Physical Uplink Shared Channel Research Articles

An optimization NPUSCH uplink scheduling approach for NB-IoT application via the feasible combinations of link adaptation, Resource assignment and energy efficiency

Low-power wide area (LPWA) technology, specifically Narrowband Internet of Things (NB-IoT), has emerged as a pivotal sixth-generation (6G) network technology, catering to the demands of massive-type communications (m-MTC), extended battery life, wide range coverage, and high reliability. Despite its advancements, existing studies often fall short in simultaneously addressing energy efficiency, latency, link adaptation, and resource allocation in the bandwidth-constrained environments typical of NB-IoT. The complexity of finding a comprehensive optimal solution for resource allocation is compounded by its non-convex and NP-hard combinatorial nature. This research addresses these challenges by introducing a Hybrid-Optimizer approach, which integrates link adaptation, resource allocation, and scheduling algorithms. This approach aims to identify the optimal feasible combination for each device (UE), focusing on energy conservation and improved signal reception. Applied to the Narrow Physical Uplink Shared Channel (NPUSCH) uplink scheduling in NB-IoT, this method is benchmarked against the conventional Round-Robin scheduling algorithm. Simulation results demonstrate that the Hybrid-Optimizer approach significantly outperforms the Round-Robin algorithm in terms of scheduling processing time and energy efficiency. Furthermore, the proposed algorithm is capable of generating candidate combinations that enhance signal reception in UEs and meet the required subframe criteria, adhering to system modeling assumptions for scheduling optimization.

A Review of the 3GPP-Compatible Model of 5G in-Band Emissions in Uplink Resource Allocation in Hybrid Network

In-band emission represents a critical metric for assessing the reliability of a mobile communication network and ensuring quality of service (QoS) for end users. In the 5G network deployment, due to the limited availability of frequency spectrum, mobile users and internet-of-things (IoT) devices will transmit on the same frequency bands, necessitating more stringent in-band interference management to facilitate interference-free communication. In order to ensure that high-power user equipment (UEs) accessing the shared 5G uplink channel are able to communicate without disruption and without interfering with low-power devices, it is imperative to undertake in-band emissions analysis and control. This paper explores the issue of in-band emission interference, which pertains to the interference that arises in unallocated sub-bands within a specific bandwidth. Specifically, this investigation delves into the modeling approach and regulated in-band emissions within a non-standalone (NSA) 5G network. To verify compliance with 3GPP requirements for in-band emissions regulations, an over-the-air (OTA) testing system is employed to examine in-band emissions in the physical uplink shared channel (PUSCH). The study employs various resource block distributions, offsets, and modulation techniques within the specified NR channel bandwidth. All simulations are based on 3GPP specifications.

A Resource Optimization for Two-Step Random Access in 5G New Radio

This paper presents a resource optimization method for the 2-step random access (RA) procedure in the 5th generation new radio (5G NR). In 2-step RA, the MsgA includes a sequence as a preamble on the physical random access channel (PRACH) and uplink payload on the physical uplink shared channel (PUSCH). The mapping between PRACH slots and PUSCH slots is specified by system configuration parameters. The network reserves the corresponding PUSCH resource fixedly, regardless of the random access occasion (RO) occupancy rate and the uplink data traffic request. It deprives the uplink scheduling resource efficiency in cases of some RO unoccupied. To achieve higher utilization efficiency, this paper studies the reusing of the PUSCH slots and occasions fixed to RACH in MsgA. By detecting the preambles in RO before the corresponding PUSCH slots, the network acquires the occupancy of the RO. Then the PUSCH occasion (PO) in reserved PUSCH can be released, which conforms to the RO detection result. The release of the previously reserved PUSCH occasions can be rescheduled and reused by the user equipment (UE) for uplink data transmission. Hence more wireless resources can be scheduled in contrast to the existing allocation of uplink share channel in 2-step type random access. It suggests that using the method improves the efficiency of resource utilization.

