CIS_470_Data_Communications

Simple Phase Shift Keying (PSK)

A sine wave is used to transmit digital data by shifting phase at the appropriate time A single bit is sent with each phase shift

Quadrature Phase Shift Keying (QPSK)

Two bits are transmitted at the same time using four different phases of the sine wave

FDM multiplexing

- Frequency division multiplexing (FDM) is a transmission method in which several (possibly many) signals are combined onto a single communications line or channel - An example would be cable TV. • many channels sharing the same physical wire • Each channel is assigned a frequency range in which to operate

PCM

- Pulse code modulation (PCM) converts an analog signal into a digital representation - It's one way to convert an analog signal (like music) to digital form - In PCM a digital signal is obtained by sampling the analog signal at regular points in time and converting each sample into a binary number • used to digitally encode voice and music on cell phones, CD's and DVD's

TDM multiplexing

- Time division multiplexing (TDM): multiple data streams are combined into a single signal and transmitted over the same link • a different time slot is allocated for the transmission of each channel - For Example: 8 Channels of data (each 1MB/sec) can be sent on a wire (8 MB/sec) simultaneously using TDM

WDM multiplexing

- Wave division multiplexing (WDM) is a form of multiplexing specifically for combining many optical carrier signals into a single optical fiber • Different colors of light are used to transmit signals • It's a kind of FDM but using light energy

network

A network is a group of computers that can communicate with each other so they can share information • When computers can communicate with each other they can share resources • When a server provides a resource for a client to access, this is referred to as a shared resource

collision

All devices that have a potential to send signals that will collide are said to be in the same collision domain A collision must occur within the first 64 bytes of transmission. By identifying collisions early in the transmission process, the NIC can retransmit the frame until it is successful A late collision occurs after the designated 64-byte limitation. Each NIC then uses a mathematical algorithm known as the Truncated Binary Exponential Backoff Algorithm to generate a random wait time before trying to transmit again. This maximum frame size is often referred to as the maximum transmission unit (MTU). This limits the amount of time a station is allowed to transmit and allows other stations equal access attempts at using the network

optical link

An optical link is a telecommunications link that consists of a single end-to-end optical circuit. A cable of optical fiber, possibly concatenated into a dark fiber link, is the simplest form of an optical link. Other forms of optical link can include single-"colour" links over a wavelength division multiplex infrastructure, and/or links that use optical amplifiers to compensate for attenuation over long distances. Other forms of optical links include free-space optical telecommunication links. In the rail transport sector, optical links are used in two forms depending on whether the feeding station is a main station or not. Thus main stations are called 'long halls', and all remaining stations are said to be 'short halls'.

attentuation

Attenuation is a general term that refers to any reduction in the strength of a signal. Attenuation occurs with any type of signal, whether digital or analog. Sometimes called loss, attenuation is a natural consequence of signal transmission over long distances.

encoding

In computers, encoding is the process of putting a sequence of characters (letters, numbers, punctuation, and certain symbols) into a specialized format for efficient transmission or storage. Decoding is the opposite process -- the conversion of an encoded format back into the original sequence of characters.

QAM signaling

Idea is to transmit groups of bits using both amplitude and phase

multiplexing

Multiplexing is about sharing a communications line. It combines several connections into one larger channel. There are many different types of multiplexing, the type used depends on what the media, reception equipment, and transmission can handle. The different types of multiplexing are: 1. Frequency division multiplexing (FDM) - a method of transmission in which numerous signals are combined on a single communications line or channel. 2. Wave division multiplexing (WDM) - form of frequency division multiplexing specifically for combining many optical carrier signals into a single optical fiber. 3. Time division multiplexing (TDM) - multiple data streams are combined in a single signal and transmitted over the same link by allocating a different time slot for the transmission of each channel.

Active Monitor

Removes lost or unclaimed tokens and sets the master clock signal for the ring

signaling

Signaling can be described as the use of light or sound to encode and transmit information. Multilevel signaling encodes a signal using multilple levels or states

signaling

Signaling is the communication of information between network nodes by using various "carrier" techniques • The carrier signal (electrical, light, radio wave) has some major characteristics: - amplitude - frequency - phase - wave length

inter-frame

The amount of time that an Ethernet client must wait from the end of the last transmission before beginning a new transmission on the wire

8-QAM Signal

Three bits can also be transmitted using four phase transitions and two amplitude transitions of a sine wave

8-PSK

Three bits can be transmitted at the same time using 8 phase transitions of a sine wave

8B/6T

To send information using 8B/6T encoding, the value of the data byte is compared to the values in the 8B/6T table. The remapping table has nine symbols used for starting and ending delimiters and control characters.

