Modulation And Coding Scheme Level Research Articles

Deep Learning-Driven Interference Perceptual Multi-Modulation for Full-Duplex Systems

In this paper, a novel data transmission scheme, interference perceptual multi-modulation (IP-MM), is proposed for full-duplex (FD) systems. In order to unlink the conventional uplink (UL) data transmission using a single modulation and coding scheme (MCS) over the entire assigned UL bandwidth, IP-MM enables the transmission of UL data channels based on multiple MCS levels, where a different MCS level is applied to each subband of UL transmission. In IP-MM, a deep convolutional neural network is used for MCS-level prediction for each UL subband by estimating the potential residual self-interference (SI) according to the downlink (DL) resource allocation pattern. In addition, a subband-based UL transmission procedure is introduced from a specification point of view to enable IP-MM-based UL transmission. The benefits of IP-MM are verified using simulations, and it is observed that IP-MM achieves approximately 20% throughput gain compared to the conventional UL transmission scheme.

Two-Stage Thompson Sampling for Outer-Loop Link Adaptation

In this letter, we consider outer-loop link adaptation, wherein we pursue to find the optimum modulation and coding scheme (MCS) that provides the maximum throughput without directly estimating the channel state. We cast this problem in a form of multi-armed bandit, an online decision making policy based on sequential observations. To efficiently solve a formulated problem, we propose a novel two-stage Thompson sampling. The proposed method is built based on the observation that the optimum MCS level appears in a certain group that satisfies feasibility conditions. Exploiting this feature, we find the optimum MCS level via two stages. In the first stage, we identify a group that has high probability of including the optimum MCS. In the second stage, we only focus on the MCS levels within the identified group in the first stage, and investigate the optimum MCS. By doing this, the search space is significantly reduced, which leads to the performance improvement. Simulation results show that the proposed method outperforms the existing state-of-art algorithm.

Dynamic Bandwidth Part Allocation in 5G Ultra Reliable Low Latency Communication for Unmanned Aerial Vehicles with High Data Rate Traffic.

The 3GPP standardized the physical layer specification in 5G New Radio to support enhanced mobile broadband (eMBB) and ultra-reliable low-latency communication (URLLC) coexistence in usage scenarios including aerial vehicles (AVs). Dynamic multiplexing of URLLC traffic was standardized to increase the outage capacity. DM allocates a fully overlapped bandwidth part (BWP) of eMBB and URLLC AVs to perform the immediate scheduling of URLLC traffic by puncturing ongoing eMBB traffic. However, DM often suffers from a significant frame error incurred by puncturing. Meanwhile, BWP can be sliced orthogonally for eMBB and URLLC AVs, possibly preventing overdimensioning the resources depending on the eMBB and URLLC traffic loads. In this paper, we propose a dynamic BWP allocation scheme that switches between two multiplexing methods, dynamic multiplexing (DM) and orthogonal slicing (OS), so as to minimize an impact of uRLLC traffic on eMBB traffic. To implement efficient BWP allocation, the capacity region is analyzed by considering the effect of physical layer parameters, such as modulation and coding scheme (MCS) levels and code block group size on DM and OS. OS is effective for improving the eMBB throughput under a URLLC latency constraint for deterministic and predictable URLLC traffic, whereas DM has limited error-correcting capability against the URLLC’s puncturing effect. The relative MCS level of eMBB and URLLC is critical in determining the eMBB traffic tolerance against puncturing. Identifying the performance tradeoff between DM and OS, the tolerance level is quantified by a URLLC load threshold. It is given in an approximate closed form, which is an essential reference for selecting DM over OS, enabling dynamic BWP allocation for the URLLC AV.