An Energy-Efficient DL-Aided Massive Multiple Access Scheme for IoT Scenarios in Beyond 5G Networks

In view of the challenges foreseen in futuristic massive IoT (mIoT) scenarios, characterized by a huge deployment of energy-constrained IoT devices, we propose an efficient Next Generation Multiple Access (NGMA) scheme where several innovative solutions combine and integrate. First, we aim to maximize the spectral efficiency of the Physical Uplink Shared Channel (PUSCH) by adopting the most appropriate Non-Orthogonal Multiple Access (NOMA) technique and by introducing an efficient contention-based approach for data transmission in the unused PUSCH resources. Second, on basis of the traffic load, the proposed scheme dynamically sets the UpLink (UL) radio resources dimensioning by searching the optimal trade-off between lowering the collision probability in the Physical Random Access Channel (PRACH) and providing enough radio resources in the PUSCH to permit the data transmission to all the succeeded access requests. Third, it is enriched by a series of strategic procedures to make feasible the traffic load estimation, even when the PRACH is in overload condition. Fourth, we exploit Artificial Intelligence technologies to further optimize the performances obtained. The proposed scheme is compared with other benchmark schemes available in the literature. It outperforms them in the most important metrics for the mIoT scenario (i.e., spectral efficiency and energy consumption), especially in high load conditions, which is the expected requirement for Beyond 5G and 6G networks.

Design and FPGA-Based Hardware Implementation of NB-IoT Physical Uplink Shared Channel Transmitter and Physical Downlink Shared Channel Receiver

With the anticipated growth of the internet of things (IoT) market, many low-power wide-area (LPWA) technologies have been introduced to connect a wide range of IoT devices with varying performance requirements. The narrowband internet of things (NB-IoT) is a 3rd generation partnership project (3GPP) standardized LPWA technology that meets most IoT service requirements. In this paper, the design and implementation of the physical uplink transmitting chain as well as the physical downlink receiving chain of the NB-IoT user equipment (UE) are presented. Both chains’ main blocks are designed to follow the 3GPP NB-IoT LTE standard Release 14 (Rel-14). The whole design is experimentally implemented on the Virtex 7 (VC 709) Connectivity kit, and all performance metrics are reported. Moreover, an NB-IoT base station is implemented and integrated with the two prototyped UEs to set-up an NB-IoT system, which is employed to send data from one UE to another UE through the NB-IoT base station using two FPGAs (one to implement the sending UE and the other one to implement the receiving UE) and three universal software radio peripherals (USRPs) B200 (one to implement the RF front-end of the transmitting UE FPGA, one to implement the base station RF front-end, and one to implement the RF front-end of the receiving UE FPGA). Experimental results show that the implemented NB-IoT system is working successfully, as the two NB-IoT UEs communicate together successfully through the NB-IoT base station and exchange the data properly.

CeRA-eSP: Code-Expanded Random Access to Enhance Success Probability of Massive MTC.

With the growing interest in the Internet of Things (IoT), research on massive machine-type communication (mMTC) services is being actively promoted. Because mMTC services are required to serve a large number of devices simultaneously, a lack of resources during initial access can be a significant problem when providing mMTC services in cellular networks. Various studies on efficient preamble transmission have been conducted to solve the random access problem of mMTC services. However, supporting a large number of devices simultaneously with limited resources is a challenging problem. In this study, we investigate code-expanded random access (CeRA), which extends the limited preamble resources to the code domain to decrease the high collision rate. To solve the existing CeRA phantom codeword and physical uplink shared channel (PUSCH) resource shortage problems, we propose an optimal preamble codeword set selection algorithm based on mathematical analysis. The simulation results indicate that the proposed code-expanded random access scheme to enhance success probability (CeRA-eSP) achieves a higher random access success rate with a lower access delay compared to the existing random access schemes.