8B/10B encoding

is an encoding scheme in which 8-bit binary data values are represented by 10-bit symbols. The data octet is split up into the three most significant bits and the five least significant bits

LAN

• A Local Area Network (LAN) is a collection of networking equipment located geographically close together - A LAN is owned by the same company - A LAN utilizes high-speed data transfer capabilities

MAN

• A Metropolitan Area Network (MAN) combines the characteristics of both LANs and WANs - A MAN is limited by geography to a single metropolitan area - Local Access and Transport Areas (LATAs) are often used to define the boundaries for MANs

protocols

• A Protocol is a set of rules governing a given activity • Network protocols create standard methods of communications for networked devices • Standard LAN protocols include Ethernet, Token Ring, and Fibre Channel - combination of media type, signaling and communication protocol

WAN

• A Wide Area Network (WAN) is a collection of networking equipment geographically separated - Connection services, and possibly equipment, are leased from telecommunications providers such as phone companies or ISPs - Equipment runs at slower speeds compared to LANs

bridge

• A bridge can connect two different types of topologies - Does not understand anything above the Data Link layer - Moves data more rapidly - Takes longer to transmit because it analyzes each packet

hubs

• A hub is a multi-port repeater that retransmits a signal on all ports - Operates at Layer 1 of the OSI model - Can connect segments of a network

fibre channel

• A network environment that is generally used to connect high speed storage devices to computers • Three different layouts are possible for Fibre Channel technology, as follows: - Point-to-point - Arbitrated loop - Fabric • Point-to-point is one of the most common configurations in Fibre Channel - It is used to connect external drive arrays, printers, and other hardware component resources to servers • An arbitrated loop (AL) has become the preferred configuration for Fibre Channel - It is a mixture of both Ethernet and Token Ring topologies - It can support as many as 127 devices • Fibre Channel configured in a fabric is used to connect as many as 16,777,216 devices in a switched configuration - Unlike an AL configuration, the devices in a fabric can communicate at the same time - Fibre Channel can run on fiber-optic cable and copper such as STP

4D-PAM5

• Additional methods of encoding include: - 4D-PAM5 is a four-dimensional, five-level pulse amplitude modulation. • This is a way of encoding bits on copper wires to get a 1 GB per second transfer rate when the maximum rate of a single wire is 125 MHz - A five-level signal called pulse amplitude modulation (PAM) 5 is used

network topologies

• All devices on the network compete for access on a single shared piece of media • Only one device can transmit or talk on the media at a time while all others must listen • When more than one device simultaneously tries to talk, there is competition for access to the media resulting in a collision of information • Bus topology: - Consists of computers connected by a single cable called a backbone - All the computers share in its capacity - Simplest method for connecting computers - 10Base2 or10Base5 cable is used - The more devices, the slower the network • Ring topology: - Consists of each computer, connects directly to the next one in line, forming a circle - Data travels in a clockwise direction and each machine accepts the information intended for it • Passes on the information that is for other machines • Ring topology: - Uses a token, which is actually a small packet, to send information - Every computer in the ring is responsible for either passing the token or creating a new one • Star topology: - Computers are connected to a centralized hub by a cable segment - Require more cabling than ring or bus topologies - One computer connection goes down, it does not affect the rest of the network - Much easier to move computers around or connect them to other networks • Mesh topology: - All devices are connected to each other more than once to create fault tolerance - A single device or cable failure will not affect the performance - More expensive - Requires more hardware and cabling • Star bus topology: - Computers are connected to hubs in a star formation and then the hubs are connected via bus topology - More expensive to implement - Longer distances can be covered - Networks can more easily be isolated • Star ring topology: - Data is sent in a circular motion around the star - Eliminates the single point of failure that happens in a ring topology - Uses token passing data transmission with the physical layout of a star

