Nima Azadi-Tinat, Mohsen Koohestani
Received: 2024-07-14; Revised: 2024-08-30; Accepted: 2024-09-25; Online: 2024-10-29
This paper presents a novel approach to design a compact circular rat-race coupler with an ultrawide stopband, with the aim to reduce its size while maintaining performance. The design methodology begins with a common miniaturization technique to replace the conventional quarter-wavelength transmission line with an equivalent low-pass filter loaded with parallel coupled line and radial stubs. Since the latter leads to produce higher order harmonics, parasitic open-ended stubs are then properly introduced in the structure not only to overcome the issue but also to produce controllable transmission zeros. A versatile analytical model is also developed taking into account manufacturing restrictions, which makes it possible to extract the physical parameters of the coupler unit-cell for a given desired compactness percentage with respect to the conventional rat-race coupler. A prototype is fabricated and measured to validate the design, demonstrating the predicted behavior fairly achieved by numerical analysis. A significant size reduction of about 86.1% was achieved compared to the conventional design, while effectively suppressing higher order modes up to 23.4 GHz (including the 13th harmonic based on |S11|>?5 dB and |S21|
Low Complexity Successive Cancellation List Decoding of U-UV Codes
Wenhao Chen, Li Chen, Jingyu Lin, Huazi Zhang
Received: 2024-01-19; Revised: 2024-08-21; Accepted: 2024-09-11; Online: 2024-10-29
Constituted by BCH component codes and its ordered statistics decoding (OSD), the successive cancellation list (SCL) decoding of U-UV structural codes can provide competent error-correction performance in the short-to-medium length regime. However, this list decoding complexity becomes formidable as the decoding output list size increases. This is primarily incurred by the OSD. Addressing this challenge, this paper proposes the low complexity SCL decoding through reducing the complexity of component code decoding, and pruning the redundant SCL decoding paths. For the former, an efficient skipping rule is introduced for the OSD so that the higher order decoding can be skipped when they are not possible to provide a more likely codeword candidate. It is further extended to the OSD variant, the box-andmatch algorithm (BMA), in facilitating the component code decoding. Moreover, through estimating the correlation distance lower bounds (CDLBs) of the component code decoding outputs, a path pruning (PP)-SCL decoding is proposed to further facilitate the decoding of U-UV codes. In particular, its integration with the improved OSD and BMA is discussed. Simulation results show that significant complexity reduction can be achieved. Consequently, the U-UV codes can outperform the cyclic redundancy check (CRC)-polar codes with a similar decoding complexity.