SINR-Based MCS Level Adaptation in CSMA/CA Wireless Networks to Embrace IoT Devices

This paper presents an automatic modulation and coding scheme (MCS) level adaptation algorithm to embrace Internet of Things (IoT) devices by improving the area spectral efficiency of carrier-sense multiple access with collision avoidance (CSMA/CA) wireless networks. In the proposed algorithm, senders of CSMA/CA wireless networks use the signal to interference plus noise ratio of acknowledgment frames from their receivers to estimate channel statuses between the senders and the receivers. Using the estimated channel status of each receiver, senders control sending rates of traffic by adjusting MCS levels of packets destined for each receiver. We use Poisson point processes (PPPs) to model the locations of participating nodes (i.e., access points and wireless devices) in a given area. We evaluate the effectiveness of the proposed algorithm using an event-driven ns-2 simulator for various PPP densities of access points and wireless devices.

Scalable Video Coding-based MIMO Broadcasting System With Optimal Power Control

This paper presents a scalable video coding (SVC)-based open-loop multi-input multioutput (MIMO) scheme for broadcast services such as LTE broadcast/evolved multimedia broadcast multicast service and terrestrial broadcast TV/ATSC 3.0. It intends to guarantee the minimum essential information (as a base layer) and obtain additional information for improving the video quality (as enhancement layers) when multiple transmit and receive antennas are employed. Two types of SVC-based open-loop MIMO broadcasting schemes are considered: 1) SVC-MIMO-time division multiplexing (TDM) and 2) SVC-MIMO-spatial multiplexing (SM). They provide differentiated video quality that depends on the average channel gain of individual users by employing different modulation and coding scheme (MCS) levels for unequal error protection of individual layers, i.e., a lower MCS level for the base layer and a higher MCS level for the enhancement layers. In particular, SVC-MIMO-SM extends the per-layer service coverage by performing a block-wise successive interference cancellation (SIC) from the base layer up to the highest enhancement layer in the receiver. As a result, the base layer can be decoded with the most robust MCS while the enhancement layers can be decoded with an SIC diversity gain. Furthermore, we formulate an optimal power allocation problem for the SVC-MIMO-SM scheme that can maximize the average system utility function while ensuring the target service coverage. Optimal solutions for different cases are derived by identifying the Karush–Kuhn–Tucker conditions for the given problem. Our numerical results demonstrate that the optimal power allocation provides more average system utility gain than SVC-MIMO-TDM and SVC-MIMO-SM without power control schemes, indicating the enhancement in the per-layer service coverage performance.

Performance analysis of centralised and distributed scheduling schemes for mobile multihop relay systems

For a mobile multihop relay (MMR) system, a centralised packet scheduling method is compared with a distributed packet scheduling method. The performance of the MMR system considering the joint effect of a finite-length queue and an adaptive modulation and coding scheme for base station and relay station is analysed. A finite state Markov chain (FSMC) describing the queue and channel state pairs’ transitions for the MMR system is built. Moreover, a method of reducing the state space of the FSMC, which enables a hop-by-hop performance analysis of the MMR system without explosive growth in the number of states, is presented. Numerical and simulation results show that the proposed FSMC modelling is accurate and the performance of centralised scheduling becomes degraded because of increased mismatches between a scheduled modulation and coding scheme (MCS) level and the actual MCS level.

Uplink Scheduling and Link Adaptation for Narrowband Internet of Things Systems

Narrowband Internet of Things (NB-IoT) is a new narrow-band radio technology introduced in the Third Generation Partnership Project release 13 to the 5th generation evolution for providing low-power wide-area IoT. In NB-IoT systems, repeating transmission data or control signals has been considered as a promising approach for enhancing coverage. Considering the new feature of repetition, link adaptation for NB-IoT systems needs to be performed in 2-D, i.e., the modulation and coding scheme (MCS) and the repetition number. Therefore, existing link adaptation schemes without consideration of the repetition number are no longer applicable. In this paper, a novel uplink link adaptation scheme with the repetition number determination is proposed, which is composed of the inner loop link adaptation and the outer loop link adaptation, to guarantee transmission reliability and improve throughput of NB-IoT systems. In particular, the inner loop link adaptation is designed to cope with block error ratio variation by periodically adjusting the repetition number. The outer loop link adaptation coordinates the MCS level selection and the repetition number determination. Besides, key technologies of uplink scheduling, such as power control and transmission gap, are analyzed, and a simple single-tone scheduling scheme is proposed. Link-level simulations are performed to validate the performance of the proposed uplink link adaptation scheme. The results show that our proposed uplink link adaptation scheme for NB-IoT systems outperforms the repetition-dominated method and the straightforward method, particularly for good channel conditions and larger packet sizes. Specifically, it can save more than 14% of the active time and resource consumption compared with the repetition-dominated method and save more than 46% of the active time and resource consumption compared with the straightforward method.

