Hybrid Transmission Scheme Research Articles

Energy efficient multi-user task offloading through active RIS with hybrid TDMA-NOMA transmission

In this paper, we address the challenge of minimizing system energy consumption for task offloading within non-line-of-sight (NLoS) mobile edge computing (MEC) environments. Our approach integrates an active reconfigurable intelligent surface (RIS) and employs a hybrid transmission scheme combining time division multiple access (TDMA) and non-orthogonal multiple access (NOMA) to enhance the quality of service (QoS) for user task offloading. The formulation of this problem as a non-convex optimization issue presents significant challenges due to its inherent complexity. To overcome this, we introduce an innovative method termed element refinement-based differential evolution (ERBDE). Initially, through rigorous theoretical analysis, we optimally determine the allocation of local computation resources, computation resources at the base station (BS), and transmit power of users, while maintaining fixed values for the offloading ratio, amplification factor, phase of the reflecting element, and the transmission period. Subsequently, we employ the differential evolution (DE) algorithm to iteratively fine-tune the offloading ratio, amplification factor, phase of the reflecting element, and transmission period towards near-optimal configurations. Our simulation results demonstrate that the implementation of active RIS-supported task offloading utilizing the hybrid TDMA-NOMA scheme results in an average system energy consumption reduction of 80.3%.

Analysis and design of multi-mode power split hybrid transmission scheme considering mode connection

For heavy-duty truck, multi-mode power split hybrid transmission scheme (MPSHTS) has good adaptability. However, the moment of inertia at both ends of the clutch is large. If there is a large speed difference in the clutch engagement process, it will increase clutch wear, engine stall and other problems. This paper proposed a new design method of multi-mode power split hybrid powertrain, which was different from the proof by exhaustion aiming at mode switching without speed difference. It included: the conditions for achieving mode connection without speed difference was obtained based on the lever method for dynamic characteristic analysis. Evaluation index for power split mechanisms that comprehensively considered power source and transmission system was established. Combining the mode connection conditions and the optimized basic configuration, the characteristic of no speed difference could be ensured by adjusting the power coupling mechanism. A multi-mode scheme based on optimized configuration and work mode requirements could be obtained. Finally, parameter matching and simulation verification on the designed scheme was carried out. It suggested that the designed system improved fuel economy by 4.14% compared with the original scheme.

Hybrid transmission scheme using FBMC and OFDM under multipath fading channels

Hybrid transmission scheme using FBMC and OFDM under multipath fading channels

Hybrid Transmission Scheme for Improving Link Reliability in mmWave URLLC Communications

Ultra-Reliable and Low-Latency Communication (URLLC) represents a key ingredient of current 5G and future 6G mobile communication networks. The demanding reliability requirement set for URLLC claims for novel techniques that can deliver the necessary level of reliability without sacrificing the overall system capacity. In this context, this work presents and analyses a hybrid transmission scheme for improved reliability in millimetre wave bands with adaptive diversity combining. The proposed scheme is based on a hybrid approach that combines two links, one in the FR1 band (characterised by lower capacity but higher reliability due to more favourable propagation) and one in the FR2 band (offering higher capacity but experiencing a less reliable connectivity). The proposed scheme dynamically adapts the usage of both links in order to exploit the complementary characteristics of both bands (reliability of FR1 bands and capacity of FR2 bands) by switching between FR2-only and joint FR1-FR2 transmission according to the instantaneous channel quality in the main FR2 link. The performance is evaluated under two popular and well-known diversity combining techniques, namely Selection Combining (SC) and Maximal Ratio Combining (MRC). The obtained results demonstrate that the proposed scheme can achieve the same level of reliability as a continuous dual-link transmission scheme but with a much lower level of links usage and without sacrificing (and indeed enhancing) the capacity, thus making it a suitable candidate to deliver URLLC services in a resource-efficient manner.

