit time for a given signal Orthogonal Subcarriers bandwidth More information: http: //searchmobilecomputing. techtarget. com/definition/Complementary-Code-Keying

Wi-Fi Radio Technology • Multiple input Multiple output (MIMO) o Smart antenna technology i. SISO: Tradition antenna configuration using one transmitter and one receiver o Transmitting multiple data streams simultaneously and spread transmit heat o Wi. MAX, LTE… SISO scheme

Wi-Fi Antenna • • Omnidirectional Wi-Fi antenna o Multiple directions o Routers and mobile adapters o Gain: 2 to 9 d. Bi i. d. Bi - decibels relative to an isotropic (0 d. Bi) reference antenna ii. d. Bd - decibels relative to a dipole (0 d. Bd) reference antenna iii. 2. 15 d. Bi =0 d. Bd Directional Wi-Fi antenna o Extend the range in one direction o High gain (above 10 d. Bi) o More information: http: //compnetworking. about. com/od/homenetworkh ardware/a/introduction-to-wifi-wireless-antennas. htm

Wi-Fi Antenna • Examples Yagi Antennas (0. 8 mil) i. Extend the range of outdoor hotspots in a specific directions ii. High gain, usually 12 d. Bi or higher o Cantenna (1. 2 -2 mil) i. A brand name of Wi-Fi directional antennas ii. Supports 2. 4 GHz signaling with gain up to 12 d. Bi iii. Beamwidth of about 30 degrees o Others i. Backfire antennas ii. Parabolic or dish antennas iii. More information: http: //www. radiolabs. com/Articles/wifio antenna. html

Wi-Fi Security • • • Security goals and strategies o mutual authentication o private communication o data integrity Wired Equivalent Privacy (WEP) IEEE 802. 11 i (WPA and WPA 2) WPA 2: supports most new Wi-Fi devices o Fully compatible o • Security Trade-Off o Embedded system: private/public access

Pros and Cons Advantages • • • Frees network devices from cables, allows for a more dynamic network to be grown Cheaper development for embedded system o price drops Backwards compatible; reliable products Security High speed o 54 Mbps Disadvantages • • • 802. 11 b/g use the 2. 4 GHz spectrum, which is crowded with other devices (Bluetooth. . . ) 802. 11 n doubles the radio spectrum/bandwidth (40 MHz) Power consumption o o o 0. 5 -1 w, chipsets 1 -2 w, wifi device 4 -5 w, router Limited network range Security risks (configure)

Wi-Fi for Embedded System • • • Control applications where wired connection are too costly or inconvenient Emergency applications that require immediate and transitory setup Mobile applications Camera applications Communication with other Wi-Fi devices

Application • • Internet Access o Hotspots City-wide Wi-Fi Campus-wide Wi-Fi Direct computer-to-computer communications o Wireless ad hoc network

Outline 1. Overview of Antennas 2. RF Communication 3. Wi-Fi 4. Zigbee Overview b. Data Rates, Power, & Broadband c. Communication Protocol d. Applications a. 5. Bluetooth 6. Comparison

Zigbee • • What is it? o A protocol for high level communication over digital radios, based in IEEE 802. 15. 4 Why “Zigbee”? o The name “Zigbee” refers to the dance bees do to communicate http: //openlearn. open. ac. uk

What is Zigbee? • • Zigbee (low-power) o Specializes in using low power, low speed, long battery life radios for transmission Zigbee Pro o Higher power, higher range, shorter battery life. Still compatible with regular Zigbee

Zigbee (low power) • • • 250 kbits/s Operates at 2. 4 GHz Up to 400 ft, unobstructed 45 m. A transmit current 2. 1 -3. 6 supply Voltage Zigbee Pro • • • 250 kbits/s Operates at 2. 4 GHz Up to 1 mi, unobstructed 295 m. A transmit current 3. 0 -3. 4 supply Voltage

Antennas • • U. FL o When Size is a concern o Up to 6 GHZ o Can be surface mounted or printed on the board o Omnidirectional ¼ Wave Whip o Omnidirectional RP-SMA o Depending on size, rated up to 18 GHz, 26. 5 GHz o Omnidirectional More information: http: //www. sparkfun. com/datasheets/Wireles s/Zigbee/XBee-Datasheet. pdf

Zigbee Products • • If someone wants to build a Zigbee compliant product must have their design base on the Zigbee based stack protocol Zigbee Alliance, a collection of companies that publish the Zigbee standard, are in charge of design

Stack Architecture • • • Physical layer implemented through IEEE 802. 15. 4, which defines the frequency bands of operation, 2. 4 GHz, 915 Mhz, 868 Mhz. o maximum length of packet, 127 bytes. Stack Features o NWK – Network layer support, mechanism to manage the networks. Meshes, routing of data, discovery and maintenance, etc. o APS – Application support sublayer, mechanism to forward messages between devices. o ZDO – Zigbee device object, defines the role of the node within the Zigbee network. o SSP- Manages security protocols. Two types; residential, one NWK key and commercial, two NWK keys. Application Profiles- Custom software programmed by the user

Zigbee Networking

Pros and Cons Advantages • • Mesh networking allows for longer distance communication With no central point failure, communication is more robust Low power and long life Low cost Disadvantages • • Smaller range than Wi-Fi Lower data rates than bluetooth and Wi-Fi

• • • Applications Because of Zigbee characteristics, applications focus on monitoring. Example, Home Automation o Saves on energy bills by monitoring temperature, motion in rooms. o Can manage home security. Example, Health Care o Targeted at persons with chronic health care issues. o Pill dispenser and monitor. o Sensor that transmit alarm calls if triggered.