Interference Cancellation and Adaptive Demodulation Mapping Schemes for Device-to-Device Multicast Uplink Underlaying Cellular Networks

Device-to-device multicast (D2MD) communications enable dissemination of messages directly from one user equipment (UE) to a group of D2D UEs (DUEs) located in close proximity, instead of routing via the base station. The challenges of D2MD arise from the interference to and from in-band cellular UEs (CUEs) due to frequency reuse, and the low data transmission rate constrained by the worst channel quality. To improve the overall system capacity, a novel interference coordination scheme and an adaptive demodulation mapping scheme (ADMS) based on rateless encoding technique is proposed. Firstly, a new interference limited area control scheme that reduces the interference from CUEs to each DUE is proposed. In the proposed scheme, the DUEs share same resource with the CUEs out of the interference limited area. Secondly, the ADMS working principle is described. In ADMS, the bits are modulated by a high level modulation and coding scheme (MCS), and each DUE can adaptively select one MCS level to demodulate bits according to the channel state information. Finally, the expressions of two performance metrics are derived, namely D2MD system delay and energy consumption, and a distance minimization problem (DMP) with attenuation function to achieve the tradeoff between the two metrics is formulated. From the simulation results, it is confirmed that the proposed schemes improve the performance of the hybrid system compared to the conventional ways. In addition, by controlling the introduced parameter, DMP can balance the tradeoff between the two metrics effectively.

Application-Aware MCS Level Selection Method for Cross-Layered Retransmission Scheme

In this letter, we propose an application-aware modulation and coding scheme (MCS) level selection method for a cross-layered retransmission scheme. The existing MCS level selection methods use fixed target packet error rate (PER) only and do not take into account quality of service (QoS) requirements for an application. This may cause a discrepancy between the QoS requirements of an application and the criterion for selection of an MCS level. Therefore, the channel utilization is decreased due to the discrepancy. To remove the discrepancy, the application-aware MCS level selection method adjusts a target PER according to the type of application. We have shown that the proposed scheme can improve the wireless channel utilization.

Two-Step Resource Block Allocation Algorithm for Data Rate Maximization in LTE Downlink Systems

This study focuses on resource block allocation issue in the downlink transmission systems of the Long Term Evolution (LTE). In existing LTE standards, all Allocation Units (AUs) allocated to any user must adopt the same Modulation and Coding Scheme (MCS), which is determined by the AU with the worst channel condition. Despite its simplicity, this strategy incurs significant performance degradation since the achievable system throughput is limited by the AUs having the worst channel quality. To address this issue, a two-step resource block allocation algorithm is proposed in this paper. The algorithm first allocates AUs to each user according to the users' priorities and the number of their required AUs. Then, a re-allocation mechanism is introduced. Specifically, for any given user, the AUs with the worst channel condition are removed. In this manner, the users may adopt a higher MCS level, and the achievable data rate can be increased. Finally, all the unallocated AUs are assigned among users without changing the chosen MCSs, and the total throughput of the system is further enhanced. Simulation results show that thanks to the proposed algorithm, the system gains higher throughput without adding too many complexities.

