Wireless Glossary – D

Digital to Analogue Converter is a device that converts a digital (usually binary) code to an analog signal (current, voltage, or electric charge).

OSI model, Layer 2. In transmitting across the network, this layer ensures reliable data transfer from the Network layer to the Physical layer.

Supported by IP and IPX protocols, the packet transports data across the internetwork.

A ratio of decibels to half wave dipole antenna, that is commonly used to measure antenna gain. (0 dBd = 2.15 dBi).

A ratio of decibels to an isotropic antenna that is commonly used to measure antenna gain. The greater the dBi value, the higher the gain and, as such, the more acute the angle of coverage.

Decibel referenced to a milli Watt

Dedicated Control CHannel is a single timeslot on an RF carrier that is used to convey eight Stand-alone Dedicated Control Channels (SDCCH). A single MS for call setup, authentication, location updating and SMS point to point use a SDCCH. As we will see later, SDCCH can also be found on a BCCH/CCCH timeslot, this configuration only allows four SDCCHs.

This term, also known as Data Communications Equipment, is used to describe a device that connects the Data Terminal Equipment (DTE) to a service provider’s communications line. Examples of DCE are modems, CSU/DSUs, and BRI NT-1s.

Downlink Control Information is used to describe the control signaling messages transmitted on the Physical Downlink Control CHannel.

Typically used for ISDN connections, this routing technology is used to enable network connections when needed and disable them after the need is fulfilled.

The service provider automatically marks Discard Eligible any traffic exceeding the CIR in a Frame Relay network. This marked traffic could be dropped in case of network congestion.

In electronics and communications, the decibel (abbreviated as dB, and also as db and DB) is a logarithmic expression of the ratio between two signal power, voltage, or current levels.

The point where the telco terminates its line to the customer.

Today considered to be fairly weak, DES was one of the first electronic encryption algorithms used. IBM first developed it to support a 56-bit key.

Received an undesired signal that was strong enough to make the module insensitive to the desired signal.

The switch with the lowest total cost to the root has the designated port, on each STP segment.

Dynamic Frequency Selection

Dynamic Host Configuration Protocol is a network protocol that is used to configure network devices so that they can communicate on an IP network. A DHCP client uses the DHCP protocol to acquire configuration information, such as an IP address, a default route and one or more DNS server addresses from a DHCP server. The DHCP client then uses this information to configure its host. Once the configuration process is complete, the host is able to communicate on the Internet.

Non-metallic and, therefore, non-conductive. Glass fibers are considered dielectric. A dielectric cable contains no metallic components.

Modulation technique used by IEEE 802.11-compliant wireless LANs for transmission at 1Mbps.

This asymmetric (public and private key) algorithm allows for a protected exchange of encryption keys over a public network.

Partial obstruction of a signal. Typically diffraction attenuates a signal so much that the link is unacceptable. However, in some instances where the obstruction is very close to the receiver, the link may be acceptable.

Differentiated Services is a computer networking architecture that specifies a simple, scalable and coarse-grained mechanism for classifying and managing network traffic and providing quality of service (QoS) on modern IP networks.

Differentiated Services, consistent with RFC 2474. A byte in the type of service (TOS) field of packets whose values correlates to the channel on which the packet should be sent. The value is a numeric code point. Motorola Canopy, for example, maps each of 64 code points to values of 0 through 7. Three of these code points have fixed values, and the remaining 61 are settable. Values of 0 through 3 map to the low-priority channel; 4 through 7 to the high-priority channel. The mappings are the same as 802.1p VLAN priorities. Among the settable parameters, the values are set in the AP for all downlinks within the sector and in the SM for each uplink.

DCF Interframe Space

Also known as a T1, this line provides 1.544 Mbps data transmission rate. A single T1 is composed of 24 digital signal level 0 (DS0) channels that are 64 Kbps each with an additional 8Kbps which is reserved for management overhead.