Random access optimization for initial access and seamless handover for 5G-satellite network

Satellite communication is becoming an indispensable component of the 5G global networks. Considering the unique characteristics of the satellite communications such as long round trip delay, large cell radius and high satellite speed, initial access and handover are necessary to be improved to guarantee the stable communication for 5G-satellite network, which usually use the random access procedure in traditional terrestrial communication and is not suitable for satellite scenario. Therefore, a 2-step random access for 5G-satellite network (TRAS) and a seamless MC-controlled handover for 5G-satellite network (SMHOS) are proposed in this paper. In particular, the access delay can be reduced and the success rate of access can be improved since the access procedure is simplified and the contention occurs only when the UEs select the same Physical Random Access Channel (PRACH) occasion and Physical Uplink Shared Channel (PUSCH) occasion in TRAS. Moreover, in SMHOS, the management center (MC) can predict the handover of the UE and inform the next satellite to send a broadcast message with embedded information about the reserved PUSCH time–frequency resource. The UE can access to the target satellite immediately when the handover occurs, therefore, seamless handover is realized. Simulation results demonstrate the effectiveness of our TRAS and SMHOS.

Analyzing Novel Grant-Based and Grant-Free Access Schemes for Small Data Transmission

Fifth Generation (5G) New Radio (NR) does not support data transmission during random access (RA) procedures, which results in unnecessary control signalling overhead and power consumption, especially for small data transmission (SDT). Motivated by this, 3GPP has proposed 4/2-step SDT RA schemes based on the existing grant-based (4-step) and grant-free (2-step) RA schemes, with the aim to enable data transmission during RA procedures in Radio Resource Control (RRC) Inactive state. To compare the 4/2-step SDT RA schemes with the benchmark 4/2-step RA schemes, we provide a spatio-temporal analytical framework to evaluate the RA schemes, which jointly models the preamble detection, Physical Uplink Shared Channel (PUSCH) decoding, and data transmission procedures. Based on this analytical model, we derive the analytical expressions for the overall packet transmission success probability and average throughput in each RACH attempt. We also derive the average energy consumption in each RACH attempt. Our results show that 2-step SDT RA scheme provides the highest overall packet transmission success probability, and the lowest average energy consumption, but the performance gain decreases with the increase of device intensity.

An Efficient Turbo Decoding and Frequency Domain Turbo Equalization for LTE Based Narrowband Internet of Things (NB-IoT) Systems.

This paper 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 the adopted Long-Term Evolution (LTE) channel coding which presents a great challenge at the expense of high decoding complexity, power consumption, error floor phenomena, while experiencing performance degradation for short block lengths. For this reason, such a design considerably increases the overall system complexity, which is difficult to implement. Therefore, the existing LTE turbo codes are not recommended in NB-IoT systems and, hence, new channel coding algorithms need to be employed for LPWA specifications. First, LTE-based turbo decoding and frequency-domain turbo equalization algorithms are proposed, modifying the simplified maximum a posteriori probability (MAP) decoder and minimum mean square error (MMSE) Turbo equalization algorithms were 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. We compare the system performance in terms of block error rate (BLER) and computational complexity.

Correction to: An Enhanced Cooperative Communication Scheme for Physical Uplink Shared Channel in NB‑IoT

There were errors in the first and fourth authors' names in the initial online publication. The original article has been corrected.

An Enhanced Cooperative Communication Scheme for Physical Uplink Shared Channel in NB-IoT

Narrowband-IoT (NB-IoT) is a standard-based Low Power Wide Area Network technology developed to connect a wide range of new Internet of Things (IoT) devices and services. NB-IoT bandwidth is limited to a single narrow-band of 180 kHz. Although NB-IoT provides low-cost connectivity, it provides channel to large number of smart IoT installed in households, building etc. However, in NB-IoT systems, repeating same signal over additional period of time has been taken as a key technique to enhance radio coverage up to 20 dB compared to the conventional LTE. Performance of NB-IoT system optimization and modeling are still challenging particularly coverage improvement in the case of real applications. For example, the narrow bandwidth in IoT and low energy have led to problematic issues in communication between IoT devices and network station, which results in low transmitter channel quality. Repetition process is used in the paper to enhance coverage and throughput, however in mean time increase the number of repetitions demands high bandwidth. So, an enhanced cooperative relay is used with repetition to reduce the demanded bandwidth. In this paper, we proposed an enhanced repetitions cooperative process of narrowband physical uplink shared channel (NPUSCH). The NPUSCH is transmitted using one or more resource units (RUs) and each of these RUs are repeated up to 128 times to enhance coverage as well as to meet requirement of ultra-low end IoT. The optimum number of repetitions of identical slots for NPUSCH per RUs is calculated and then simulated. In addition, the paper describes the analytical simulation to evaluate the proposed repetition of cooperative process performance for LTE-NPUSCH channel. Results show dramatical enhancement of uplink NB-IoT channel quality where the performance evaluation metrics were BLER, data rate, system throughput, spectral efficiency and transmission delay. The enhanced cooperative communication scheme for NPUSCH transmission channel in NB-IoT is achieved an average 23% enhancement in overall network throughput.

