[2] The non-standard abbreviation bps is often used to replace the standard symbol bit/s, so that, for example, 1 Mbps is used to mean one million bits per second.
[4][5] The International Standard (IEC 80000-13) specifies different symbols for binary and decimal (SI) prefixes (e.g., 1 KiB/s = 1024 B/s = 8192 bit/s, and 1 MiB/s = 1024 KiB/s).
In digital communication systems, the physical layer gross bitrate,[6] raw bitrate,[7] data signaling rate,[8] gross data transfer rate[9] or uncoded transmission rate[7] (sometimes written as a variable Rb[6][7] or fb[10]) is the total number of physically transferred bits per second over a communication link, including useful data as well as protocol overhead.
However, the gross bit rate and the baud value are equal only when there are only two levels per symbol, representing 0 and 1, meaning that each symbol of a data transmission system carries exactly one bit of data; for example, this is not the case for modern modulation systems used in modems and LAN equipment.
Most other digital carrier-modulated schemes, for example ASK, PSK, QAM and OFDM, can be characterized as double sideband modulation, resulting in the following relation: In case of parallel communication, the gross bit rate is given by where n is the number of parallel channels, Mi is the number of symbols or levels of the modulation in the ith channel, and Ti is the symbol duration time, expressed in seconds, for the ith channel.
Error-correcting codes are common especially in wireless communication systems, broadband modem standards and modern copper-based high-speed LANs.
The connection speed of a technology that involves forward error correction typically refers to the physical layer net bit rate in accordance with the above definition.
The "connection speed" of a V.92 voiceband modem typically refers to the gross bit rate, since there is no additional error-correction code.
The channel capacity, also known as the Shannon capacity, is a theoretical upper bound for the maximum net bitrate, exclusive of forward error correction coding, that is possible without bit errors for a certain physical analog node-to-node communication link.
The term throughput, essentially the same thing as digital bandwidth consumption, denotes the achieved average useful bit rate in a computer network over a logical or physical communication link or through a network node, typically measured at a reference point above the data link layer.
These are examples of physical layer net bit rates in proposed communication standard interfaces and devices: In digital multimedia, bit rate represents the amount of information, or detail, that is stored per unit of time of a recording.
The encoding bit rate of a multimedia file is its size in bytes divided by the playback time of the recording (in seconds), multiplied by eight.
For real-time streaming multimedia, the encoding bit rate is the goodput that is required to avoid playback interruption.
Compact Disc Digital Audio (CD-DA) uses 44,100 samples per second, each with a bit depth of 16, a format sometimes abbreviated like "16bit / 44.1kHz".
Audio quality improves with increasing bitrate: For technical reasons (hardware/software protocols, overheads, encoding schemes, etc.)
For example, telephone circuits using μlaw or A-law companding (pulse code modulation) yield 64 kbit/s.