A simplified decoding algorithm for multi-CRC polar codes

Polar codes represent one of the major breakthroughs in 5G standard,and have been proven to be able to achieve the symmetric capacity of binary-input discrete memoryless channels using the successive cancellation list(SCL)decoding algorithm.However,the SCL algorithm suffers from a large amount of memory overhead.This paper proposes an adaptive simplified decoding algorithm for multiple cyclic redundancy check(CRC)polar codes.Simulation results show that the proposed method can reduce the decoding complexity and memory space.It can also acquire the performance gain in the low signal to noise ratio region.

A UNIVERSAL ALGORITHM FOR PARALLEL CRC COMPUTATION AND ITS IMPLEMENTATION

Derived from a proposed universal mathematical expression, this paper investigates a novel algo-rithm for parallel Cyclic Redundancy Check (CRC) computation, which is an iterative algorithm to update the check-bit sequence step by step and suits to various argument selections of CRC computation. The algorithm proposed is quite suitable for hardware implementation. The simulation implementation and performance analysis suggest that it could efficiently speed up the computation compared with the conventional ones. The algorithm is implemented in hardware at as high as 21Gbps, and its usefulness in high-speed CRC computa-tions is implied, such as Asynchronous Transfer Mode (ATM) networks and 10G Ethernet.

CRC-AIDED TURBO EQUALIZATION FOR MIMO FREQUENCY SELECTIVE FADING CHANNELS

This paper presents a CRC (Cyclic Redundancy Check)-aided turbo equalization approach to reduce the computational complexity. In this approach,CRC code bits are padded to the end of each transmit block,and a cyclic redundancy check is performed after decoding each block at the receiver end. If the check sum is zero,which means the receive block is correct,the corresponding LLRs (Log Likelihood Ratios) of this block are set high reliable values,and all the computations corresponding to this block can be cancelled for the subsequent outer iterations. With a lower computational complexity the proposed approach can achieve the same as or even better performance than the conventional non-CRC method.

A MULTI-CRC SELECTIVE HARQ SCHEME FOR MIMO SYSTEMS

A multi-Cyclic Redundancy Check (CRC) selective Hybrid Automatic-Repeat-reQuest (HARQ) scheme for improving the throughput efficiency of Multiple Input Multiple Output (MIMO) systems is proposed in this paper. According to different feedback information from the receiver, the proposed HARQ scheme employs two strategies, referred to as retransmission frame selection and space diversity. These two strategies decrease the successive frame errors upon retransmission. Theoretic analysis and computer simulation results show that this HARQ scheme achieves higher throughput than the existing HARQ schemes even in poor conditions of low Signal-to-Noise Ratio (SNR).

Efficient Early Termination Strategy for LDPC Codes in GPS Systems

By exploiting the structural features of L1C messages,a novel Early Termination( ET) strategy is proposed to speed up the decoding of low-density parity-check( LDPC) codes in the GPS system. The proposed strategy is based on the cyclic redundancy check( CRC) of the messages in the subframes 2 and 3. The simulation results show that average number of iterations of the proposed strategy is less than that of the standard ET strategy,with nearly no degradation in decoding performance. Besides,the proposed ET strategy can be efficiently implemented in a sequential or parallel manner. Thus,the proposed ET strategy is attractive for practical purposes.

Optimal Data Transmission in Backscatter Communication for Passive Sensing Systems

Computational Radio Frequency IDentification (CRFID) is a device that integrates passive sensing and computing applications,which is powered by electromagnetic waves and read by the off-the-shelf Ultra High Frequency Radio Frequency IDentification (UHF RFID) readers.Traditional RFID only identifies the ID of the tag,and CRFID is different from traditional RFID.CRFID needs to transmit a large amount of sensing and computing data in the mobile sensing scene.However,the current Electronic Product Code,Class-1 Generation-2 (EPC C1G2)protocol mainly aims at the transmission of multi-tag and minor data.When a large amount of data need to be fed back,a more reliable communication mechanism must be used to ensure the efficiency of data exchange.The main strategy of this paper is to adjust the data frame length of the CRFID response dynamically to improve the efficiency and reliability of CRFID backscattering communication according to energy acquisition and channel complexity.This is done by constructing a dynamic data frame length model and optimizing the command set of the interface protocol.Then,according to the actual situation of the uplink,a dynamic data validation method is designed,which reduces the data transmission delay and the probability of retransmitting,and improves the throughput.The simulation results show that the proposed scheme is superior to the existing methods.Under different energy harvesting and channel conditions,the dynamic data frame length and verification method can approach the theoretical optimum.