This list compiles some the proposed 802.11(x) standards. The two bands (2.4 Ghz and 5 Ghz) have developed many variations such as improved security (i), QOS (e) and speed (g). Below that is a glossary of common telecommunications terms. See also TelecomunicationsCompanies.

Network Magazine had an excellent review of different 802.11x standards. The explainations (below) are largely theirs:

The various IEEE 802.11 standards can be confusing. In addition to the three main specifications that define complete wireless LAN systems (802.11a, 802.11b, and now 802.11g), the IEEE is working on enhancements that mitigate weaknesses in the existing protocols. These aren't new wireless LAN systems, but rather extensions that will eventually be applied to one or all of the existing three.

802.11b is good old 2.4 Ghz Wi-Fi. It has three lower data rates (5.5, 2, and 1Mbit/sec) and is the basis for most wireless lans. While 11Mbps is the advertised speed, useable rates are about half that and actual throughput can be bring it down to one quarter. There is 85 Mhz available using 11, 22Mhz wide channels. Most overlap so they can't be used next to each other - only 3 channels don't overlap. See ChannelFrequencyChart for details.

802.11a Both 802.11 (a & b) were conceived about the same time but the higher (5Ghz) frequency was took longer to bring to market. 801.11a can ratched down seven steps (48, 36, 24, 18, 12, 9, and 6Mbits/sec). The 5 Ghz band has 300 Mhz of spectrum 5.715-5.735 and 5.8 (something). The first 100 is indoor only, the next 100 is indoor/outdoor and the last 100 Mhz is outdoor. Each 100 Mhz band has four channels.

802.11d aims to produce versions of 802.11b that work at other frequencies, making it suitable for parts of the world where the 2.4GHz band isn't available. Most countries have now released this band, thanks to an ITU recommendation and extensive lobbying by equipment manufacturers. The only holdout is Spain, which may follow soon.

802.11e will eventually add QoS capabilities to 802.11 networks. It replaces the Ethernet-like MAC layer with a coordinated Time Division Multiple Access (TDMA) scheme, and adds extra error-correction to important traffic. The technology is similar to Whitecap, a proprietary protocol developed by Sharewave and used in Cisco's 802.11a prototypes. A standard was supposed to be finalized by the end of 2001, but has run into delays thanks to arguments over how many classes of service should be provided and exactly how they should be implemented.

802.11f tries to improve the handover mechanism in 802.11 so that users can maintain a connection while roaming between two different switched segments (radio channels), or between access points attached to two different networks. This is vital if wireless LANs are to offer the same mobility that cell phone users take for granted.

802.11g uses the COFDM modulation of 5 Gig in the 2.4 Gig band. The advantage is longer range and compatibility with 11b. The disadvantage is interference from the restriction of only 3 useable channels

802.11h attempts to add better control over transmission power and radio channel selection to 802.11a. Along with 802.11e, this could make the standard acceptable to European regulators.

802.11i deals with 802.11's most obvious weakness: security. Rather than WEP, this will be an entirely new standard based on the Advanced Encryption Standard (AES), the U.S. government's "official" encryption algorithm. The Task Group in charge hasn't yet chosen an authentication protocol: Some members want to use a new system called Offest Codebook (OCB), but this is covered by three separate patents; other members would prefer one that everyone can adopt royalty-free.

802.11j is so new that the IEEE hasn't officially formed a task group to discuss it, let alone produced a draft standard. It's supposed to cover how 802.11a and HiperLAN2 networks can coexist in the same airwaves.

Glossary of Terms

10 Gigabit Ethernet (10GbE) – The emerging IEEE standard for Ethernet operation at 10 Gbps.

10 Gigabit Ethernet Alliance(10GEA) - An organization promoting the rapid deployment of 10GbE.

10 Gigabit Media Independent Interface (XGMII) – The interface between the media dependent and media independent parts of the Ethernet protocol stack.

Add/Drop Multiplexer (ADM) - A multiplexer capable of extracting or inserting lower-rate signals from a higher-rate multiplexed signal without completely demultiplexing the signal.

American National Standards Institute (ANSI) - The coordinating body for voluntary standards groups within the United States. ANSI is a member of the International Organization for Standardization (ISO).

Application Program Interface (API) - Means of communication between programs to give one program transparent access to another.

Asynchronous Transfer Mode (ATM) - A cell-based, fast-packet technology that provides a protocol for transmitting voice and data over high-speed networks. ATM is a connection-oriented technology used in both LAN and WAN environments. It is asynchronous in that the recurrence of cells depends on the required or instantaneous bit rate.

Border Gateway Protocol (BGP) - Protocol for communications between a router in one autonomous system and routers in another.