Bringing AI to the edge: A formal M&S specification to deploy effective IoT architectures

ABSTRACT Internet of Things applications are based on ubiquitous networks of multiple distributed devices, with limited computing resources and power, capable of collecting and storing data from heterogeneous sources in real-time. To avoid network saturation and delays, new architectures are needed to provide real-time Big Data and data analytics capabilities at the edge of the network, where energy efficiency needs to be considered to ensure a sustainable and effective deployment in areas of human activity. In this research, we present an IoT model based on the principles of Model-Based Systems Engineering. It covers the description of the entire architecture, from IoT devices to the processing units in edge data centres, and includes the location-awareness of user equipment, network, and computing infrastructures to optimise federated resource management in terms of delay and power consumption. We present a framework to assist the dimensioning and the dynamic operation of IoT data stream analytics applications. Abbreviations : ADAS Advanced Driver Assistance System. 20, 21, 24AI Artificial Intelligence. 2, 24ANN Artificial Neural Network. 2, 21AP Access Point. 5, 10, 11, 12, 13, 17, 18, 19, 20CNF Core Network Function. 5DEVS Discrete Event System Specification. 3, 5, 6, 7, 9, 10, 11, 12, 15, 16, 17, 18, 20, 21, 24, 27, 28EDC Edge Data Centre. 2, 3, 5, 6, 9, 10, 12, 13, 20, 21, 22, 23, 25FaaS Function-as-a-Service. 3, 4, 5, 6FDD Frequency Division Duplexing. 11, 18, 19FSPL Free-Space Path Loss. 20GPU Graphics Processing Unit. 2, 21IoT Internet of Things. 2, 3, 4, 5, 6, 14, 19, 23, 24ISP Internet Service Provider. 5, 10M&S Modelling and Simulation. 3, 24M&S&O Modelling, Simulation, and Optimisation. 21MBSE Model-Based Systems Engineering. 3, 4, 5, 24MCS Modulation and Codification Scheme. 12MDC Micro Data Centre. 2ML Machine Learning. 2, 20, 24, 25NR 5G New Radio. 12P2P Point-to-Point. 5, 10PBCH Physical Broadcast Channel. 19PDCCH Physical Downlink Control Channel. 19PDSCH Physical Downlink Shared Channel. 19PSS Primary Synchronisation Signal. 11, 14PU Processing Unit. 7, 9, 21, 22, 23, 24, 25PUCCH Physical Uplink Control Channel. 19PUSCH Physical Uplink Shared Channel. 19QoS Quality of Service. 2, 4, 5, 6, 12, 24RAN Radio Access Network. 5, 10, 13, 16, 17, 20SDN Software-Defined Network. 5, 10SNR Signal-to-Noise Ratio. 11, 12, 14, 17UE User Equipment. 4, 5, 6, 10, 11, 12, 13, 14, 16, 17, 18, 19, 21, 22, 23, 24, 25WSN Wireless Sensor Network. 4

Small-Cell Assisted Group Paging for Massive MTC in LTE Networks: Design and Analysis

Long-Term Evolution cellular networks are the main enabler for the massive Machine-Type Communications service and therefore must handle a large number of Machine-Type Devices (MTDs). To control the number of devices allowed to contend on the Physical Random Access Channel (PRACH), the group paging scheme that divides the MTDs into smaller groups and lets the network sequentially trigger the groups has been studied. However, as the number of PRACH preambles is limited, a group’s size must be kept relatively small compared to the MTD population. This paper exploits the possibility that a significant portion of the MTDs is also covered by densely deployed small-cells such that a Small-cell Base Station (SBS) may act as a representative for its MTDs during the preamble transmission step to reduce the load on PRACH. Once the SBS succeeds, its MTDs then contend locally to send their own signaling messages on the corresponding reserved uplink resources. Computer simulations show that the manageable group size can be significantly increased at a reasonable cost on the Physical Uplink Shared Channel. A theoretical model to quickly predict the effect of the ratio of MTDs that are under the coverage of the SBSs is also derived and verified.