Used by OSPF and IS-IS, this routing algorithm constructs and calculates the shortest path to all known destinations.

Combines signals so only one coaxial wire needs to be run.

A type of low gain (2.2 dBi) antenna consisting of two (often internal) elements.

A straight electrical conductor measuring Ѕ wavelength from end to end and connected at the center to a radio-frequency feed line.

An antenna that concentrates transmission power into a direction thereby increasing coverage distance at the expense of coverage angle. Directional antenna types include yagi, patch and parabolic dish.

To turn off a feature in the module after both the feature activation file has activated the module to use the feature and the operator has enabled the feature in the module. See also Activate and Enable.

The cause of bandwidth limitations in a fiber. dispersion causes a broadening of input pulses along the length of the fiber. Three major types are: (1) modal dispersion caused by differential optical path lengths in a multimode fiber; (2) chromatic dispersion caused by a differential delay of various wavelengths of light in a waveguide material; and (3) waveguide dispersion caused by light traveling in both the core and cladding materials in single-mode fibers.

An industry-standard software technology for setting up and managing computing and data exchange in a system of distributed computers.

An intelligent system of two antennas that continually senses incoming radio signals and automatically selects the antenna best positioned to receive it.

A data link address utilized by Frame Relay.

A field in the data that the cmd show esn command generates from data in the SQL database in the Bandwidth and Authentication Manager (BAM) server. This field identifies the date of the most recent authentication attempt by the SM. Expressed in the database output as DLT.

DeModulation Reference Signal is embedded in the Physical Uplink Control CHannel (PUCCH) and Physical Uplink Shared CHannel (PUSCH) transmissions to provide the reference for demodulation of the PUCCH/PUSCH data.

Internet Protocol area outside of a firewall. Defined in RFC 2647.

An Application layer protocol that changes hostnames and fully qualified domain names, like www.winncom.com, into IP addresses.

Direction of Arrival denotes the direction from which usually a propagating wave arrives at a point, where usually a set of sensors are located. This set of sensors forms what is called a sensor array. Often there is the associated technique of beamforming which is estimating the signal from a given direction.

Controlled addition of small quantities of an impurity to a pure substance in order to change its characteristics, e.g. increase the refractive index (see refractive index) of the fiber core.

A type of attack that is enacted to deny a service that is usually available to a user or organization.

Downstream means a data stream from the central part of the network to the end user.

Chosen in OSPF to minimize routing update overhead that can take place in broadcast and nonbroadcast multiaccess topologies.

Dynamic Resource Allocation. The process of assigning resource blocks to different radio bearers in each subframe. This function is managed by the eNodeB.

Discontinuous Reception is a method used in mobile communication to conserve the battery of the mobile device. The mobile device and the network negotiate phases in which data transfer occurs. During other times the device turns its receiver off and enters a low power state.

DiffServe Code Point

Digital Signal Processor is a specialized microprocessor with an architecture optimized for the operational needs of digital signal processing.

Dedicated Traffic Channel is a logical channel used in LTE to deliver dedicated user data for a certain user equipment.

Devices like PCs, routers, and servers located at the user side of a network which are connected to the service provider via the DCE device.

Discontinuous Transmission is a means by which a mobile telephone is temporarily shut off or muted while the phone lacks a voice input.

EIGRP utilizes this algorithm to decide on the best loop-free path to a destination, and to determine alternative paths for certain conditions.

A network topology that employs two rings for the purpose of redundancy. If one ring experiences a failure, the other provides operability.

A device’s mode of communication which can be either half-duplex or full-duplex, depending on the connection type.

Downlink Pilot TimeSlot is a special downlink timeslot occurring in the 2nd (in some configurations the 7th) subframe of each radio frame when LTE is operated in TDD.

A dynamic Application layer protocol that functions to supply an IP address, subnet mask, domain name, and default gateway to network clients.

Automatically carries out NAT translations between two or more address pools.