OSI model

• An architecture that allows the devices of different manufacturers to work together to communicate with different operating systems • This architecture determines how hardware, software, topologies and protocols exist on the network and how they operate • Physical layer: Layer 1 of the OSI reference model - Defines mechanical, functional, procedural and electrical aspects of networking - Includes things like: connectors, circuits, voltage levels and grounding - Basically the "physical" aspects of the network • Data Link layer: Layer 2 of the OSI reference model - This layer converts raw bits from the Physical layer into logical, structured data packets • Network layer: Layer 3 of the OSI reference model - Provides connectivity and path selection between two systems - Layer at which packet routing occurs • Transport layer: Layer 4 of the OSI reference model - Helps provide a virtual error-free, point to point connection so that communication between two hosts will arrive un-corrupted and in the correct order • Session layer: Layer 5 of the OSI reference model - Allows two applications on different computers to establish dialog control - Regulates which side transmits - Determines the time and length of the transmission • Presentation layer: Layer 6 of the OSI reference model - Translates data from the Application layer into a common intermediary format - Provides services such as data encryption, and compresses data • Application layer: Layer 7 of the OSI reference model - Provides services to application processes to ensure that effective communication with other application programs is possible

signaling

• Analog signaling adds information or encodes information to an Alternating Current (AC) base signal by modifying the: - frequency (FM) - signal amplitude (AM) - signal phase (PM) • Digital signaling uses discrete steps to represent information in binary format as zeros (0s) or ones (1s)

network signaling

• Baseband signaling uses pulses to transmit data at fixed rates (using NRZ, etc) - Pulses are voltage levels for copper cable - Entire bandwidth of the cable is used to transmit one data signal - Ethernet over coax cable uses baseband signaling • Baseband signaling uses pulses to transmit data at fixed rates (using NRZ, etc) - Pulses are voltage levels for copper cable - Entire bandwidth of the cable is used to transmit one data signal - Ethernet over coax cable uses baseband signaling

multiplexing

• Cables are expensive to install • It is possible send multiple signals simultaneously over the same cable • Multiplexing combines several slower signals together and transmits them on a fast channel (cable or optical link) • Some multiplexing techniques include: - TDM (time division multiplexing) - FDM (frequency division multiplexing) - WDM (wave division multiplexing)

Transmission Medium Characteristics

• Copper wire is mature technology, rugged and inexpensive; maximum transmission speed is limited • Glass fiber: •Higher speed •More resistant to electro-magnetic interference •Spans longer distances •Requires only single fiber •More expensive; less rugged • Radio and microwave don't require physical connection • Radio and infrared can be used for mobile connections

DSL

• DSL is another technology that allows the use of existing phone lines to transmit voice and data - Transmission speed depends on length of the phone line

network data direction

• Data transmitted on a media (wire, fiber,etc) can flow: - in one direction at a time (half-duplex) - in both directions simultaneously (fullduplex)

encoding digital data

• Digital data can be encoded to digital signals for transmission on a wire, optical link or radio wave • Various techniques are used depending on the media used for transmission: - NRZ (non-return to zero) - NRZ-I - Manchester - Differential Manchester • Non-Return to Zero (NRZ-L) uses two levels of signaling (bipolar signaling) - This is the most basic and simplistic method of encoding • Non-Return to Zero Inverted (NRZ-I), is a variation - If the bit is a 1, the signal transitions - If the bit is a 0, the level stays current (no transition) • Basically, these techniques code binary data into a digital signal. - the difference being exactly how the digital signal changes • Manchester is a synchronous encoding technique used to encode the clock and data of a synchronous bit stream - It uses the rising or falling edge in the middle of each bit time to indicate a zero or one • Differential Manchester is similar to Manchester encoding - there's a difference in how the signal changes between zeros and ones of the data • Additional methods of encoding include: - 4B/5B this takes data in four-bit codes and maps it to corresponding five-bit codes • This is done to guarantee no more than three 0s in a row so that synchronization is more adequate • Too many 1's or 0's in a row cause problems with the receiver • This type of encoding is very important for many devices like hard disks and DVDs

error detection

• Digital signals being transmitted can become corrupted (bit errors) by noise • Errors are caused by interference or noise • These errors can be detected using: - Parity bits - Checksums - Cyclic Redundancy Checks (CRC) - Hamming Codes

digital signaling

• Each binary digit, or bit, represents information, where a bit being a 1 means one thing, and a 0 means another • Within the system, 1's and 0's can be represented by: - voltage levels (in a coax cable) - light pulses (in an optical cable) • A digital signal can represent any type of information (data, voice info, pictures, video) - The transition from a 0 to a 1 is called the rising edge - The transition from 1 to 0 is called the falling edge • Signals change as time progresses, and this is what enables the transmission of data • Some common terms used in digital signaling: - Clock - sets the basic rate for actions in a digital circuit - Cycle -Transition of a digital signal, from the rising edge through the falling edge, until the start of the next rising edge • Other common terms used in digital signaling: - Cycle period - The amount of time required for the signal to complete one full cycle. - Frequency - the number of cycles/sec - Rise time and fall time - This measures how long it takes for the level to change from 0 to 1, or 1 to 0.