An MIMO Configuration Mode and MCS Level Selection Scheme by Fuzzy Q-Learning for HSPA⁺ Systems

In this paper, we propose a fuzzy Q-learning-based MIMO configuration mode and MCS level (FQL-MOMS) selection scheme for high speed packet access evolution (HSPA+) systems. The FQL-MOMS selection scheme intends to enhance the system throughput under the block error rate (BLER) requirement guarantee. It will determine an appropriate MIMO configuration mode and MCS (modulation and coding scheme) level for packet data transmission in HSPA+ systems, under the situations that the channel status is varying and the channel quality indication (CQI) has report delay. The FQL-MOMS scheme considers not only the reported CQI and the last transmission result but also the BLER performance metric and the transmission efficiency. Moreover, it is effectively configured, where the fuzzy rules and the reinforcement signals for the Q-learning algorithm are sophisticatedly designed. Simulation results show that the proposed FQL-MOMS scheme increases the system throughput by up to 49.3 and 35.9 percent, compared to the conventional adaptive threshold selection (ATS) scheme [12] and the Q-HARQ scheme [14], respectively, under the BLER requirement fulfillment.

무선 LAN 시스템에서의 SNR 오프셋을 이용한 링크 적응화

링크 적응 기법은 변하는 채널 조건에 맞는 최적의 MCS 레벨을 선택한다. 무선 LAN 시스템을 위한 다양한 링크 적응 알고리즘이 제안되었으나 802.11n과 같은 최근의 시스템에서 최적의 성능을 보장하지는 않는다. 본 논문에서는 수신 SNR과 전송 결과에 따라 얻어지는 오프셋 값을 이용한 새로운 링크 적응 알고리즘을 제안한다. 802.11n 시스템에서 모의실험을 하여 제안된 알고리즘과 잘 알려져 있는 ARF 및 일반적인 SNR기반 알고리즘과 그 성능을 비교해본다. 제안된 알고리즘은 PER에 제한이 있는 경우 시변채널에서 더 좋은 성능을 보인다. Link Adaptation should select the best modulation and coding scheme (MCS) which gives the highest throughput as channel conditions vary. Several link adaptation algorithms for wireless local area network (WLAN) have been proposed but for the future WLAN systems such as 802.11n system, these algorithms do not guarantee the best performance. In this paper, we propose a new link adaptation algorithm in which an MCS level is chosen by the received SNR plus the offset value obtained from the transmission results. The performance of proposed algorithm is simulated by an IEEE 802.11n system. From the analysis, we conclude the proposed algorithm performs better than the well-known link adaptation algorithms such as auto rate fallback and general SNR-based techniques. Particularly, the proposed algorithm improves throughput when the packet error ratio (PER) is constrained for fast fading channels.

Simultaneous transmission of MAP IE and data for minimizing MAC overhead in the IEEE 802.16e OFDMA systems

An advanced MAP transmission scheme for improving media access control (MAC) overhead in the IEEE 802.16e systems is proposed. In the IEEE 802.16e system, when a base station (BS) broadcasts a MAP message, which is a control message about scheduling information, it applies a robust modulation and coding scheme (MCS) level and allocates a large amount of radio resources, which induce a huge MAP overhead. Our proposed scheme utilizes piggybacked MAP IEs, in which control messages are concatenated with data packets and transmitted with the MCS level applied to data transmission. Due to the fact that the rate at which data is transmitted is generally higher than the rate at which broadcasting messages are transmitted, the proposed scheme can increase average data rate of a MAP transmission and consequently reduce the amount of resources allocated to the MAP transmission. Numerical analysis and simulations are presented to show that the MAP overhead is critical to system performance and can be improved by the proposed scheme.

Optimal modulation and coding scheme selection in cellular networks with hybrid-ARQ error control

We propose an optimal modulation and coding scheme (MCS) selection criterion for maximizing user throughput in cellular networks. The proposed criterion adopts both the Chase combining and incremental redundancy based hybrid automatic repeat request (HARQ) mechanisms and it selects an MCS level that maximizes the expected throughput which is estimated by considering both the number of transmissions and successful decoding probability in HARQ operation. We also prove that the conventional MCS selection rule is not optimized with mathematical analysis. Through link-level and system-level simulations, we show that the proposed MCS selection criterion yields higher average cell throughput than the conventional MCS selection schemes for slowly varying channels.

