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The history of modems is the attempt at increasing the bit rate over a fixed bandwidth (and therefore a fixed maximum symbol rate), leading to increasing bits per symbol. For example, ITU-T V.29 specifies 4 bits per symbol, at a symbol rate of 2,400 baud, giving an effective bit rate of 9,600 bits per second.
The BER is the likelihood of a bit misinterpretation due to electrical noise ().Considering a bipolar NRZ transmission, we have = + for a "1" and () = + for a "0".Each of () and () has a period of .
As the description implies, is the signal energy associated with each user data bit; it is equal to the signal power divided by the user bit rate (not the channel symbol rate). If signal power is in watts and bit rate is in bits per second, E b {\displaystyle E_{b}} is in units of joules (watt-seconds).
When UI is used as a measurement unit of a time interval, the resulting measure of such time interval is dimensionless. It expresses the time interval in terms of UI. Very often, but not always, the UI coincides with the bit time, i.e. with the time interval taken to transmit one bit (binary information digit).
The symbol duration time, also known as the unit interval, can be directly measured as the time between transitions by looking at an eye diagram of the signal on an oscilloscope. The symbol duration time T s can be calculated as: =, where f s is the symbol rate. There is also a chance of miscommunication which leads to ambiguity.
For example, the sample diagram does not indicate the physical type of connection between the PCs and the switch, but since a modern LAN is depicted, Ethernet may be assumed. If the same style of line was used in a WAN (wide area network) diagram, however, it may indicate a different type of connection.
The standard symbol guard interval used in IEEE 802.11 OFDM is 0.8 μs. To increase data rate, 802.11n added optional support for a 0.4 μs guard interval. This provides an 11% increase in data rate. To increase coverage area, IEEE 802.11ax (Wi-Fi 6) provides optional support for 0.8 μs, 1.6 μs, and 3.2 μs guard intervals. [citation needed]
In computer networking, a routing table, or routing information base (RIB), is a data table stored in a router or a network host that lists the routes to particular network destinations, and in some cases, metrics (distances) associated with those routes. The routing table contains information about the topology of the network immediately ...