Coordinated Transmission Scheme Research Articles

Clustered NOMA-based downlink adaptive relay coordinated transmission scheme for future 6G cell-free edge network

Clustered NOMA-based downlink adaptive relay coordinated transmission scheme for future 6G cell-free edge network

Secure NOMA and OMA coordinated transmission schemes in untrusted relay networks

Secure NOMA and OMA coordinated transmission schemes in untrusted relay networks

Novel Multi-AP Coordinated Transmission Scheme for 7th Generation WLAN 802.11be.

The demand for high-data-rate and time-sensitive applications, such as 4k/8k video streaming and real-time augmented reality (AR), virtual reality (VR), and gaming, has increased significantly. Addressing the inefficiency of distributed channel access and the fairness problem between uplink and downlink flows is crucial for the development of wireless local area network (WLAN) technologies. In this study, we propose a novel transmission scheme for IEEE 802.11be networks that addresses the fairness problem and improves the system throughput. Utilizing the concept of multi-AP coordinated OFDMA introduced in the 7th-generation WLAN IEEE 802.11be, the proposed transmission scheme allows an AP to share a granted transmission opportunity (TXOP) with nearby APs. A mathematically analysis of the throughput performance of the proposed schemes was performed using a Markov chain model. The simulation results verify that the scheme effectively improves the downlink fairness and the system throughput. Combined with the advanced multiuser (MU) features of IEEE 802.11ax, such as TUA, MU cascading sequence, and MU EDCA, the proposed scheme not only enhances downlink AP transmission, but also guarantees improved control over the medium. The scheme is carefully designed to be fully compatible with conventional IEEE 802.11 protocols, and is thus potentially universal.

Cache-Enabled Coordinated Mobile Edge Network: Opportunities and Challenges

Cache-enabled coordinated mobile edge network is an emerging network architecture, wherein serving nodes located at the network edge have the capabilities of baseband signal processing and caching files at their local cache. The main goals of such an emerging network architecture are to alleviate the burden on fronthaul links, while achieving low-latency high rate content delivery, say on the order of the millisecond level end-to-end content delivery latency. Consequently, the application of delay-sensitive and content-aware has been executed in close proximity to end users. In this article, an outlook of research directions, challenges, and opportunities is provided and discussed in depth. We first introduce the cache-enabled coordinated mobile edge network architecture, and then discuss the key technical challenges and opening research issues that need to be addressed for this architecture. Then, to reduce the delivery latency and the burden on fronthaul links, new cache-enabled physical layer transmission schemes are discussed. Finally, artificial intelligence based cache-enabled communications are discussed as future research directions. Numerical studies show that several gains are achieved by caching popular content at the network edge with proper coordinated transmission schemes.

Applying Multiradio Access Technologies for Reliability Enhancement in Vehicle-to-Everything Communication

The design of the 5G cellular network should take account of the emerging services with divergent quality of service requirements. For instance, a vehicle-to-everything (V2X) communication is required to facilitate the local data exchange and therefore improve the automation level in automated driving applications. In this paper, we inspect the performance of two different air interfaces (i.e., LTE-Uu and PC5) which are proposed by the third generation partnership project to enable the V2X communication. With these two air interfaces, the V2X communication can be realized by transmitting data packets either over the network infrastructure or directly among traffic participants. In addition, the ultra-high reliability requirement in some V2X communication scenarios cannot be fulfilled with any single transmission technology (i.e., either LTE-Uu or PC5). Therefore, we discuss how to efficiently apply multi-radio access technologies (multi-RAT) to improve the communication reliability. In order to exploit the multi-RAT in an efficient manner, both the independent and the coordinated transmission schemes are designed and inspected. Subsequently, the conventional uplink is also extended to the case where a base station can receive data packets through both the LTE-Uu and PC5 interfaces. Moreover, different multicast-broadcast single-frequency network area mapping approaches are also proposed to improve the communication reliability in the LTE downlink. Last but not least, a system level simulator is implemented in this paper. The simulation results do not only provide us insights on the performances of different technologies but also validate the effectiveness of the proposed multi-RAT scheme.

