Fixed Radio Links

Fixed radio links are an important communication technology used to provide high-speed and reliable communication between two points. These links are often used to provide connectivity to remote locations, connect buildings within a campus or provide backhaul for cellular networks. In this article, we will discuss fixed radio links in detail, including their technology, components, types, and applications.

Fixed Radio Links – An Overview

A fixed radio link is a communication link that uses a fixed antenna to transmit and receive data between two points. The link is fixed in the sense that the two antennas are aligned to each other and do not move. The antennas can be placed on top of buildings, masts, towers, or any other suitable structure. The link operates in the radio frequency spectrum and is capable of providing high-speed data transfer rates ranging from a few Mbps to several Gbps.

Fixed radio links are often used as a last-mile solution to provide connectivity to remote areas where it is not feasible to lay fiber cables. The links can also be used to provide backhaul for cellular networks, connecting base stations to the core network. In addition, fixed radio links are used to connect buildings within a campus, providing high-speed data transfer between different departments or floors.

Fixed radio links are also used in disaster management situations to provide communication links between disaster-affected areas and the outside world. The links are often used as a backup solution for primary communication links such as fiber cables, which can be damaged or disrupted during natural calamities.

Fixed Radio Link Components

Fixed radio links consist of several components that work together to provide high-speed and reliable communication. These components include the following:

1. Antennas: Antennas are the most important component of a fixed radio link. They are used to transmit and receive data between the two points. The antennas are designed to operate in a specific frequency band, and their gain and beamwidth determine the coverage area and range of the link.
2. Radio Equipment: The radio equipment is used to modulate and demodulate the data that is transmitted over the link. It is responsible for encoding the data into a format that can be transmitted over the radio link and decoding it at the receiving end.
3. Transmitter: The transmitter is used to amplify and transmit the data over the radio link. It is responsible for converting the data into radio signals that can be transmitted over the air.
4. Receiver: The receiver is used to receive the radio signals that are transmitted over the air. It is responsible for demodulating the data and converting it into a format that can be used by the radio equipment.
5. Power Supply: The power supply is used to provide power to the radio equipment, transmitter, and receiver.

Fixed Radio Link Types

Fixed radio links can be classified into several types based on their frequency band, modulation technique, and range. Some of the commonly used types of fixed radio links are as follows:

1. Microwave Links: Microwave links operate in the frequency range of 1 GHz to 100 GHz. They are used for long-range communication and can provide data transfer rates ranging from a few Mbps to several Gbps. Microwave links are often used to provide backhaul for cellular networks and connect remote locations.
2. Millimeter Wave Links: Millimeter wave links operate in the frequency range of 30 GHz to 300 GHz. They are used for short-range communication and can provide data transfer rates ranging from a few Gbps to several tens of Gbps. Millimeter wave links are often used for high-speed data transfer between buildings within a campus or in a metropolitan area.
3. Radio over Fiber Links: Radio over fiber links use optical fibers to transmit and receive radio signals. They are used for long-range communication and can provide data transfer rates ranging from a few Mbps to several Gbps. Radio over fiber links are often used to provide backhaul for cellular networks and connect remote locations where laying fiber cables is not feasible.
4. Free Space Optics Links: Free Space Optics (FSO) links use laser beams to transmit and receive data over the air. They operate in the infrared spectrum and can provide data transfer rates ranging from a few Mbps to several Gbps. FSO links are often used for short-range communication between buildings within a campus or in a metropolitan area.
5. Near Line of Sight Links: Near Line of Sight (nLOS) links are used to provide communication between two points where there is partial obstruction in the line of sight. They operate in the frequency range of 5 GHz to 38 GHz and can provide data transfer rates ranging from a few Mbps to several Gbps.
6. Non-Line of Sight Links: Non-Line of Sight (NLOS) links are used to provide communication between two points where there is no direct line of sight. They operate in the frequency range of 2.4 GHz to 5.8 GHz and can provide data transfer rates ranging from a few Mbps to several Gbps. NLOS links are often used to provide communication in urban areas where there are tall buildings that obstruct the line of sight.

Fixed Radio Link Technology

Fixed radio links use various technologies to ensure high-speed and reliable communication. These technologies include the following:

1. Frequency Division Multiplexing (FDM): FDM is a technology that allows multiple signals to be transmitted over a single communication channel. In a fixed radio link, FDM is used to divide the frequency band into multiple channels, each carrying a separate data signal.
2. Time Division Multiplexing (TDM): TDM is a technology that allows multiple signals to be transmitted over a single communication channel by dividing the channel into time slots. In a fixed radio link, TDM is used to divide the channel into time slots, with each slot carrying a separate data signal.
3. Orthogonal Frequency Division Multiplexing (OFDM): OFDM is a technology that uses multiple sub-carriers to transmit data over a communication channel. In a fixed radio link, OFDM is used to increase the data transfer rate and improve the link reliability by using multiple sub-carriers.
4. Multiple Input Multiple Output (MIMO): MIMO is a technology that uses multiple antennas to improve the link performance. In a fixed radio link, MIMO is used to increase the data transfer rate and improve the link reliability by using multiple antennas at both the transmitter and receiver ends.
5. Adaptive Modulation: Adaptive modulation is a technology that adjusts the modulation scheme based on the link conditions. In a fixed radio link, adaptive modulation is used to adjust the modulation scheme based on the signal strength and interference to ensure reliable communication.

Fixed Radio Link Applications

Fixed radio links are used in various applications, including the following:

1. Last-Mile Connectivity: Fixed radio links are often used to provide last-mile connectivity to remote locations where laying fiber cables is not feasible. The links can provide high-speed and reliable communication to these locations, allowing businesses and individuals to access the internet and other network resources.
2. Backhaul for Cellular Networks: Fixed radio links are often used to provide backhaul for cellular networks, connecting base stations to the core network. The links can provide high-speed and reliable communication, ensuring that the cellular network operates efficiently.
3. Campus Connectivity: Fixed radio links are used to provide high-speed connectivity between buildings within a campus. The links can provide high-speed data transfer between different departments or floors, allowing students, faculty, and staff to access network resources.
4. Disaster Management: Fixed radio links are often used in disaster management situations to provide communication links between disaster-affected areas and the outside world.