Improving the Tracking Accuracy of TDMA-Based Acoustic Indoor Positioning Systems Using a Novel Error Correction Method

To improve the tracking accuracy of moving target by the acoustic indoor positioning system (AIPS) using time division multiplexing access (TDMA) technology, a novel TDMA correction method is proposed. The main idea of the proposed method is to convert the movement of the target into the movement of the audio base station. Specifically, the base station is moved according to the estimated velocity so that the distance between the base station after being moved and the current target position is equal to the length of the path through which the audio emitted by the base station reaches the target, and then the coordinates of the base station after being moved are used for positioning, so as to realize the error correction. Both simulations and acoustic indoor moving target tracking experiments were conducted to evaluate the performance of the proposed method. The simulation results show that the tracking errors of TDMA-based AIPS on moving targets can be effectively corrected under the condition that the velocity and measurement noise meet the corresponding thresholds. In the moving target positioning experiments, compared with the positioning accuracy before correction, the positioning accuracy after correction is improved by about 0.20 m (90%) in TDMA-only transmission scheme and about 0.08 m (90%) in hybrid transmission scheme of TDMA and FDMA. The proposed method has an important application value in improving the tracking accuracy of TDMA-based AIPS for moving targets.

A Collaborative Caching-Transmission Method for Heterogeneous Video Services in Cache-Enabled Terahertz Heterogeneous Networks

To mitigate the impact of the dramatic growth of wireless video traffic and provide users with heterogeneous video services, a collaborative caching-transmission method in cache-enabled terahertz (THz) heterogeneous networks is studied in this paper. We propose a novel scalable video coding (SVC)-based two-tier cooperative caching strategy that can provide video services with different perceptual qualities. In addition, we propose a hierarchical hybrid transmission scheme where users obtain the requested layer files through the cooperative cellular multicast-D2D and THz transmissions. A base layer-based multicast group aggregation process is presented to improve resource utilization, while an efficient multicast transmission resource scheduling scheme can make better use of the spatial reusability. We derive the expressions for the average offloading capacity gain and average energy consumption, and formulate an efficiency function optimization problem. The problem is efficiently solved by the greedy strategy-gradient descent based caching solution and long tail distribution based heuristic caching solution. Simulation results validate the two solutions and demonstrate that the proposed caching-transmission method can achieve quasi-optimal performance compared with other contrasting schemes.

Transmission Energy Minimization for Heterogeneous Low-Latency NOMA Downlink

This paper investigates the transmission energy minimization problem for the two-user downlink with strictly heterogeneous latency constraints. To cope with the latency constraints and to explicitly specify the trade-off between blocklength (latency) and reliability the normal approximation of the capacity of finite blocklength codes (FBCs) is adopted, in contrast to the classical Shannon capacity formula. We first consider the non-orthogonal multiple access (NOMA) based transmission scheme. However, due to heterogeneous latency constraints and channel conditions at receivers, the conventional successive interference cancellation may be infeasible. We thus study the problem by considering heterogeneous receiver conditions under different interference mitigation schemes and solve the corresponding NOMA design problems. It is shown that, though the energy function is not convex and does not have closed form expression, the studied NOMA problems can be globally solved semi-analytically and with low complexity. Moreover, we propose a hybrid transmission scheme that combines the time division multiple access (TDMA) and NOMA. Specifically, the hybrid scheme can judiciously perform bit and time allocation and take TDMA and NOMA as two special instances. To handle the more challenging hybrid design problem, we propose a concave approximation of the FBC rate/capacity formula, by which we obtain computationally efficient and high-quality solutions. Simulation results show that the hybrid scheme can achieve considerable transmission energy saving compared with both pure NOMA and TDMA schemes.

A hybrid transmission scheme for networked control systems

Due to its obvious advantage on the efficient use of resources, the event-triggered mechanism is quickly applied in networked control systems (NCSs). However, when some event-triggered data packets are lost during network transmissions, it will become very challenging to analyse the NCSs since two consecutively event-triggered data are internally correlated and the relation will be destroyed when one of the data get lost. With the consideration, this paper proposes a hybrid communication mechanism for NCSs with data loss. Once a measurement that was event-triggered to be released got lost, the following measurements will be instantly transmitted to the controller. A networked controller is obtained for the NCS to guarantee the uniform ultimate boundedness of the system state. Finally, the validness and merits of the developed approach are illustrated through two well studied examples.

