Duplexing in Wireless Communication Systems
Duplexing methods are used in dividing forward and reverse communication channels in communication mediums. There are three major types of duplexing methods in wireless communication channels; Time Division duplexing (TDD) and Frequency Division Duplexing (FDD). Other duplexing methods can include Echo cancellation.
In FDD, systems can do simultaneous transmission and reception because the downlink (receive) frequencies are separate from the uplink (transmit) frequencies). FDD systems use filters for a radio with a receiver and transmitter to filter out noises from either receiver or transmitter. Guard bands are used to make the filters effective by separating downlink and uplink frequencies.
In FDD, systems can do simultaneous transmission and reception because the downlink (receive) frequencies are separate from the uplink (transmit) frequencies). FDD systems use filters for a radio with a receiver and transmitter to filter out noises from either receiver or transmitter. Guard bands are used to make the filters effective by separating downlink and uplink frequencies.
Use cases of FDD:
- Microwave links
- mmWave links
- Most 4G/LTE networks (some use TDD)
Check out these external filters that can be used in RF systems to allow or block certain frequencies in the system.
TDD systems cannot do simultaneous transmission and reception. In TDD, a certain time slot is set for RX for DL/receive and a certain time slot is reserved for UL/transmit. The system rapidly switches between transmit and receive. The systems in TDD can be asymmetrical as required to accommodate either more download or upload.
TDD also uses guard times to prevent overlap between downlinks and uplinks.
Use cases of TDD:
- Wi-Fi networks
- Some 4G/LTE networks
Check out these amplifiers that can be used in FDD and TDD systems.
Contact an Rfwel Engineering Wireless Specialist to learn more about RF equipment that you can use in your RF system implementation.
Related Articles
TV White Space Applied in Rural Broadband Wireless Communication
TV Whitespace (TVWS) radios are being deployed in rural communities by ISPs to provide broadband services. Radio wave propagation at 470 -698 MHz (United States) and 470 - 786 MHz (Global) favors NLOS communications. The 900 MHz, 2.4 GHz & 5 GHz and ...Newly opened up white-space spectrum to enable a plethora of new wireless application
The beauty of the spectrum between existing TV bands around 50MHz to 700MHz is indoor penetration possibility. The FCC in allowing the use of this spectrum for unlicensed devices also allocated two channels nationwide for wireless microphones who ...Fixed Wireless Access Developments
With Cellular operators pushing the reach of 5G mmWave, we could see the application of 5G even in rural areas as opposed to urban areas only. Due to its propagation characteristics, mmWave has been known for short signal reach hence only suitable ...The C-Band Spectrum
Spectrum, the medium on which wireless communication relies, is a very important resource, and a scarce one when it comes to 4G, 5G, and other wireless technologies like TVWS and Wi-Fi. Just recently, C-Band actioning saw about half a dozen companies ...FCC Subsidies for Rural broadband Internet Access
There are several programs and subsidies offered by the Federal Communications Commission (FCC ) to help improve rural broadband access. These include: Enhanced ACAM The Enhanced Alternative Connect America Cost Model was established by the Federal ...