Point-to-Multipoint Communication

In its simplest definition, point-to-multipoint communication is a distinct type of one-to-many connection where multiple paths from a single location open to multiple locations. It is abbreviated as P2MP, PTMP or PMP.

This type of connection is commonly used in telecommunications, IP telephony and wireless internet. It enables private enterprises to establish connectivity to offices in remote locations and provide long-range wireless backhaul solutions for different sites.

IP telephony is a term used on technologies that employ the Internet Protocol’s packet-switched connections to exchange fax, voice and other data that was previously carried over through PSTN (public switched telephone network). The term has also become synonymous to VoIP, although VoIP is often associated with actual services offered by many network providers.

Point to Multi-Point

Point-to-Multipoint Topology consists of a central base station that supports other subscriber stations. It has a bridge known as the base station bridge or root bridge, where all data that passes between the wireless bridge clients initially go through. The entire topology uses the same network resources from a single location, which are then shared among multiple locations.

In a broadcast connectivity, PTMP sends information from one uplink to multiple downlinks. In this setup, remote sites are limited to the receive-only mode, so there is only one transmission between the uplink and downlink. Should there be a need to add receive-only sites, it can be done without affecting the size of the uplink.

In the case of point-to-multipoint bridging, one access point talks directly to other access points, with each one also serving as another access point within a network.

A P2MP link, on the other hand, is a type of multipoint link that consists of a central connection endpoint (main point) and multiple peripheral remotes. Data transmitted from the main point is received by all the peripheral remotes, but data coming from a peripheral remote is only received by the central connection endpoint, not by other peripheral remotes.

A PTMP system is designed as both single and bidirectional. It consists of a central antenna or an array of antennas that broadcast to several receiving antennas. It uses a form of time division multiplexing that allows several users to share the same frequency channel. Because the signal is divided into different time slots, transmission can be done in rapid succession, while using only a part of a channel’s capacity.

Point-to-point vs. Point-to-multipoint

Differentiating between these two types of communications is as easy as understanding the labels. But for illustration purposes, take for example a WAN connection. If connectivity is only shared between two offices in different cities, WAN is transmitting point to point. There’s only one sender and one receiver.

If, however, a WAN connection is broadcasting to multiple receivers or destinations, it is transmitting from one point to multiple points.

Advantage and Disadvantage of Point-to-Multipoint Communication

Easily Deployed

When adding a receiver site in a PMP network, the needed equipment only needs to be deployed to the subscriber’s location, and the system is set up and expanded. It is vital to note, however, that remote sites must be within visibility and range of a base station.

Lack of Interconnectivity

In the case of a PMP node technology, nodes cannot interact with other nodes due to the directional antenna. The interaction of peripheral remotes in a PTMP link is also limited to the Main Point but never among remotes.