Networking (Tutorial-8) IEEE Standards

IEEE INTRODUCTION

• Institute of Electrical And Electronics professional organization for the advancement of technology related to electricity. 
• Formed in 1963 by the merger of IRE( Institute of Radio Engineers ) and AIEE(American Institute of Electrical Engineering) 
• IEEE is one of the leading standards-making organizations in the world. IEEE performs its standards making and maintaining functions through the IEEE Standards Association(IEEE-SA). 

IEEE Standards

• The Institute of Electrical and Electronics Engineers Standards Association (IEEE-SA) is a leading developer of global industry standards in a broad-range of industries, including: 
• Power and Energy 
• Biomedical and Healthcare 
• Information Technology 
• Telecommunications 
• Transportation 
• Nanotechnology 
• Information Assurance 

Development of IEEE Standards

• The IEEE standards development process can be broken down into seven basic steps, as follows: 
• Securing Sponsorship 
• Requesting Project Authorization 
• Assembling a Working Group 
• Drafting the Standards 
• Balloting 
• Review Committee 

IEEE 802

• IEEE 802 refers to a family of IEEE standards dealing with local area networks and metropolitan area networks. 
• The services and protocols specified in IEEE 802 map to the lower two layers (Data Link and Physical) of the seven-layer OSI networking reference model. In fact, IEEE 802 splits the OSI Data Link Layer into two sub-layers named Logical Link Control (LLC) and Media Access Control (MAC) , so that the layers can be listed like this: 
• Data link layer 

1. LLC Sublayer 
2. MAC Sublayer 

• Physical layer 

• IEEE 802.1-Bridging (networking) and Network Management 
• IEEE 802.2-Logical link control 
• IEEE 802.3-Ethernet 
• IEEE 802.4-Token bus 
• IEEE 802.5-Defines the MAC layer for a Token Ring 
• IEEE 802.6-Metropolitan Area Networks 
• IEEE 802.7-Broadband LAN using Coaxial Cabled 
• IEEE 802.8-Fiber Optic TAG 
• IEEE 802.9-Integrated Services LAN 
• IEEE 802.10-Interoperable LAN Security 
• IEEE 802.11 a/b/g/n-Wireless LAN (WLAN) & Mesh (Wi-Fi certification)
• IEEE 802.12-demand priority 
• IEEE 802.13-Used for 100Base-X Ethernet 
• IEEE 802.14-Cable Modem 
• IEEE 802.15-Wireless PAN 
• IEEE802.15.1-Bluetoothcertification 
• IEEE 802.15.2-IEEE 802.15 and IEEE 802.11 coexistence 
• IEEE 802.15.3-High-Rate WPAN certification 
• IEEE 802.15.4-Low-rate WPAN certification 
• IEEE 802.15.5-Mesh networking for WPAN 
• IEEE 802.16-Broadband Wireless Access (WiMAX certification)

IEEE 802.11

IEEE 802.11 is a set of standards carrying out wireless local area network (WLAN) computer communication in the 2.4, 3.6 and 5 GHz frequency bands. They are created and maintained by the IEEE LAN/MAN Standards Committee (IEEE 802)

• 802.11a — an extension to 802.11 that applies to wireless LANs and provides up to 54-Mbps in the 5GHz band. 802.11a uses an orthogonal frequency division multiplexing encoding scheme rather than FHSS or DSSS. 
• 802.11b — an extension to 802.11 that applies to wireless LANS and provides 11 Mbps transmission in the 2.4 GHz band. 802.11b uses only DSSS. 802.11b was a 1999 ratification to the original 802.11 standard, allowing wireless functionality comparable to Ethernet. 
• 802.11e — a wireless draft standard that defines the Quality of Service support for LANs, and is an enhancement to the 802.11a and 802.11b wireless LAN (WLAN) specifications. 802.11e adds QoS features and multimedia support to the existing IEEE 802.11b and IEEE 802.11a wireless standards, while maintaining full backward compatibility with these standards.
• 802.11g — applies to wireless LANs and is used for transmission over short distances at up to 54-Mbps in the 2.4 GHz bands. 
• 802.11n — 802.11n builds upon previous 802.11 standards by adding multiple-input multiple-output. The additional transmitter and receiver antennas allow for increased data throughput through spatial multiplexing and increased range by exploiting the spatial diversity through coding schemes like Alamouti coding. The real speed would be 100 Mbit/s (even 250 Mbit/s in PHY level), and so up to 4-5 times faster than 802.11g.

