The multi-band process is done after the OFDM process above is complete. OFDM symbols are interleaved in time across multiple frequencies, based on one of two types of Time-Frequency Codes (TFCs); (1) a Time-Frequency Interleaving (TFI) code where information is interleaved over three bands, or (2) Fixed Frequency Interleaving (FFI) which allows transmission of coded data on a single band. As time progresses the OFDM symbols are transmitted on different bands: symbol 1 is transmitted on band 1, symbol 2 on band 3 and symbol 3 on band 1. [Hel08]
Multi Band OFDM Interleaving Diagram courtesy of “A MB-OFDM System Implemented in Matlab”, Revision 1.1, by Helena Sarmento, 19 July 2008
Mega bits per second. 1,000,000 bits per second. [Arr11] MC Multipoint Controller
MCU Multipoint Conferencing Unit
MD5 Message Digest 5
MDS An abbreviation for Multipoint Distribution Service, a band of frequencies in the United States allocated for wireless television broadcast service. [Arr11]
The average power for a continuous valid symbol sequence coupled into a fiber. [Fib111] Mean Time to Repair (MTTR)
In cable television systems, the MTTR is the average elapsed time from the moment a loss of radio frequency (RF) channel operation is detected up to the moment the RF channel operation is fully restored.
A fiber splice accomplished by fixtures or materials, rather than by thermal fusion. Index matching material may be applied between the two fiber ends. [Arr11] Media Access Control Address (MAC-Address)
The unique hardware number assigned to network connection devices such as your computer's network card. In Ethernet, it is written as a series of six pairs of characters divided by hyphens (e.g., 00-0F-3D-50-A1-98), and is also referred to as the hardware address or adapter address. Or the “built-in” hardware address of a device connected to a shared medium. Media Access Control or Medium Access Control (MAC)
The MAC sublayer is the part of the data link layer that supports topology- dependent functions and uses the services of the Physical Layer to provide services to the Logical Link Control (LLC) sublayer. Or a component of a networking software stack. In the OSI 7-layer model, the Media Access Control is a part of layer 2, the data link layer.
Media Access Control Procedure (MAC-Procedure)
In a subnetwork, that part of the protocol that governs access to the transmission medium independent of the physical characteristics of the medium, but taking into account the topological aspects of the subnetworks, in order to enable the data exchange between nodes. MAC procedures include framing, error protection, and acquiring the right to use the underlying transmission medium.
Media Access Control Service Access Point (MSAP)
The conceptual binding of a media access control (MAC) layer service provider to the protocol entities (i.e., data link layers) above it.
Media Access Control Sublayer (MAC-Sublayer)
The part of the datalink layer that supports topology dependent functions and uses the services of the physical layer to provide services to the logical link control (LLC) sublayer.
Media Center Edition (MCE)
Microsoft's operating system optimized for the presentation and distribution of digital media content (video, audio, images, etc.).
Media Center Extender (MCX)
Microsoft's satellite media presentation device. Any device licensed by Microsoft to connect to a media center edition (MCE) to obtain and present Windows Media Digital Rights Management (WMDRM) protected digital media content.
Media Gateway (MG)
A MG terminates switched circuit network (SCN) facilities (trunks, loops), packetizes the media stream, if it is not already packetized, and delivers packetized traffic to the packet network. It performs these functions in the reverse order for media streams flowing from the packet network to the SCN.
Media Gateway Control Protocol (MGCP)
Protocol follow-on to SGCP. Refer to IETF RFC 2705.
Media Gateway Controller (MGC)
An MGC is the overall controller function of the public switched telephone network (PSTN) gateway. It receives and mediates call-signaling information between the PacketCable™ and the PSTN domains, and it maintains and controls the overall call state for all calls.
Satellite generating transmit power levels ranging from 30 to 100 watts. [Sat07] Mega
A prefix for one million (1,000,000 or 106 ). [Arr11] Megabit (Mb)
One million bits. Megabyte (MB)
A megabyte is 2 to the 20th power (220), or 1,048,576 bytes. It can be estimated as 10 to the 6th power, or one million (1,000,000) bytes. A megabyte is 1,024 kilobytes and precedes the gigabyte unit of measurement. Large computer files are typically measured in megabytes. For example, a high-quality JPEG photo from a 6.3 megapixel digital camera takes up about 3MB of space. A four minute CD-quality audio clip takes up about 40MB of space and CDs can hold up to 700MB of space. For a list of all the different units of measurements, view this Help Center article. Abbreviation: MB. [Tec11] MegaHertz (MHz)
One million cycles per second. MEMS
Micro-Electrical Mechanical Systems [IEC06] MEMS-Based VOA
Micro-Electrical Mechanical Systems (MEMS) based variable optical attenuator; uses tuned components that can be adjusted, typically by raising or lowering them, to accomplish attenuation by partially or completely blocking a stream of light. These components can be thought of as being very similar to a mechanized camera shutter, albeit on a much smaller scale. Multiple actuators can be used to provide a very highly resolved range of attenuation; this arrangement is potentially superior to alternative optical attenuation technologies. The diagram below illustrates a MEMS-based VOA. The cylindrical items are two optical fibers; attenuation is achieved by raising a metallic shutter in the gap. As they are significantly smaller and less power hungry than competing technologies, MEMS-based devices do not require temperature compensation, which affords several advantages. Temperature control requires additional electronics, which adds cost, complexity, power consumption, and real estate requirements to the component. Temperature control requirements also typically prevent non-MEMS-based VOA components from being deployed outside the central office (CO) or other controlled, telecommunications-oriented environment. MEMS-based VOA components can be deployed in a wider variety of environments, including outside plant and access networks. Potential applications for MEMS-based components in distribution environments include amplifiers for cable television systems and gain control devices for active FTTX deployments. [IEC06]
MEMS-based VOA Diagram courtesy of D. Horsley, "Image Gallery", http://mae.ucdavis.edu/faculty/horsley/photoalbum.html