encoding and decoding

• Encoding is putting data into a standard, well understood format • Data is encoded into some form of signal to send them over a transmission medium • Once the data has been encoded and sent along a physical medium, it must be decoded on the other end • Because information can be either digital or analog, and signals can be digital or analog there are several types of encoding - Analog signals-to-analog signals - Analog signals -to-digital signals - Digital signals -to-analog signals - Digital signals -to-digital signals • Various standard types of encoding include: - Amplitude modulation (AM) is the encoding of a carrier wave by changing its amplitude proportionally to the changes of the input (data) signal - Frequency modulation (FM) is the method of encoding data by changing the instantaneous frequency of the carrier wave • Types of encoding also include: - Phase shift modulation (PSM) is when digital signals are encoded by shifting the phases of the carrier signal (typically a sine wave) • PSM is typically used for digital signaling over analog communication links, or satellite communication (radio waves)

error recovery

• Error detection and recovery is accomplished using : - Error correction codes (ECC): is a sophisticated form of checking where errors are also corrected when they are detected - The ECC is an algorithm that adds a number of specially computed check bits to the transmitted data - If an error occurs, the extra check bits are used to detect and correct the error - Examples of ECC codes are: • Hamming • Reed-Solomon • Flow control is needed when a receiving system has to tell the sending system to stop because the data is arriving too fast • Two types of flow control are generally supported: - Hardware uses a direct connection (wire) between the two devices - Software uses control bytes sent between the two devices

checksum error detection

• Error detection can be accomplished using Checksums: - A simple error-detection scheme - Each message includes an extra word (checksum) computed as the sum of words in the message - This checksum is sent along with the message - The receiver re-computes the sum of the message - If the sum value of the receiver matches the checksum transmitted, it's assumed that the complete transmission was received correctly

parity error checking

• Error detection can be accomplished using: - Parity checking: ensures when data is transmitted from one device to another there is a way to detect corrupt transactions - Idea: add an additional bit so that the number of 1 bits is either even or odd.

CRC error detection

• Error detection is accomplished using : - Cyclic Redundancy Checking (CRC) is another technique for checking errors in data that has been transmitted on a communications link - The CRC is a computation based on dividing the message a special number • actually the message is treated as a polynomial and divided by another polynomial (using modulo-2 arithmetic) - It is very reliable in detecting transmission errors and is commonly used in modems

networking technologies

• Ethernet - Most widely used technology - Variations of Ethernet are based on transmission speed - 10, 100, 1G, 10G bits/second • Token-ring - Uses a token to identify which computer on the network has the right to transmit data - Each workstation must be connected to a multistation access unit (MAU) - Not as fast as Ethernet, and may be more expensive • Fiber Distributed Data Interface (FDDI) - Reliable, but slower and costlier than Ethernet • Arcnet - Reliable, but slower token-passing technology • Asynchronous Transfer Mode (ATM) - high-speed, very reliable and very expensive used for Internet backbones • uses connection-oriented switches to permit senders and receivers to communicate by establishing a dedicated circuit • Wireless LAN (WLAN) - No cables used to connect nodes to the network - Data is transmitted via radio signals of infrared

FDDI

• Fiber Distributed Data Interface (FDDI) is another token-passing environment that relies on a dual ring configuration for fault-tolerance - In addition to its ability to recover from a primary ring failure FDDI also functions at 100 Mbps

frame relay

• Frame Relay is a very popular high-speed packet switching MAN/WAN protocol - Frame Relay is a subscriber-based WAN service - A service provider connects a company into the provider's network by using Data Terminating Equipment (DTE) - The DTE connects into the service provider's Data Communications Equipment (DCE) within the Frame Relay switching network

telephony networks

• In a Public Switched Telephone Network (PSTN), a dedicated end-to-end circuit is allocated for each call - Conventional phone service uses an endto-end circuit (circuit switching)

telephone networks

• In a Voice over IP (VoIP) network, voice data is compressed and carried in data packets (packet switching) - both data and voice can be transmitted on the same computer network • VoIP network can carry voice traffic cheaper than a switched circuit telephone network - A company can use its existing computer network for phone service • VoIP is available for home use - Vonage - need a fast Internet connection - not as reliable as POTS