Toward Optimized Network Capacity in Emerging Integrated Terrestrial-Satellite Networks

In this paper, we investigate the transmission schemes of space data systems for optimized network capacity in an integrated terrestrial-satellite network (ITSN) with a two-layered space segment. First, a theoretical model of the network capacity is developed to evaluate the strategy of utilizing both direct and relayed transmissions. Second, we consider the ideal and the resource-constrained scenarios in which the corresponding network capacity is modeled with respect to the scheduling scheme. In particular, closed form and semi-closed form solutions to difficult integer programs are achieved via rigorous mathematical analysis. The proposed model is general for exploring the capacity of various satellite network deployments whose solutions have not been obtained in prior studies. Furthermore, we verify the potential capacity of the different transmission schemes based on the proposed solutions and prove that the system's network capacity can be significantly improved by the hybrid transmission scheme. The theoretical framework proposed in this paper is expected to provide constructive insights in the design for the future space segments of ITSNs.

A Hybrid Transmission Based Data Collection Scheme With Delay and Reliability Guaranteed for Lossy WSNs

Mobile computing provides new ways of data collection on the Internet of Things (IoT). The sensed environment information by various sensing devices could make access to a wireless sensor network (WSN) through access points and vice versa. Improving the energy efficiency for a prolonged network lifetime while meeting the adaptive performance requirements under the guarantees of transport delay and reliability is an important problem to be solved in data collection for lossy and large-scale wireless sensor networks (WSN). Although many previous studies devoted to improving the energy efficiency, reliability, or network delay, they mainly focus on one of the performance metrics of the WSN. In this paper, a hybrid transmission scheme integrating the packet reproduction (PR) and Hop-by-Hop Automatic Repeat-reQuest (HBH ARQ) schemes are proposed to improve energy efficiency and reduce delay under guarantee of reliability for the lossy WSN. In the proposed scheme, the network is divided into two parts by a hybrid boundary where the location information is used to help determine the routing changes between the PR and HBH ARQ schemes. Some key parameters involved in the scheme are discussed and analyzed. The effectiveness of the proposed scheme is evaluated via extensive simulation results.

Stackelberg Game for Distributed Time Scheduling in RF-Powered Backscatter Cognitive Radio Networks

In this paper, we study the transmission strategy adaptation problem in an RF-powered cognitive radio network, in which hybrid secondary users are able to switch between the harvest-then-transmit mode and the ambient backscatter mode for their communication with the secondary gateway. In the network, a monetary incentive is introduced for managing the interference caused by the secondary transmission with imperfect channel sensing. The sensing-pricing-transmitting process of the secondary gateway and the transmitters is modeled as a single-leader-multi-follower Stackelberg game. Furthermore, the follower sub-game among the secondary transmitters is modeled as a generalized Nash equilibrium problem with shared constraints. Based on our theoretical discoveries regarding the properties of equilibria in the follower sub-game and the Stackelberg game, we propose a distributed, iterative strategy searching scheme that guarantees the convergence to the Stackelberg equilibrium. The numerical simulations show that the proposed hybrid transmission scheme always outperforms the schemes with fixed transmission modes. Furthermore, the simulations reveal that the adopted hybrid scheme is able to achieve a higher throughput than the sum of the throughput obtained from the schemes with fixed transmission modes.

Hybrid Transmission Scheme for the Cluster Formation in Wireless Sensor Networks with Noisy Channels

Hybrid Transmission Scheme for the Cluster Formation in Wireless Sensor Networks with Noisy Channels

On Reconstructing Linear Combinations of Correlated Gaussian Sources Over a MAC

In this letter, we study the joint source-channel coding problem of communicating the linear functions of correlated Gaussian sources over a Gaussian multiple access channel. In this setup, each transmitter observes one of two correlated sources. The receiver aims to reconstruct a linear combination of both correlated Gaussian sources within an average distortion level. For this setup, we first obtain a new lower bound on the achievable distortion and then, we propose a novel lattice-based hybrid transmission scheme and its achievable distortion is derived. We show that our proposed scheme can achieve the optimal distortion under some conditions.