Carrier Sense Multiple Access/Collision Detection (CSMA/CD) - A channel access mechanism wherein devices wishing to transmit first check the channel for a carrier. If no carrier is sensed for some period of time, devices can transmit. If two devices transmit simultaneously, a collision occurs and is detected by all colliding devices, which subsequently delays their retransmissions for some random length of time. CSMA/CD access is used by Ethernet and IEEE 802.3.

Data Link Layer - Layer 2 of the OSI reference model. This layer takes a raw transmission facility and transforms it into a channel that appears, to the network layer, to be free of transmission errors. Its main services are addressing, error detection, and flow control.

Differential Services IETF standard (DiffServ) – A set of IETF standards designed to allow QoS support in IP networks by providing a means to distinguish among classes of service.

Ethernet - (1) A baseband LAN specification invented by Xerox Corporation and developed jointly by Xerox, Intel, and Digital Equipment Corporation. Ethernet networks operate at 10 Mbps using CSMA/CD to run over coaxial cable. Ethernet is similar to a series of standards produced by IEEE referred to as IEEE 802.3. (2) A very common method of networking computers in a local area network (LAN). Ethernet will handle about 10,000,000 bps and can be used with almost any kind of computer.

Fast Ethernet - Term given to IEEE 802.3u (called Fast Ethernet) for Ethernet operating at 100 Mbps over Cat-3 or 5 UTP.

Fiber Distributed Data Interface (FDDI) - An emerging high-speed networking standard. The underlying medium is fiber optics, and the topology is a dual-attached, counter-rotating Token Ring. FDDI networks can often be spotted by the orange fiber "cable." The FDDI protocol has also been adapted to run over traditional copper wires. An ANSI-defined standard specifying a 100 Mbps token-passing network using fiber-optic cable. Uses a dual-ring architecture to provide redundancy.

Fiber Optic Cable - A transmission medium that uses glass or plastic fibers, rather than copper wire, to transport data or voice signals. The signal is imposed on the fiber via pulses (modulation) of light from a laser or a light-emitting diode (LED). Because of its high bandwidth and lack of susceptibility to interference, fiber-optic cable is used in long-haul or noisy applications.

Fiber Optics - A method for the transmission of information (sound, pictures, data). Light is modulated and transmitted over high purity, hair-thin fibers of glass. The bandwidth capacity of fiber optic cable is much greater than that of conventional cable or copper wire.

Gigabit Ethernet - A 1Gbps standard for Ethernet.

Gigabit Ethernet Alliance - An association of Gigabit Ethernet manufacturers and suppliers formed for the purpose of promoting Gigabit Ethernet Technology.

Gigabits Per Second (Gbp/s) - Billion bits per second. A measure of transmission speed.

IEEE 802.1p - An IEEE draft standard that extends the 802.1D Filtering Services concept to provide both prioritized traffic capabilities and support for dynamic multicast group establishment.

IEEE 802.2 - IEEE LAN protocol that specifies an implementation of the logical link control sub layer of the link layer. IEEE 802.2 handles errors, framing, flow control, and the Layer 3 service interface.

IEEE 802.3u - IEEE LAN protocol that specifies an implementation of the physical layer and MAC sub layer of the link layer. IEEE 802.3 uses CSMA/CD access at a variety of speeds over a variety of physical media. One physical variation of IEEE 802.3 (10Base5) is very similar to Ethernet.

IEEE 802.5 - IEEE LAN protocol that specifies an implementation of the physical layer and MAC sub layer of the link layer. IEEE 802.5 uses token passing access at 4 or 16 Mbps over shielded twisted pair wiring and is very similar to IBM Token Ring.

IEEE 802.6 - Standards being developed by IEEE to govern metropolitan area networking.

Institute of Electrical and Electronic Engineers (IEEE) - Professional organization that defines network standards. IEEE LAN standards are the predominant LAN standards today, including protocols similar or virtually equivalent to Ethernet and Token Ring.

Management Information Base (MIB) - A database of information on managed objects that can be accessed via network management protocols such as SNMP and CMIP.

Media Access Control (MAC) - IEEE specifications for the lower half of the data link layer (layer 2) that defines topology dependent access control protocols for IEEE LAN specifications.

Media Access Control Sub Layer (MAC Sub layer) - As defined by the IEEE, the lower portion of the OSI reference model data link layer. The MAC sub layer is concerned with media access issues, such as whether token passing or contention will be used.

Media Attachment Unit (MAU) - In IEEE 802.3, a device that performs IEEE 802.3 Layer 1 functions, including collision detection and injection of bits onto the network.

Media Independent Interface (MII) - The standard in Ethernet devices to transparently interconnect the MAC sublayer and the PHY physical layer, regardless of media.