Outline 1. Overview of Antennas 2. RF Communication 3. Wi-Fi 4. Zigbee 5. Bluetooth Overview b. Antennas c. Applications a. 6. Comparison

Bluetooth A Quick Overview • • • Designed as a wireless cable replacement “Bluetooth” was the early name for the special interest group Uses radio waves to transmit over short distances. PAN’s of up to 164 feet

Networks • Piconet – One host device with up to 7 active slave devices • Scatternet – Collection of piconets wherein host devices are master of their respective piconet, but slave to other devices

Versions • • • Bluetooth 1. 1 o Ratified in IEEE 802. 15. 1 standard. Buggy but operational Bluetooth 1. 2 o o o Higher data rates of 721 Kbit/s Adaptive frequency hopping Faster connection and discovery Bluetooth 2. 0 o Introduction of EDR (Enhanced Data Rates) of 2. 1 Mbits/s. Achieved by using Gaussian frequency shift keying o o Lower power consumption Backwards compatible with 1. versions Bluetooth 2. 1 o o Also backward Compatible. o Secure Simple Pairing, improves pairing and connectivity of Bluetooth device and host. Extended inquiry response, provides information regarding connectivity during device inquiry. Bluetooth 3. 0 o o Ultra wide broadband allows for even faster data rates of up to 24 Mbit/s. Enhanced power control allows for very low power consumption. Bluetooth 4. 0 o Ultra low power consumption during idle state.

Antennas • • PIFA Antenna o Printed antenna, usually about 20 to 25 mm in length o Placed on the edge of PCB o 2. 4 GHz Ceramic Dielectric Antenna o Smaller than PIFA o Forms a concentrates electric field by wrapping around a high-dk ceramic slab LMX 9820/A Antenna o About 14 x 10 mm in size o Metal shielding protects the components from the electric field of antenna LMX 9830 Antenna o About 6 x 9 mm in size o Unshielded, so it cannot be placed near other elements

Applications • • • Characteristics make it ideal for short range PAN applications General, wireless communication between wireless devices Example, connectivity between wireless mouse and laptop

Outline 1. Overview of Antennas 2. RF Communication 3. Wi-Fi 4. Zigbee 5. Bluetooth 6. Comparison

Comparison Wifi Zigbee Bluetooth IEEE Standard 802. 11 802. 15. 4 802. 15. 1 Frequency Band 2. 4, 3. 6, 5 GHz 2. 4 Ghz Data Rates 54 Mbits/s 250 Kbits/s 1 Mbit/s Power Consumption High Very Low, Low Medium Antennas Yagi Antenna; Cantenna U. FL, 1/4 Wave Whip, RP-SMA PIFA , Ceramic Dielectric, LMX 9830 Range 500 ft Outdoor 400 ft, 1 mi Outdoor 35 -300 ft Outdoor Cost 20 -80$ (module) 20 -30$* 40 -100$* Application Example Internet Access (Hotspots); Mobile Applications Home Automation Healthcare Monitoring Wireless mouse, Wireless headset *Source: Digikey

References Antennas • http: //k 9 erg. tripod. com/theory. htm • http: //en. wikipedia. org/wiki/Radio_frequency • http: //en. wikipedia. org/wiki/Antenna_(radio) • http: //www. mobilemark. com/engineering/antenna-theory-simplified. html • http: //www. tselectronic. com/tech_notes/antenna_spec. php • http: //www. afar. net/tutorials/antennas/ • http: //www. qsl. net/co 8 tw/vertical. htm • http: //electronics. howstuffworks. com/question 490. htm • http: //zaielacademic. net/networking_wireless/wireless_antennas. htm • http: //en. wikipedia. org/wiki/Antenna_aperture RF Modules • http: //en. wikipedia. org/wiki/Rf_module Wi-Fi • http: //www. creativeworld 9. com/2011/03/abstract-and-full-paper-on-wi-fi. html • http: //en. wikipedia. org/wiki/Wi-Fi • http: //compnetworking. about. com/od/homenetworkhardware/a/introduction-to-wifi-wireless-antennas. htm • http: //www. radiolabs. com/Articles/wifi-antenna. html Zigbee • http: //www. sparkfun. com/datasheets/Wireless/Zigbee/XBee-2. 5 -Datasheet. pdf • http: //www. lsr. com/downloads/products/330 -0098. pdf • http: //www. stg. com/wireless/Zig. Bee_comp. html • http: //en. wikipedia. org/wiki/Zigbee Bluetooth • http: //en. wikipedia. org/wiki/Bluetooth

Questions?