Adaptive Modulation and Coding Scheme with Independent MCS Level Selection in MIMO Systems

In this paper, we propose a system that adopts the independent MCS (modulation and coding scheme) level for each layer in the AMC (adaptive modulation and coding) scheme combined with the V-BLAST (vertical Bell lab layered space time) system. From the simulation results, we observe that since the independent MCS level case adapts modulation and coding rate for maximum throughput to each channel condition in separate layers, the combined AMC-V-BLAST system with the independent MCS level selection results in improved throughput compared to the combined AMC-V-BLAST system with the common MCS level selection and the conventional AMC system based on the 1x EV-DO standard. Especially, the combined AMC-V-BLAST system with the independent MCS level achieves a gain of 700 kbps in 7–9 dB SNR (signal-to-noise ratio) range.

Adaptive Bit-Interleaved Coded OFDM With Reduced Feedback Information

If the channel is static and is perfectly known to both the transmitter and the receiver, the water-filling technique with adaptive modulation is known to be optimal (Gallager, 1968). However, for orthogonal frequency-division multiplexing (OFDM) systems, this requires intensive traffic overheads for reporting channel state information on all subcarriers to the transmitter. In this paper, we consider an adaptive modulation and coding scheme for bit-interleaved coded OFDM with reduced feedback information satisfying a specified quality of service level. We propose a rate adaptation scheme, which utilizes the estimated bit error rate for supportable transmission rates. In this scheme, a user equipment chooses a modulation and coding scheme (MCS) level, which can provide the maximum spectral efficiency based on one OFDM symbol rather than on all subchannels. Then the user needs to send back only the selected MCS level index. The proposed scheme does not require the water-filling procedure, and the amount of the feedback information reduces to a single integer value irrespective of the number of subcarriers. Simulation results show that the proposed scheme can significantly reduce the system complexity while minimizing the performance loss compared to the optimum water-filling scheme.

Evaluation of Asymmetric TDD Systems Employing AMC and HARQ by Considering MCS Selection Errors

In this paper, we evaluate the performance of asymmetric Time Division Duplex (TDD) system that employs Adaptive Modulation and Coding (AMC) and Hybrid ARQ, with consideration of the effect of control delays in TDD. Channel reciprocity characteristic in TDD allows utilization of open loop channel estimation to choose appropriate modulation and coding scheme (MCS) level for AMC. However, control delay in AMC and HARQ depends on TDD time slot allocation formats. Large control delay in AMC will result in false MCS selection due to the poor channel correlation between measured channel state from the received signals and instantaneous channel state of actual transmission with the MCS selected based on the measured channel state. We present an analytical approach to calculate the probability of MCS level selection error in different channel conditions for different asymmetric time slot allocations. From the theoretical and simulation results, it is shown that the instantaneous throughput per slot depends not only on maximum Doppler frequency but also on asymmetric slot allocations. Average delay time that yields error free packet reception in the downlink increases as the number of continuous downlink slots increases.

A Velocity Estimation-Based Channel Estimator for WCDMA Forward Link Receiver

In this letter, we propose a new practical architecture of channel estimator that can compensate for the signal distortion due to variable mobile station velocity in WCDMA forward link. The proposed Channel Estimator consists of IIR filter for channel estimation and Velocity Estimator for selection of IIR filter coefficients matched to mobile station velocity. The combination of IIR filter and Velocity Estimator can overcome the divergence problem of IIR filter due to the mobile station velocity. The Velocity Estimator estimates the speed of mobile station velocity by observing power spectrum of the received signal and exhibits stable operation in low SNR environment. To improve the resolution of velocity estimation without additional complexity due to large FFT size, an interpolator is adopted in the velocity estimator. The proposed channel estimation architecture can not only be used for WCDMA forward link but also is applicable for CDMA-2000 system without major modifications. Also, the Velocity Estimator can be applied in the channel quality measurement for the selection of MCS (Modulation and Coding Scheme) level in HSDPA transmission.