Channel Coding Algorithms For Uplink NB-IoT Systems

Internet of things(IoT)systems are one of the fast-growing communication technology in recent years that can enable the massive connectivity of consumer electronic devices including smart sensors,actuators,Bluetooth,radio frequency identification(RFID)tags,ZigBee,and smart devices which are accessible to the internet for transforming ideas and working systems.It is expected that in the near 2030s,massive IoT exposed to a massive number of devices within a distributed objects or things will be connected to the wireless network through a common addressing scheme,which brings in the evolution of new intelligent service systems available around the globe.Besides,different existing and emerging wireless communication technologies are suffering a lot of challenges to realize the objective of loT communications,including enhanced network coverage,low data rates,high complexity,and long delay sensitivity.In recent years,different IoT standardization bodies have proposed different technologies to accommodate such requirements of loT applications in current cellular networks.Specifically,a new cellular-based low power wide-area(LPWA)IoT technology known as the narrowband loT(NB-loT)systems has been standardized by the 3rd Generation Partnership Project(3GPP)as part of release-13,release 14,and recently in release 15 to serve some portion of fifth-generation(5G)technology.This dissertation addresses the main crucial aspects of Physical(PHY)layer channel coding in uplink NB-IoT systems.In uplink NB-IoT systems,various channel coding algorithms are deployed due to the nature of adopted Long Term Evolution(LTE)channel coding presents a great challenge at the expense of high decoding complexity,power consumption,error floor phenomenon,and at the same time experience performance degradation for short block length.For this reason,such a design will greatly increase the complexity of the system,which is difficult to implement.Therefore,the existing LTE turbo codes will not be recommended in NB-IoT systems and hence,new channel coding algorithms need to be employed for LPWA specifications.Firstly,the LTE-based Turbo decoding and frequency-domain Turbo equalization algorithms are proposed,modifying the simplified Maximum a posteriori probability(MAP)decoder and a minimum mean square error(MMSE)Turbo equalization algorithms which are appended to different Narrowband Physical Uplink Shared Channel(NPUSCH)subcarriers for interference cancellation.These proposed methods aim to minimize the complexity of realizing the traditional MAP Turbo decoder and MMSE estimators in the newly NB-IoT PHY layer features.Then,we compare the system performance in terms of block error probability(BLER)and computational complexity.Secondly,to minimize decoding complexity,we proposed an efficient Cyclic Redundancy Check(CRC)aided Successive Cancellation List(CA-SCL)Polar decoding algorithm for uplink in NB-IoT systems.This approach utilizes the reduced complexity SCL Polar decoding algorithm due to its excellent error-correcting performance and its advantages of low decoding complexity over the conventional Polar decoding scheme.However,we further incorporate the SCL scheme with the CRC termination loop to minimize the decoding iteration,then the log-likelihood ratio(LLR)values of the SCL decoder node are updated iteratively,then,simulation results demonstrate that the proposed algorithm can significantly improve error rate performance through the BLER and number of decoding iteration especially at a low signal-to-noise ratio(SNR)which is best suited for LPWA technology of NB-IoT systems.Thirdly,we proposed an efficient polar coding technique using the Belief Propagation(BP)decoding algorithm for uplink data transmission on the NPUSCH channel.Furthermore,the BP algorithm is incorporated with the CRC stoppage criterion to decrease the number of decoding iteration and reduce computational complexity.In this scheme,single-tone numerology of NPUSCH using 3.75 kHz and 15 kHz subcarrier spacing is adopted.Then,the encoded data is generated with different NPUSCH resources.The theoretical formulation and simulation demonstrate that the proposed scheme provides better error rate performance over the adopted LTE turbo codes and other polar decoding algorithms while reducing the computational complexity.Finally,we proposed an efficient FPGA implementation of simplified Fast Polar codes based on the CA-FSCL decoding algorithm.As compared with the conventional SCL Polar decoder,the FSCL generates candidate paths,which results in more resource costs and higher decoding latency.To minimize this drawback,we employed the odd-even sorter(OES).Then,we eliminate the candidate paths that are not part of the L best paths by the proposed lossless pruning algorithm.Finally,a compatible sorting network combining the advantages of a half-clear(HC)network and pruned rear network(PRN)is proposed.The corresponding CA-FSCL decoder architecture is described using a very-high-speed integrated circuit Hardware description language(VHDL)which is synthesized on the Xilinx VC-7809 FPGA tool.Extensive simulation and implementations demonstrate that the proposed method achieves significant gain in hardware consumptions,especially for large list sizes and block lengths.