Towards Integrated Sensing and Communications for 6G: A Standardization Perspective

The radio communication division of the International Telecommunication Union (ITU-R) has recently adopted Integrated Sensing and Communication (ISAC) among the key usage scenarios for IMT-2030/6G. ISAC is envisioned to play a vital role in the upcoming wireless generation standards. In this work, we bring together several paramount and innovative aspects of ISAC technology from a global 6G standardization perspective, including both industrial and academic progress. Specifically, this article provides 6G requirements and ISAC-enabled vision, including various aspects of 6G standardization, benefits of ISAC co-existence, and integration challenges. Moreover, we present key enabling technologies, including intelligent metasurface-aided ISAC, as well as Orthogonal Time Frequency Space (OTFS) waveform design and interference management for ISAC. Finally, future aspects are discussed to open various research opportunities and challenges on the ISAC technology towards 6G wireless communications.Comment: 7 pages, 5 figure

Hybrid Active User Detection for Massive Machine-type Communications in IoT

Massive machine-type communication (mMTC) concerns the access of massive machine-type communication (MTC) devices to the basestation. To support the massive connectivity, non-orthogonal multiple access (NOMA) and grant-free access have been recently introduced. In grant-free access, each device transmits information without scheduling so that the basestation needs to identify the active devices among all potential devices in a cell. This process, called an active user detection (AUD), is a challenging problem for the NOMA-based systems since it is difficult to find out the active devices from the superimposed received signal. To address this problem, compressed sensing (CS) based active user detection (All)) technique exploiting the low activity of devices in mMTC has been introduced. In this paper, we propose an All) scheme that exploits both pilot and data measurements to improve the All) performance in grant-free NOMA systems. The key idea is to use the common support information of pilot and data signals in a packet. Numerical results demonstrate that the proposed ALT) scheme outperforms the conventional approaches in both AUD and throughput performance.N

Channel Aware Sparse Signaling for Ultra Low-latency Communication in TDD systems

Fifth generation (5G) wireless networks are currently being developed to handle wide variety of use cases. In order to support these cases, new types of requirements other than throughput enhancement have been introduced. One such requirement is to reduce the latency down to a millisecond (ms) level in ultra reliable and low latency communications (URLL-C). In case of uplink transmission, supporting this stringent latency requirement is quite challenging and problematic since the scheduling procedure is a time-consuming and complicated handshaking process. In time division duplexing (TDD) systems, satisfying the latency requirement is far more difficult since the mobile device cannot transmit the data when the subframe is assigned for the downlink. In this paper, we propose a new type of uplink transmission scheme for TDD-based URLLC. Key idea of the proposed scheme is to transmit the latency sensitive data immediately after performing the ultra-short one-way signaling from the basestation to the mobile device. To reduce the processing time of grant signal, we present a fast signaling mechanism, referred to as channel-aware sparse signaling (CASS). Numerical results confirm that the proposed uplink transmission scheme is very effective in TDD-based URLLC systems.N

New Radio Technologies for Ultra Reliable and Low Latency Communications

Ultra reliable and low latency communications (URLLC) is a new use case in SG wireless systems to accommodate emerging mission-critical services and applications. These include driverless vehicles and drone-based deliveries, smart cities and factories, remote medical diagnosis and surgery, and artificial intelligence-based personalized assistants. In order to support URLLC, there should be changes in the air interface (a.k.a. physical-layer). In this article, we provide physical layer challenges and solutions in SG URLLC downlink We discuss requirements of URLLC and then present the physical layer issues and new solutions including data structure, multiplexing schemes, and reliability assurance technologies, which have been adopted in the SG new radio (NR).N

Fast Uplink Access in TDD Systems for Ultra Reliable and Low Latency Communications

Fifth generation (5G) wireless networks are currently being developed to handle wide variety of use cases. In order to support these cases, new types of requirements other than throughput enhancement have been introduced. One such requirement is to reduce the latency down to a millisecond (ms) level in ultra reliable and low latency communications (URLLC). In case of uplink transmission, supporting this stringent latency requirement is quite challenging since the scheduling procedure is a time-consuming and complicated handshaking process. In time division duplexing (TDD) systems, satisfying the latency requirement is far more difficult since the mobile device cannot transmit the data when the subframe is assigned for the downlink. In this paper, we propose a low latency access scheme suitable for TDD-based URLLC. Key idea of the proposed scheme is to transmit the latency sensitive data immediately after the grant signaling. To support the fast uplink access, we introduce a fast grant signaling scheme based on the compressed sensing technique. Numerical results confirm that the proposed uplink access scheme is very effective in TDD-based URLLC systems.N

Channel Aware Sparse Signaling for Ultra-low Latency TDD Access

Future mobile communication systems need to support wide variety of new services and applications. In order to support these, ITU-R introduced new types of use cases. One such use case, called ultra reliable and low latency communication (URLLC), concerns the reduction of latency down to a millisecond level while ensuring the reliability of the transmission. In case of uplink transmission, supporting the stringent latency requirement of URLLC is quite challenging due to a time-consuming and complicated handshaking process. In the time division duplexing (TDD) systems, satisfying the latency requirement is far more difficult since the mobile device cannot transmit the data when the subframe is directed to the downlink. In this paper, we propose a new grant signaling scheme, referred to as channel-aware sparse signaling (CASS), to achieve a low latency access in the TDD-based URLLC systems. Key idea of CASS is to map the grant information into a small number of subcarriers and then decode it using a small number of early received samples. From the numerical evaluations, we demonstrate that the proposed CASS scheme achieves significant reduction in access latency over the conventional LTE-TDD systems.N