Media Interface Connector (MIC) - FDDI de facto standard connector.

Megabit (Mb/s) - One million bits per second.

Megabits per Second (Mbps) - A digital transmission speed of millions of bits per second.

Metropolitan Area Network (MAN) - A data communication network covering the geographic area of a city (generally, larger than a LAN but smaller than a WAN).

Multimode Fiber - Optical fiber with a core diameter of 62.5 or 50 microns. Dispersion of light is greater than single mode fiber so distances are less.

Multimode Fiberoptic Cable (MMF) - Fiberoptic cable in which the signal of light propagates in multiple modes or paths. Since these paths may have varying lengths, a transmitted pulse of light may be received at different times and smeared to the point that pulses may interfere with surrounding pulses. This may cause the signal to be difficult or impossible to receive. This pulse dispersion sometimes limits the distance over which a MMF link can operate supporting propagation of multiple frequencies of light.

Multiple Protocol Label Switching (MPLS) – A set of IETF standards that are designed to allow packet flows to be switched on the basis of labels instead of the full destination addresses, thereby promoting higher performance and allowing traffic engineering.

Open Shortest Path First (OSPF) – A routing protocol used in IP networks.

Operation Support System (OSS) – The management subsystem for provider-based networks.

Operations Administration Maintenance and Provisioning (OAM&P) – Tasks performed by the management and administrative systems in a network, especially with reference to public networks.

Optical Add Drop Multiplexer (OADM) – An ADM used with fiber optics (see ADM).

Optical Cable Level 3 (OC-3) - Defined standard for the optical equivalent of Synchronous Transport Signal 3 (STS 3) transmission rate or STS 3c Synchronous Optical Network Transport Systems (SONET) transmission rate. The signal rate for these standards is 155.52 Mbps.

Optical Carrier 1 (OC-1) - ITU-ISS physical standard for optical fiber used in transmission systems operating at 51.84 Mbps.

Optical Carrier 3 (OC-3) - Optical Carrier level 3, SONET rate of 155.52 Mbit/s, matches STS-3.

Optical Carrier- N (OC-N) - Higher SONET level, N times 51.84 Mbit/s.

Physical Coding Sublayer (PCS) – One of the sublayers defined for the Ethernet protocol stack.

Physical Layer (PHY) - The bottom layer of the OSI and ATM protocol stack, which defines the interface between ATM traffic and the physical media. The PHY consists of two sublayers: the transmission convergence (TC) sublayer and the physical medium-dependent (PMD) sublayer.

Physical Medium Dependent (PMD) - A sub layer of the physical layer that interfaces directly with the physical medium and performs the most basic bit transmission functions of the network.

Points of Presence (POP) - A term used by Internet service providers to indicate the number of geographical locations from which they provide access to the Internet.

Protocol Data Unit (PDU) - A discrete piece of information like a frame or a packet in the appropriate format for encapsulation and segmentation in the payload of a cell.

Quality of Service (QoS) - Term for the set of parameters and their values which determine the performance of a given virtual circuit.

Shared Ethernet - Conventional CSMA/CD Ethernet configuration to which all stations are attached by a hub and share 10 or 100 Mbps of bandwidth. Only one session can transmit at a time. This is the most popular network type today

Single-mode Fiber - Also called monomode. Single-mode fiber has a narrow core that allows light to enter only at a single angle. Such fiber has higher bandwidth than multimode fiber, but requires a light source with a narrow spectral width (for example, a LASER).

Synchronous Digital Hierarchy (SDH) - ITU-TSS international standard for transmission over optical fiber.

Synchronous Optical Network (SONET) - A set of standards for transmitting digital information over optical networks. "Synchronous" indicates that all pieces of the SONET signal can be tied to a single clock. A CCITT standard for synchronous transmission up to multigigabit speeds

Time Division Multiplexing (TMD) – A form of transmission in which different flows are combined on the basis of time slots.

Transparent Bridging - Bridging scheme preferred by Ethernet and IEEE 802.3 networks in which bridges pass frames along one hop at a time based on tables associating end nodes with bridge ports. Transparent bridging is so named because the presence of bridges is transparent to network end nodes.

Transport Control Protocol/Internet Protocol (TCP/IP) - A protocol (set of rules) that provides reliable transmission of packet data over networks.

Wide Area Network (WAN) - A network which encompasses interconnectivity between devices over a wide geographic area. Such networks would require public rights-of-way and operate over long distances.

Wave Division Multiplexing (WDM) – A technology that allows multiple wavelengths to be multiplexed over a single strand of fiber. Comes in various forms including Dense and Wide depending on the number of wavelengths involved


DifferentStandards (last edited 2007-11-23 18:00:53 by localhost)