Frequency Hopping and Direct Sequence Spread Spectrum Techniques

• Spread Spectrum used to avoid interference from licensed and other non-licensed users, and from noise, e.g., microwave ovens 

Frequency Hopping (FHSS)

• Using one of 78 hop sequences, hop to a new 1MHz channel (out of the total of 79 channels) at least every 400milliseconds 
• Requires hop acquisition and synchronization 
• Hops away from interference 

Direct Sequence (DSSS)

• Using one of 11 overlapping channels, multiply the data by an 11-bit number to spread the 1M-symbol/sec data over 11MHz 
• Requires RF linearity over 11MHz 
• Spreading yields processing gain at receiver 
• Less immune to interference

Media Access Methods

A media access method refers to the manner in which a computer gains and controls access to the network’s physical medium (e.g., cable). Common media access methods include the following:

• CSMA/CD 
• CSMA/CA 
• Token Passing 
• Demand Priority

CSMA-CA/CD

CSMA/CA

Carrier Sense Multiple Access With Collision Avoidance (CSMA/CA), in computer networking, is a wireless network multiple access method in which:

• a carrier sensing scheme is used. 
• a node wishing to transmit data has to first listen to the channel for a predetermined amount of time to determine whether or not another node is transmitting on the channel within the wireless range. If the channel is sensed "idle," then the node is permitted to begin the transmission process. If the channel is sensed as "busy," the node defers its transmission for a random period of time. Once the transmission process begins, it is still possible for the actual transmission of application data to not occur. 

CSMA/CD

Carrier Sense Multiple Access With Collision Detection (CSMA/CD), in computer networking, is a network access method in which:

• a carrier sensing scheme is used. 
• a transmitting data station that detects another signal while transmitting a frame, stops transmitting that frame, transmits a jam signal, and then waits for a random time interval (known as "backoff delay" and determined using the truncated binary exponential backoff algorithm) before trying to send that frame again. 

Token Ring

• Consists of a set of nodes connected in a ring. 
• Data flows in a particular direction only. 
• Data received from upstream neighbor forwarded to downstream neighbor. 
• Token – access to the shared ring 

1.    a special sequence of bits 
2.    circulates around the ring. 

• Each node receives and forwards token. 
• Frame makes its way back to sender 

1.     frame removed by sender 
2.     sender reinsert token. 

Token Ring Access Control

• Network adapter: receiver, and transmitter, and one or more bits of data storage between them. 
• When no stations have anything to transmit token circulates 
• Ring has enough storage capacity to hold an entire token. 
• 1 bit / station 

IEEE 802.5 (Token Ring )

• Token Size: 24 bits 

1. Minimum number of stations is 24 
2. Overcome this by including a monitor which adds the extra bits of delay 

• Token operation 

1. Token circulates 
2. Station seizes a token 

• Modifies a bit in the second byte of token 

1.   Station that has token transmits data 
2.   Station drains token out of the ring 
3.   Station sends data 
4.   Each packet has destination address 
5.   All stations downhill check destination address 
6.   Destination copies packet 
7.   Packet finds its way back to sending station 

Demand Priority Access Method

Demand priority is a media-access method used in 100BaseVG, a 100 megabit per second (Mbit/s) Ethernet implementation proposed by Hewlett-Packard (HP) and AT&T Microelectronics. Demand priority shifts network access control from the workstation to a hub. This access method works with a star topology. In this method, a node that wishes to transmit indicates this wish to the hub and also requests high- or regular-priority service for its transmission.
The hub is responsible for passing the transmission on to the destination node ; that is, the hub is responsible for providing access to the network. A hub will pass high priority transmissions through immediately, and will pass regular-priority transmissions through as the opportunity arises. By letting the hub manage access, the architecture is able to guarantee required bandwidths and requested service priority to particular applications or nodes.