ISDN

• Integrated Services Digital Network (ISDN) is a circuit-switching technology similar in function to public switched telephone network (PSTN) - When using ISDN, you dial a number just as with PSTN but the signal is digital instead of analog • The two types of ISDN service are: - Basic Rate Interface (BRI) which is composed of two 64-kbps B channels and one 16-kbps D channel - Primary Rate Interface (PRI) which is composed of twenty-three 64-kbps channels and one 64-kbps D channel

MANs

• MANs can use a combination of the WAN/LAN technologies for interconnecting networks • MANs are limited in scope to a single metropolitan area or LATA

networking components

• Media: Coax Cables - Coaxial cable was the first type of cable used to network computers - Coaxial cables are made of a thick copper core with an outer metallic shield used to reduce external interference • Media: Twisted pair cables - Twisted pair cable comes in seven different categories. (CAT1, CAT2, ..., CAT7 ) - Twisted-pair cabling is either unshielded (UTP) or shielded (STP) • Media: fiber optic cables - Fiber was designed for transmissions at higher speeds over longer distances - Fiber uses light pulses for signal transmission, making it immune to RFI, EMI, and eavesdropping • Media: Wireless - Wireless network refers to technology that allows two or more computers to communicate using standard network protocols, but without network cabling - Wireless networking hardware requires the use of technology that deals with data transmission over radio frequencies • Wireless Standards - Most widely used wireless standard is the IEEE 802.11 standard - The IEEE standards for wireless are 802.11a and 802.11b - 802.11g is the newest

the truth about the OSI model

• Nobody really uses the OSI model in a practical networking system • It's more of a theoretical model to help folks understand networking

phase

• Phase is the comparison of a signal to another "reference" signal • Since most signals repeat themselves, the phase is the difference of the "position" of a signal from the reference signal • If the signal is, for example, a pure sine wave, the phase is measured in degrees (or radians) from a reference signal

Recall: Physical media

• Physical media - Coaxial Cable • Thick coaxial cabling • Thin coaxial cabling - Twisted Pair Cable • Unshielded twisted pair • Shielded twisted pair - Optical Cable • Multimode Fiber • Single-mode Fiber - Radio Waves • Low frequencies • Microwaves - Infrared

infrastructure protocols

• Point-to-Point Protocol (PPP) is used to connect client systems into an existing WAN infrastructure (say using a phone line) • Point-to-Point Tunneling Protocol (PPTP) is most often used when connecting users using virtual private networks (VPNs) - Layer 2 Tunneling Protocol (L2TP) is the next generation of tunneling and is similar in function to PPTP

congestion management

• Pre-allocation: - Pre-allocation schemes try to prevent congestion from happening by requiring that resources be pre-allocated before any data can be sent - This guarantees that the resources will be available to process the data when it is received • Data Discard or Load Shedding: - Data discard is a simple but inefficient way to handle congestion - If sufficient resources are not present to process existing data, the queued data is simply discarded • Isarithmic: - Isarithmic congestion control is an approach to congestion avoidance - It sets an upper limit on the number of data packets allowed to be present on the network at any one time • Choke: - Choke packets ask the sender to cut back traffic voluntary. • Traffic shaping is a range of techniques used to prioritize the transmission of data over a network link. • The idea behind shaping is to change bursts of traffic to uniform, regular traffic. • "Leaky Bucket" is an algorithm to smooth data flow

routers

• Routers operate at the Network layer of the OSI model - Forwards information to its destination on the network or the Internet - Routers maintain tables that are checked each time a packet needs to be redirected from one interface to another

amplitude

• Signals have the characteristic of "Amplitude" • This is the "height" of the signal: • Examples - voltage level - intensity level - sound level

frequency

• Signals have the characteristic of "frequency" • Simply stated: it's number of times the signal repeats itself in a unit of time • Usually measured in Hertz, which is cycles per second • Examples: - Sound pitch (bass has lower frequency than flute) - Light color (red has lower frequency that blue)

wave length

• Signals travel in some medium (examples): - Air - Coax Cable - Fiber Optic Cable • The velocity of the signal depends on the nature of the signal and the medium - example, light travels at about 186K miles/sec in space (and a bit slower in the atmosphere) • For a sine wave signal, the wave length is the distance from one peak to the next peak of the signal • Technically, the Wave Length (WL) is: - the velocity (V) of the signal divided by the frequency (F) of the signal - or WL=V/F • Example: take a signal that travels at 1000 meters/second with a frequency of 1000 cycles/second - the WL is 1 meter/cycle

switches

• Switches operate at the Data Link layer of the OSI model - Packet forwarding decisions are based on MAC addresses - Determines from the physical address (MAC address) which device a packet is intended for, and switches it directly to that device

