Connected Manufacturing Forum Wireless 101 usa.siemens.com/industry
Why Wireless? Wireless communication can be used to provide additional flexibility for today s automation applications. Standardization in wireless communications has created some of the easiest ways to connect devices. Wireless communications have made the previously impossible, Possible! Page 2
Wireless technologies Here are a few technologies that provide wireless data connectivity Page 3
What is Wi-Fi Definition: Wi-Fi is the industry name for wireless LAN (WLAN) communication technology related to the IEEE 802.11 family of wireless networking standards. Page 4
What is WLAN Wireless Local Area Network Technologies that allow data transmission wirelessly using radio waves Smart phone Internet Laptop Router Access point PC Page 5
Wireless History Victor Hayes is considered the father of Wi-Fi He established and chaired the IEEE 802.11 working group for wireless local area networks John O'Sullivan, an Australian radio astronomer developed the key patent used in wireless LAN. This key technology was developed after a failed experiment to detect exploding mini black holes the size of an atomic particle Page 6
What is IEEE 802.11 Specifications maintained by the Institute of Electrical and Electronics Engineers. Define a Wireless Local Area Network Page 7
Interaction with other IEEE 802 layers IEEE not only defines the standard for WLAN but it also defines the standard for Ethernet (IEEE 802.3) They have defined both standards to work seamlessly together This means it is easy to transition between wired network segments and a wireless network segments Internet PC Page 8
What do the 802.11 Specifications cover? A family of wireless communication techniques that use the same basic protocol 802.11-1997 The first wireless standard 802.11b 2.4 GHz 802.11a 5 GHz 802.11g 2.4 GHz Did you know? The 2.4 GHz band is the same frequency range used by some microwave ovens, cordless phones, Bluetooth devices and amateur radio? 802.11n Uses both the 2.4 GHz and 5 GHz band Note: These are all unlicensed Radio Frequency bands for communication devices Page 9
Wi-Fi Performance 100 Wi-Fi typical achievable data throughput Mbit/s 0 802.11-1997 802.11b 802.11a 802.11g 802.11n 1997 1999 1999 2003 2009 Page 10
2.4 GHz channels (US) There are 14 available channels Limited to channels 1-11 in the US Each channel is effectively 22 MHz wide This means that there are only 3 non overlapping channels 1, 6, 11 NOTE: The actual frequency ranges for each band vary slightly from country to country. Page 11
Channel Planning If necessary, frequencies can be staggered to prevent overlap Area to cover with WLAN Page 12
5 GHz channels (US) Indoor use only channels 36, 40, 44, 48 Indoor and outdoor channels 149, 153, 157, 161, 165 Power limited to 1W Did you know? The 5 GHz band has more usable channels and is less crowded compared to the 2.4 GHz band 36 40 44 48 149 153 157 161 165. 20 MHz NOTE: The allowable channels vary from country to country Page 13
Summary 2.4 GHz vs. 5 GHz Which band is better for industrial communications? 2.4 GHz band - Too Crowded - Effectively there are only 3 non-overlapping channels (in the US) 5 GHz band + Less crowded + Smaller antenna + More non-overlapping channels Page 14
Access Points and Clients Access point - a base station that allows other WLAN devices to connect and get access to a network Client - WLAN devices that connect to an Access point Internet Access Point Client Client Client Client Page 15
Half Duplex WLAN devices communicate in half duplex mode The radios cannot talk and listen at the same time Access Point Did you know? Only one client or access point can talk at a time Like Internet using a Walkie-Talkie Client Client Client Client Page 16
Half Duplex Only one client or access point can talk at a time As more clients associated with the access point, each one will get less overall bandwidth Internet Access Point Client Client Client Client Page 17
WLAN Modes of Operation Client Access Point Client Client Access Point Access Point Ad-hoc mode: Peer-to-peer Clients must deal with collisions themselves Without access points Client Client Infrastructure mode: Stations (clients) communicate through a base station (access point) Collisions are handled by the access point WDS mode: The Wireless Distribution System (WDS) allows direct connections between base stations (access points), which can be used like backbone connections Page 18
Roaming Moving WLAN clients can be supported along several access points. An access point can only cover a certain area or cell Access Point Access Point Access Point Roaming When a client moves around, it Client may move from one cell to another Roaming Page 19
Components of a WLAN device The connecting cables All of these pieces added together will determine the size and shape of the RF field If the antenna are not The radio - (Access Point connected directly to the or Client) radios, connecting cables can This device acts as an be used. amplifier The antenna and creates a NOTE: They will decrease certain amount of power for the amount of actual power the Used RF field to create the RF field at the antenna Page 20
Radios The radios in an access point or client produce the power for the RF field (Radio Frequency field) Page 21
Connecting cables Coax cable is used to connect the antenna to the radio The connection cable is lossy Each foot of cable will reduce the power that will be available to the antenna Place your radios close to the antenna! Page 22
Antenna Types OMNI directional antennas send and receive the signal in/ from radius of 360 (horizontal pattern) Directional antennas send and receive the signal in/ from a sector with a specific angle (horizontal pattern) have a gain like a speaking tube, but NO amplification they only concentrate the signal in a small lobe when sending AND receiving A good video on RCOAX can be found here RCoax cable a special, stretched OMNI directional antenna http://www.youtube.com/ watch?v=avj-shhfbyi Page 23
Antenna There are many types of antenna available These different antenna shape the radio field in different ways Field Plots are used to diagram the RF field pattern Omni-Directional Antenna Directional Antenna Page 24
Antenna Field Plots The Antenna would be physically located at the center of the plot The plot show the field focused in a specific direction. This is the main lobe Most directional antenna also produce secondary side lobes Page 25
Antenna Gain Antenna gain is passive pain Antenna do not amplify or create more power Antenna can focus or shape the RF field in a favorable direction The amount of focus is a certain direction is called antenna gain Antenna gain is measured in decibels This directional antenna has focused RF field. This antenna has gain Almost no gain The Omni directional (dipole) antenna has an evenly distributed RF field around the antenna It has almost no gain The perfect Omni Directional antenna would produce a perfect circle and have no Has gain gain Page 26 Dipole Antenna Horizontal Field Plot Directional Antenna Horizontal Field Plot
When to use WLAN? WLAN can be used to solve some of these tough application issues When wires won t reach Cat 5 or 6 copper only usable up to 300 feet When wires cost too much to run When one or more parts move Page 27
Application Example Walt Disney - Midway Mania attraction Need to keep the RF field out of the guest area as much as possible Security Need to manage how many vehicles can connect to each access point at one time Prevent data starvation Page 28
Application Example Sea World Antarctica attraction Vehicles are free roaming and do not follow a fixed path Need area coverage with RF field Need to manage how many vehicles can connect to each access point at one time Prevent data starvation Page 29
Thank You for Your Attention! Connected Manufacturing Forum Website: http://www.industry.usa.siemens.c om/automation/us/en/connectedmanufacturing/pages/connectedmanufacturing.aspx Answers for industry. Siemens Industry Inc. 2013. All rights reserved. Page 30 US I IA SC FA