A New Contention-Based PUSCH Resource Allocation in 5G NR for mMTC Scenarios

This letter addresses the uplink radio resource allocation problem in a 5G massive Machine Type Communication (mMTC) scenario, where a large number of MTC devices generate small-sized packets. The current cellular networks are unsuitable for this scenario, due to the limited resources allocated to the Physical Random Access Channel (PRACH) and to the Physical Uplink Shared Channel (PUSCH). To overcome this issue, instead of improving the succeeded access attempts in the PRACH, as widely addressed in literature, we focus on the PUSCH. We present the innovative idea to exploit the unused PUSCH resources to serve also the MTC devices that have failed their access attempt, by assigning them a pool of resources, in a contention-based mode. The simulation results show that the proposed PUSCH Resource Reallocation Algorithm improves significantly any static and dynamic system performance in terms of number of succeeded communications, at the cost a negligible increment of energy consumption.

Enhanced Random Access for Massive-Machine-Type Communications

In this article, we study a random access (RA) scheme to alleviate the RA channel (RACH) overload problem in the massive-machine-type communication (mMTC) environment. We first propose a timing advance-based preamble resource expansion (TAPRE) scheme which effectively increases preamble resources and reduces the preamble collision probability by adjusting preamble transmission timing with timing advance (TA) information. We also propose a resource allocation wait (RAW) scheme which efficiently reduces the number of RA failures due to the lack of physical uplink shared channel (PUSCH) resources. We then propose an overall procedure for enhanced RA with TAPRE and RAW (ERATAR). In addition, we provide the analysis of RA performance by applying more practical assumptions than the existing analysis. We validate our analysis with the system level simulation based on NS-3, and compare the various performances of our ERATAR to those of existing works. Numerical results show that our analysis provides more accurate results than the existing work and our ERATAR provides significantly improved performances compared with those of existing works.

Joint Control of Random Access and Dynamic Uplink Resource Dimensioning for Massive MTC in 5G NR Based on SCMA

The massive machine-type communication (mMTC) usage scenario, also known as the massive Internet of Things (mIoT), involves a huge number of MTC devices having high requirements on increased battery lifetime, which autonomously transfer small amounts of data with relaxed delay requirements, without human intervention. The current cellular network is unsuitable for this scenario, due to the limited uplink resources allocated to the physical random access channel (PRACH) and to the physical uplink shared channel (PUSCH). With this in mind, in this article, we propose a new framework, customized for massive MTC services, that includes a joint control of the dynamic resource allocation between the PRACH and the PUSCH, and a new random access (RA) procedure based on an adaptive access class barring (ACB) scheme that appropriately spreads RA reattempts in time. In addition, to further increase the transmission efficiency, we adopt the sparse code multiple access (SCMA) technique for PUSCH resources, because SCMA results as the most promising nonorthogonal multiple access (NOMA) technique to support massive MTC connectivity with small-size data. The simulation results show that the proposed control framework significantly improves the number of succeeded communications in comparison with the other proposals available in the literature. Furthermore, an energy consumption model is introduced to show the considerable energy saving achieved by the MTC devices which adopt our joint control scheme.