Hybrid Overlay/Underlay Transmission with Partial and Opportunistic Relay Selection in Cognitive Radio Networks

Objectives: In this paper, we consider a hybrid overlay/underlay strategy to maximize the throughput of primary users by use of idle secondary users as relays. Specifically, we focus on incorporating the advantageous features of underlay and overlay transmission methods into a hybrid cognitive radio technique. Analysis: By the use of the proposed technique both the primary and secondary users get benefited, as their communication link is uninterrupted. This scheme helps as an incentive for primary users to share their spectrum with the secondary users. Findings: The paper presents a resource allocation algorithm for the hybrid overlay/underlay transmission method. Also, the performance of the opportunistic and partial relay selection is investigated. This resource allocation algorithm is used to select the best channel from relay to destination, best relay and power allocated to best relay. Simulation results are presented to demonstrate the performance of the proposed hybrid technique over the traditional methods. The effectiveness of usage of the partial and opportunistic relay selection techniques is compared and the conclusions are drawn. Improvements: The proposed scheme will eliminate the need to switching between the overlay and underlay techniques. The resource allocation along with proposed hybrid transmission scheme will give significant improvement in SNR of primary user.

Joint Resource Allocation and Relay Selection in LTE-Advanced Network Using Hybrid Co-Operative Relaying and Network Coding

The problem of joint resource allocation and relay selection is studied for bidirectional LTE-advanced relay networks. The bidirectional communication between user equipment (UE) and eNodeB (eNB) is performed via direct transmission, co-operative relaying (CoR), or a combination of network coding (NC) and CoR (NC/CoR). In this paper, an enhanced three-time-slot per cycle time-division duplexing (TDD) scheme is proposed for LTE-Advanced frame architecture to accommodate a hybrid transmission scheme. More specifically, we formulate the problem of joint resource assignment, relay selection, and bidirectional transmission scheme selection as a combinatorial optimization problem with the objective to maximize the total product of backlog and rate (back-pressure principle). Two approaches are considered to solve our combinatorial optimization problem. First, a graph-based framework is proposed in which the problem is transformed into a maximum weighted Clique problem (MWCP). In addition, our problem is also transformed into a three-dimensional assignment problem (3DAP) which is solved using a hybrid ant colony optimization (ACO) algorithm. Using simulations, it is concluded that the hybrid transmission scheme outperforms all conventional nonhybrid schemes. Moreover, the simulation results confirm that while the two proposed solutions provide similar results, the ACO algorithm is faster due to its lower complexity.

Optimal Joint Resource Allocation and Power Control in Bidirectional Relaying Networks

Cooperative relaying (CoR) and network coding (NC) are two promising techniques for improving the performance of next-generation mobile networks. In this paper, a dynamic joint resource allocation and power control scheme is proposed for bidirectional relaying in wireless mobile networks. We consider a bidirectional relaying network consisting of three nodes: user equipment (UE), base station or eNodeB (eNB), and an intermediate relay station (RS). We model the network by a two-way relay channel (TWRC) in which UE and eNB can choose between different transmission schemes: direct transmission, pure CoR (CoR scheme), or via the combination of NC and CoR (NC/CoR scheme). We first study the achievable rate regions for direct transmission, CoR, and NC/CoR and characterize them by a set of linear inequalities. We show that NC/CoR does not always achieve better performance than CoR or direct transmission in terms of achievable throughput. Therefore, we propose a hybrid transmission scheme with adaptive resource allocation to dynamically choose the best transmission strategy and the optimal resource allocation at each bidirectional transmission time frame. This is done on the basis of the system channel state information and the buffer occupancy of UE and eNB. The hybrid approach achieves the convex hull of the union of the rate regions of the direct, CoR, and NC/CoR schemes. Finally, we extend our hybrid approach by considering power control at the RS, and we use simulations to study the effect of power control in the hybrid scheme. It is shown that in both single-input-single-output and multiple-input-multiple-output systems, the hybrid scheme with joint power control and resource allocation improves the throughput and delay performance of the system considerably.