SONET

• Synchronous Optical Network (SONET) is a synchronous TDM system controlled by a master clock. • SONET allows different data stream formats to be combined into a single synchronous high-speed signal over fiber - SONET is often used in large companies with varied WAN solutions in place or between service providers - The basic unit, or signaling rate, is 51.84 Mbps and is known as Optical Carrier 1 (OC1) - OC-256 is the fastest current standard

the internet

• The Internet was originally called ARPANET - Developed by the Department of Defense to provide a way to connect networks • Internet is a network of interconnected, yet independent networks • The protocol of the Internet is called TCP/IP

ethernet

• The architecture of Ethernet defines how network clients gain access to the medium, or network wire at the beginning of the communications process • Ethernet clients rely on carrier sense multiple access with collision detection (CSMA/CD) • No central control managing when computers transmit on the ether • Ethernet employs CSMA/CD to coordinate transmission among multiple attached computers • Carrier Sense with Multiple Access/Collision Detection • Multiple access - multiple computers are attached and any can be transmitter • Carrier sense - computer wanting to transmit tests ether for carrier before transmitting • Collisions are detected by the sender • Ethernet Media and Topology - Ethernet has evolved from a signaling rate of 10Mbps to a current speed of 1Gbps - Current implementations are utilizing 10- Gbps, though this specification is not yet formally standardized

token ring

• Token Ring defines a method for sending and receiving data between two networkconnected devices - To communicate in a token-passing environment, any client must wait until it receives an electronic token - The token is a special frame that is transmitted from one device to the next

network congestion

• Users of a common communication resource like a network must share that resource • Congestion occurs (like a traffic jam) when too many users are sharing the resource at the same time • Techniques are used to reduce congestion and make data move quickly and smoothly - Pre-allocation - Load Shedding - Isarithmic - Choke Control

WANs

• WAN technologies can be traced back to the early days of mainframe computer systems - WANs give companies the ability to leverage information technology across wide geographic areas • WANs can be classified in one of the following ways: - Circuit switching involves creating a circuit between two points when needed - Packet switching uses virtual circuits for data delivery

sliding window protocols

• Windowing is a flow-control method whereby the sender requires an acknowledgement from the receiver after a certain amount of data has been transmitted - we'll study this later when we get to TCP/IP - It requires the receiving device to communicate with the sending device by sending back an acknowledgement control byte when it receives data • Sliding Window Protocols use two different methods: - In Data Acknowledgement, both sender and receiver keep track of windows (or buffers) which are just chunks of data that needs to be transmitted • A large number of data chunks can be sent before the transmitter is sent an acknowledgement (ACK signal) by the receiver for efficiency - In Stop-and-Wait or One Bit, the sender transmits one data unit then waits for an acknowledgment before sending the next data unit • slow technique

wireless networks

• Wireless generally requires line of sight (LOS) between the two connection points • Buildings and natural formations can cause problems when trying to send and receive signals • Wireless offers freedom from monthly WAN fees, but the up-front cost for purchasing and installing wireless may be prohibitive • Wireless can be configured using several different signaling technologies such as: - Transceivers for delivering data through point-to-point or multipoint configuration over a range of 1 to 10 miles - Breaking a region into "cells", each cell has a radio transmitter/receiver • Other wireless signaling technologies: - Microwave technology uses microwave signaling and has the ability to be transmitted distances of 30 miles or more with significantly higher speeds - Infrared is a low-power wireless technology that is good for short distances, typically on an office floor - Laser uses a laser and optical system for short distances (like building to building) • Wireless LAN technologies are currently defined in the following IEEE standards: - 802.11a: Operates at 5.0 GHz and has a data rate of 54 Mbps - 802.11b: Operates at 2.4 GHz and has a data rate of 11 Mbps - 802.11g: Operates at 2.4 GHz and has a data rate of 54 Mbps • Bluetooth is an open standard that allows interoperation between equipment from different vendors and is aimed primarily at LAN devices and components - Home RF is one of the newest standards in RF wireless technology to help meet demands in the home networking arena