Point-to-multipoint Communication
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telecommunications Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than tha ...
, point-to-multipoint communication (P2MP, PTMP or PMP) is
communication Communication (from la, communicare, meaning "to share" or "to be in relation with") is usually defined as the transmission of information. The term may also refer to the message communicated through such transmissions or the field of inqu ...
which is accomplished via a distinct type of one-to-many connection, providing multiple paths from a single location to multiple locations. Point-to-multipoint
telecommunications Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than tha ...
is typically used in wireless Internet and IP telephony via
gigahertz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is sāˆ’1, meaning that one ...
radio frequencies. P2MP systems have been designed with and without a return channel from the multiple receivers. A central antenna or antenna array broadcasts to several receiving antennas and the system uses a form of time-division multiplexing to allow for the return channel traffic.


Modern point-to-multipoint links

In contemporary usage, the term point-to-multipoint wireless communications relates to fixed wireless data communications for Internet or voice over IP via
radio Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300  gigahertz (GHz). They are generated by an electronic device called a transm ...
or
microwave Microwave is a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter corresponding to frequency, frequencies between 300 MHz and 300 GHz respectively. Different sources define different fre ...
frequencies in the gigahertz range. Point-to-multipoint is the most popular approach for wireless communications that have a large number of nodes, end destinations or end users. Point to Multipoint generally assumes there is a central
base station Base station (or base radio station) is ā€“ according to the International Telecommunication Union's (ITU) Radio Regulations (RR) ā€“ a " land station in the land mobile service." The term is used in the context of mobile telephony, wireless c ...
to which remote ''subscriber units'' or customer premises equipment (CPE) (a term that was originally used in the wired telephone industry) are connected over the wireless medium. Connections between the ''base station'' and ''subscriber units'' can be either line-of-sight or, for lower-frequency radio systems, non-line-of-sight where link budgets permit. Generally, lower frequencies can offer non-line-of-sight connections. Various software planning tools can be used to determine feasibility of potential connections using topographic data as well as link budget simulation. Often the point to multipoint links are installed to reduce the cost of infrastructure and increase the number of CPE's and connectivity. Point-to-multipoint wireless networks employing directional antennas are affected by the hidden node problem (also called hidden terminal) in case they employ a CSMA/CA medium access control protocol. The negative impact of the hidden node problem can be mitigated using a time-division multiple access (TDMA) based protocol or a polling protocol rather than the CSMA/CA protocol. The
telecommunication Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than tha ...
s signal in a point-to-multipoint system is typically bi-directional, TDMA or channelized. Systems using frequency-division duplexing (FDD) offer full-duplex connections between base station and remote sites, and time-division duplex (TDD) systems offer half-duplex connections. Point-to-multipoint systems can be implemented in licensed, semi-licensed or unlicensed frequency bands depending on the specific application. point-to-point and point-to-multipoint links are very popular in the wireless industry and when paired with other high-capacity wireless links or technologies such as free space optics (FSO) can be referred to as backhaul. The base station may have a single omnidirectional antenna or multiple sector antennas, the latter of which allowing greater range and capacity.


See also

* Backhaul (telecommunications) *
Broadcasting (networking) In computer networking, telecommunication and information theory, broadcasting is a method of transferring a message to all recipients simultaneously. Broadcasting can be performed as a high-level operation in a program, for example, broadcas ...
* Local Multipoint Distribution Service * Multichannel Multipoint Distribution Service * Wireless access point


References

{{DEFAULTSORT:Point-To-Multipoint Communication Telecommunication services Wireless networking Network topology