Advantages and Disadvantages of Wireless OAM Multiplexing in 6G
This page covers advantages and disadvantages of OAM (Orbital Angular Momentum) in wireless communication (6G). It mentions benefits or advantages of OAM Multiplexing and drawbacks or disadvantages of Wireless OAM Multiplexing.
What is Wireless OAM Multiplexing?
Electromagnetic (EM) waves are charaterized by helical phase front in the direction of propagation. This charateristic is used in OAM to create multiple independent channels.
OAM is known as "Vortex EM wave" as it has phase rotation factor exp (-j*l*φ). Due to beam velocity and phase singularity characteristics of EM waves, it is possible to achieve unlimited OAM modes i.e. eigen states.
As OAM modes are orthogonal to each other, multiple channels are used to increase capacity as well as spectral efficiency.
OAM was initially used for optical communication. It has now been explored in microwave, mmwave and THz frequencies. OAM multiplexing find use in many applications such as deep space and near Earth optical communications, LAN to LAN connections in a campus or in city areas, wireless communication to carry EM waves in 6G technology and so on.
Benefits or advantages of OAM Multiplexing in wireless communication (6G)
Following are the benefits or advantages of OAM Multiplexing in wireless communication planned to be used in 6G technology.
➨It increases transmission rate in point-point links such as wireless backhaul and/or fronthaul.
➨EM wave multiplexing transmission has become possible due to OAM and this increases spectrum efficiency of future 6G (Sixth Generation) wireless networks.
➨OAM provides new access method called Mode Division Multiple Access. Hence it can support more number of users without use of more time/frequency resources.
➨It offers higher reliability for anti-jamming used in wireless communication.
➨OAM based MIMO system is suitable for long distance communication in open area.
Drawbacks or disadvantages of Wireless OAM Multiplexing
Following are the challenges or drawbacks or disadvantages of Wireless OAM Multiplexing:
➨Multiplexing and demultiplexing processes of radio frequency waves are complex to achieve.
➨Beam combining and splitting of OAM radio waves are difficult due to much longer wavelength than optical waves. Hence coaxial transmission is not easy to ensure.
➨To overcome above limitation, specialized devices are used which add insertion loss and reduces efficiency of the system.
➨Transmitter and receiver must have to be aligned with each other. This helps in separation of different OAM modes.
➨Wavefront phases of OAM beams are affected at the receiver due to fading such as rain, fog and atmospheric turbulence.
➨As the order of OAM mode increases, OAM beam becomes increasingly divergent. This reduces transmission distance severely. Moreover it decreases spectrum efficiency of OAM based wireless communication.
➨To identify different OAM modes and to demodulate the information modulated on eddy EM waves are key challenges.