A Transceiver Design for Spectrum Sharing in Mixed Numerology Environments

A Transceiver Design for Spectrum Sharing in Mixed Numerology Environments

Abstract: We consider a mixed numerology spectrum sharing (SS) system where the users have different subcarrier spacing (SCS). Unlike in single numerology SS systems, mixed numerology SS systems suffer from inter-numerology interference (INI).

We first derive the interference pattern and find that the variance of interference energy increases due to the difference in SCS. This increase in variance negatively affects decoding performance, since the interference energy is unbalanced between subcarriers. However, previous works on this issue did not take this interference pattern into account for interference management. In order to suppress the increase in variance of the interference energy, we propose a transceiver structure for large SCS users by using simple cyclic shift and frequency shift operations. The proposed transceiver disperses the effect of INI, reducing the variance in the interference energy. From the derived distribution characteristics of the interference energy in closed-form expressions, we show that the proposed transceiver achieves better decoding performance.

Existing system:

The interference pattern is different between mixed and single numerology SS systems due to mismatch in receiving window length, and this results in internumerology interference Hence, existing interference management techniques considering single numerology SS systems may not be sufficient to satisfy system requirements. Moreover, unlike non-overlapping mixed numerology systems, different numerologies are combined in the same time and frequency resource in mixed numerology SS systems, making it impossible to avoid interference by using windowing, filtering, and guard interval/band techniques. The research to date on mixed numerology systems with SS has focused on symbol design.

Proposed system: However, combining multiple numerologies in one frequency Band has the potential to destroy orthogonality, resulting in an out-of-band-emission (OOBE) problem. Several works have analyzed the pattern of emitted interference. In order to combat the OOBE problem, a number of studies have been conducted.

Waveform designs have been proposed based on sub band-filtered multi-carrier systems, such as filtered OFDM, filter bank multi-carrier, and discrete Fourier transform spread OFDM systems. It has been shown that inserting a guard interval or guard band is also an effective solution. In addition, optimizing the number of active numerologies and interference cancellation techniques has been studied as a way to combat the OOBE problem Advantages: Non-overlapping mixed numerology systems offer some advantages in interference management. For example, in mixed numerology systems with TDM, orthogonality is maintained between the consecutive blocks with the help of the orthogonal frequency division multiplexing (OFDM) waveform design.

Mixed numerology systems with FDM have advantages in forward compatibility and their ability to support various latency requirements.

Disadvantages: However, combining multiple numerologies in one frequency band has the potential to destroy orthogonality, resulting in an out-of-band-emission (OOBE) problem.

Several works have analyzed the pattern of emitted interference, In order to combat the OOBE problem, a number of studies have been conducted. Waveform designs have been proposed based on sub band-filtered multi-carrier systems, such as filtered OFDM, filter bank multi-carrier, and discrete Fourier transform spread OFDM systems.

Modules: Enhanced mobile broadband: Upcoming cellular systems will require more flexible resource distribution to support a variety of applications with diverse requirements. Wireless standards accordingly have considered the coexistence of multiple communication scenarios such as enhanced mobile broadband (eMBB), massive machine type communication (mMTC), and ultra-reliable and low latency communication (URLLC). Conventional resource distribution adopts a single numerology with uniform frame design. Since future cellular systems will have to consider a variety of scenarios, it is impossible to design an all-encompassing numerology that satisfies every service requirement.

Time domain: One is the non-overlapping mixed numerology system with Multiplexing in the time domain (TDM) or in the frequency domain (FDM) between numerologies.

The other is the overlapping mixed numerology system with spectrum sharing (SS). Non-overlapping mixed numerology systems offer some advantages in interference management. For example, in mixed numerology systems with TDM, orthogonality is maintained between the consecutive blocks with the help of the orthogonal frequency division multiplexing (OFDM) waveform design. Mixed numerology systems with FDM have advantages in forward compatibility and their ability to support various latency requirements.

Out – of – band – emission: However, combining multiple numerologies in one frequency band has the potential to destroy orthogonality, resulting in an out-of-band-emission (OOBE) problem. Several works have analyzed the pattern of emitted interference. In order to combat the OOBE problem, a number of studies have been conducted.

Waveform designs have been proposed based on sub band-filtered multi-carrier systems, such as filtered OFDM, filter bank multi-carrier, and discrete Fourier transform spread OFDM systems. It has been shown that inserting a guard interval or guard band is also an effective solution. In addition, optimizing the number of active numerologies and interference cancellation techniques has been studied as a way to combat the OOBE problem.

Numerology system: The interference pattern is different between mixed and single numerology SS systems due to mismatch in receiving window length, and this results in internumerology interference. Hence, existing interference management techniques considering single numerology SS systems may not be sufficient to satisfy system requirements. Moreover, unlike non-overlapping mixed numerology systems, different numerologies are combined in the same time and frequency resource in fixed numerology SS systems, making it impossible to avoid interference by using windowing, filtering, and guard interval/band techniques. The research to date on mixed numerology systems with SS has focused on symbol design.