Hybrid circuit-switched network for on-chip communication in large-scale chip-multiprocessors

Large-scale chip-multiprocessors (CMPs) need a scalable communication structure characterized by low cost, low power, and high performance to meet their on-chip communication requirements. This paper presents a hybrid circuit-switched (HCS) network for on-chip communication in the large-scale CMPs. The HCS network, which is Advanced Microcontroller Bus Architecture (AMBA) compatible, is composed of bufferless switches, pipeline channels, and network interfaces. Furthermore, packets are transferred in a hybrid transmission scheme. If a message has only one packet, the transmission scheme for this message is packet switching. Conversely, if a message contains multiple packets, the transmission scheme for this message is circuit switching. We evaluate HCS networks with different channel depths and then compare the HCS network with the Stanford elastic buffer (EB) network. Our results show that the HCS network with two-depth channel requires 83% less power and occupies 32% less area compared with the EB network. Furthermore, under maximum frequency and single traffic, the HCS network with two-depth channel provides 37% lower zero-load latency, 390% higher maximum throughput per unit power, and 19% higher maximum throughput per unit area compared with the EB network.

Capacity of multiple beamformed spatial stream transmission in millimetre‐wave communication channels

This study deals with the study on the performance of the hybrid transmission scheme combining both beamforming and spatial multiplexing for multiple spatial streams. The capacity of the hybrid scheme is evaluated and compared with that of the beamforming scheme for a single spatial stream in both line-of-sight and multi-path channels. Two kinds of hybrid schemes are considered: the shared antenna architecture, where each antenna processes all spatial streams and the split antenna architecture, where each antenna processes only one spatial stream. The effects of the channel parameters, such as the antenna spacing, the existence of reflected paths etc. On the capacity and the optimal beams and powers are examined. The frequency-selective property of the capacity and optimal beams and powers are also investigated. In this study, a scenario is assumed, where the same analogue radio frequency (RF) beamforming vector (or matrix) is applied to all subcarriers whereas the digital baseband power allocation is executed individually at each subcarrier.

Beam Selection and Antenna Selection: a Hybrid Transmission Scheme over MIMO Systems Operating with Vary Antenna Arrays

In this paper, we have proposed a hybrid transmission scheme which involves beam selection and antenna selection techniques over a MIMO system operating with vary antenna array. Optimal subset of transmit antennas are selected via fast successive selection scheme designed to optimize the target eigenbeam. Optimal eigenbeams corresponding to the largest singular values of the new MIMO channel formed by the selected antennas are exploited for data transmission. To evaluate the performance of the proposed scheme, different array structures, including uniform linear array (ULA) and including uniform circular array (UCA) are employed in the simulations. The transmitter is assumed to be surrounded by scattering objects while the receiver is postulated to be free from scattering objects. The Laplacian distribution of angle of arrival (AoA) of a signal reaching the receiver is postulated. The results presented by this paper indicate that the proposed scheme can significantly improve the performance of data transmission in term of symbol error rate (SER).

Hybrid Transmission Scheme for MIMO Relay Channels

To improve the achievable rate for the MIMO channel s, we propose a hybrid transmission (HT) scheme that mixes half-duplex decode-and-forward cooperative relaying transmission （ DFRH ） with direct transmission (DT). In the HT scheme, the source message is divided into two parts: one is transmitted by DFRH scheme and another is transmitted by DT scheme. Precoding and decoding are considered to convert the original MIMO relay channel into several parallel subchannels so that resource allocation can be easily performed . We focus on the spatial subchannel and power allocation problem . T he objective of this problem is to maximize the total achievable rate under the constraints of joint total transmission power . Simulation results show that significant capacity gain can be achieved by the HT scheme compared to t he DT scheme and the pure DFRH scheme.