Non-Orthogonal Random Access and Data Transmission Scheme for Machine-to-Machine Communications in Cellular Networks

In order to address the signalling overhead and resource allocation problems of Machine-to-Machine (M2M) communications with non-orthogonal multiple access (NOMA), we propose a hybrid non-orthogonal random access and data transmission (NORA-DT) scheme. A novel design of NORA-DT protocol for M2M communications in cellular networks is firstly proposed. A power back-off scheme is introduced to adjust machine-type communications device (MTCD)'s target arrived power, and a closed-form analytic formula for the relation of MTCD's transmission power is derived. Based on the transmission power relation, the devices are clustered into a set of NOMA clusters. In the hybrid NORA-DT protocol, the cluster center MTCD transmits a extended preamble on behalf of the MTCDs in the same NOMA cluster on the physical random access channel (PRACH) for connection request. Base station (BS) can perfectly detect the preamble collisions in advance and schedules physical uplink shared channel (PUSCH) only to the NOMA clusters without collision. Then the MTCDs in the same NOMA clusters transmit data packets right after preamble transmission on the PUSCH to reduce the signalling overhead. By finding the optimal power allocation, we propose a low-complexity energy efficiency maximization problem for NORA-DT scheme. Due to the relation of MTCD's transmission power, we transform the problem into the function of cluster center MTCD's transmission power and solve it by difference of convex (DC) programming under the maximum transmission power constraints and minimum rate requirements at the MTCDs. A computationally efficient adaptive resource allocation scheme is finally proposed to improve the system throughput and resource usage. The optimal resource allocation between PRACH and PUSCH for any number of MTCDs can be learned by BS in advance, which avoids frequent computation. The analytic model is validated by simulation results. We demonstrate that the proposed NORA-DT scheme can significantly improve the system throughput, resource efficiency and energy efficiency performance.

An Efficient Polar Coding Scheme for Uplink Data Transmission in Narrowband Internet of Things Systems

Narrowband Internet of Things (NB-IoT) is an emerging IoT cellular-based wireless technology that builds based on the existing LTE standard to extend its network coverage suited for Low Power Wide Area Network (LPWAN) connectivity. In the NB-IoT system, LTE turbo codes and Cyclic Redundancy Check (CRC) codes are adopted as the main channel coding technique for Narrowband Physical Uplink Shared Channel (NPUSCH). However, turbo codes require iterative decoding algorithm at the expense of high computation complexity of decoding hence is crucial to achieving the LPWAN requirement of NB-IoT systems. Polar codes are best suited in this regard due to its capacity approaching and complexity reduction in short block length code. In this paper, 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.

Analysis of 5G New Radio Uplink Signals on an Analogue-RoF System Based on DSP-Assisted Channel Aggregation

The 3rd Generation Partnership Project (3GPP) is in the process of developing 5th generation (5G) radio access technology, the so-called new radio (NR). The aim is to achieve the performance requirements forIMT-2020 radio interface technology. In this paper, we focus on the analysis of the transmission of 5G NR uplink physical channels, such as physical uplink shared channel (PUSCH) and physical uplink control channel (PUCCH), dedicated for data and control channels, respectively, as specified in the 3GPP standard, using digital signal processing (DSP)-assisted frequency division multiple access (FDMA) and time division multiple access (TDMA) channel aggregation techniques on an analogue radio-over-fiber (A-RoF) architecture. We verified that there is ~34% spectral efficiency gain and lower error vector magnitude (EVM) achieved using the TDMA technique.

Dynamic Access Control With Resource Limitation for Group Paging-Based Cellular IoT Systems

In cellular Internet-of-Things (IoT) systems, system overload may occur during a random access (RA) procedure under a limited number of preamble resources and physical uplink shared channel (PUSCH) resources especially when there exist massive IoT devices in a cell. In order to resolve the system overload, the commercial system like 3GPP LTE adopted a group paging (GP)-based uplink access technique, but it has been known that the performance of the GP-based technique drastically degrades as the number of devices increases. In this paper, we first propose a dynamic access control (DAC) mechanism for the GP-based cellular massive IoT system, which dynamically adjusts RA-attempting probability by considering not only the number of available preambles but also the number of available PUSCH resources. We also intelligently combine the proposed DAC mechanism with an early preamble collision detection technique to further improve the RA performance of the cellular IoT system. Through extensive computer simulations, we show that the proposed DAC mechanism outperforms the conventional access control mechanisms, which consider only the number of available preamble resources, in terms of GP completion time, PUSCH resource efficiency, transmission efficiency, and energy efficiency.