Cooperative Channel Estimation for Coordinated Transmission With Limited Backhaul

Obtaining accurate global channel state information (CSI) at multiple transmitter devices is critical to the performance of many coordinated transmission schemes. Practical CSI local feedback often leads to noisy and partial CSI estimates at each transmitter. With rate-limited bi-directional backhaul, transmitters have the opportunity to exchange few CSI-related bits to establish global channel state information at transmitter (CSIT). This paper investigates possible strategies toward this goal. We propose a novel decentralized algorithm that produces minimum mean square error-optimal global channel estimates at each device from combining local feedback and information exchanged through backhauls. The method adapts to arbitrary initial information topologies and feedback noise statistics and can do that with a combination of closed-form and convex approaches. Simulations for coordinated multi-point transmission systems with two or three transmitters exhibit the advantage of the proposed algorithm over conventional CSI exchange mechanisms when the coordination backhauls are limited.

Energy efficient coordinated transmission scheme for multi-cell distributed antenna systems

Energy efficient coordinated transmission scheme for multi-cell distributed antenna systems

Coordinated Shared Spectrum Precoding With Distributed CSIT

In this paper, the operation of a licensed shared access system is investigated, considering downlink communication. The system comprises a multiple-input-single-output (MISO) incumbent transmitter (TX)–receiver (RX) pair, which offers a spectrum sharing opportunity to a MISO licensee TX-RX pair. Our main contribution is the design of a coordinated transmission scheme, inspired by the underlay cognitive radio (CR) approach, with the aim of maximizing the average rate of the licensee, subject to an average rate constraint for the incumbent. In contrast to most prior works on the underlay CR, the coordination of the two TXs takes place under a realistic channel state information (CSI) scenario, where each TX has solely access to the instantaneous direct channel of its served terminal. Such a CSI knowledge setting brings about a formulation based on the theory of Team Decisions, whereby the TXs aim at optimizing a common objective given the same constraint set, on the basis of individual channel information. Consequently, a novel set of applicable precoding schemes consisting in letting the two TXs cooperate on the basis of the statistical information is proposed. We verify by simulations that this novel, practically relevant, coordinated precoding scheme outperforms the standard underlay CR approach.

Analysis of the Throughput of the Cellular Radio-Communication Systems Using Coordinated Data Transmission to Suppress Mutual Unintended Interference

We present the results of the comparative analysis of two data-transmission schemes of the fourth-generation cellular communication standard LTE-A, which use the “quasistatic” and “dynamic” coordination at the neighbor base stations. Both schemes are used to suppress mutual unintended co-channel interference resulting from the repeated use of one frequency channel by the neighbor base stations. The general case of the heterogeneous cellular radio-communication system with different station types (macro- and picostations) is considered. In this work, the efficiency of the coordinated-transmission schemes is studied along with the adaptive algorithms for the dataflow planning and control. The use of both coordination schemes is comparatively analyzed. An original algorithm for redistribution of the user connections is proposed for the dynamic scheme and the dependence of the communication-system throughput on the radio-network configuration and the number of base stations, that participate in the coordination is studied.

Block diagonalization coordinated transmission with zero-forcing in MIMO broadcast

This work has investigated coordinated multiple-input multiple-output (MIMO) transmission schemes in an interference-limited cellular downlink. It has proposed a novel block diagonalization (BD) coordinated transmission scheme, which combines with zero-forcing (ZF) criterion. In the scheme, the BD technique has advantages in suppressing multi-user interference while the ZF technique enables to mitigate interference among spatial data streams for a user. Based on the proposed coordinated scheme, an efficient power allocation is also put forward. The analyses show that the ergodic capacity of the proposed coordinated scheme is that of the MIMO channel with the maximum transmit power at each transmitter. Computer simulations demonstrate the effectiveness of the proposed coordinated scheme and its corresponding power allocation.

Research on uplink coordinated transmission schemes in LTE-advanced systems

The investigation of inter-cell interference mitigation techniques is a key area in wireless communications. Coordinated multiple points (CoMP) transmission/reception is a candidate technique for interference cancellation in 3GPP LTE-Advanced system. However, the coordination scheme in CoMP remains a key research problem to be solved, which will have a strong influence on the performance of CoMP. In this paper, a novel coordinated transmission scheme is proposed for the uplink LTE-Advanced system. In our scheme, several base transceiver stations (BTS) and users are selected as coordination partners which form a CoMP cluster. Joint processing is used at the receiver to mitigate interference. From the perspective of coordinated partner selection, our scheme can be divided into static and dynamic coordination which are both considered to fully exploit the throughput gain of CoMP. The proposed schemes are evaluated by system level simulation and compared with the conventional LTE system based upon single cell processing. Our simulation results demonstrate that the proposed schemes attain superior performance as opposed to the conventional system in terms of cell average and cell edge throughput.