Uplink CFO compensation for FBMC multiple access and OFDMA in a high mobility scenario

We study in this work CFO compensation methods for two multicarrier multiple access techniques in a high mobility scenario. In particular, we consider orthogonal frequency division multiple access (OFDMA) and filter bank multicarrier multiple access (FBMC-MA). The main motivation for this study is not only the different sensitivity these multicarrier techniques have to CFO but also the different methods they use to reduce CFO effect. In a high mobility scenario the CFO is re-estimated to follow its variation. We show that the frequency at which the CFO is re-estimated has a strong influence in the performance and the complexity of the proposed compensation methods. Additionally, we present a low-complexity CFO compensation method for OFDMA that employs a better approximation of the intercarrier interference than previous approaches. Regarding FBMC-MA, we introduce an extension of a CFO-compensation method that allows to consider a multitap channel equalizer. Finally, using simulations, we compare the performance of the compensation methods over several channel and time-varying CFO conditions.     

OFDMA-based LAN emulation in long-reach hybrid PON system

A novel long-reach, hybrid wavelength-division multiplexing (WDM) and time-division multiplexing (TDM) passive optical network (PON) architecture which supports local area network (LAN) emulation among customers is proposed. Orthogonal frequency division multiplexing access (OFDMA) technology is used in optical network units (ONUs) to transmit the LAN data. The optical LAN data from an ONU is converted into the electrical signal and combined with TDM downstream access data in the extended box for delivery to other ONUs. This scheme has many advantages on LAN emulation, such as dynamic allocation of LAN bandwidth, no bandwidth cost of TDM business, supporting multiple concurrent LAN services and so on. Simulations are performed to verify the scheme. Tolerance of dispersion and factors that influence the performance of various independent services are all investigated and analyzed.     

Enhancement in Quality-of-Services using 5G cellular network using resource reservation protocol

Mobile verbal exchange is viewed as one of the essential problem in the area of cellular networks. A mobile community apparatuses the proper public model to contribute packet of the data services on excessive speed. The packets of data service model are mandatory to improve the quality of service (QoS). This lookup exertion offers the Improvement of QoS and radio get right of entry to 5G Mobile Networks. Towards improve built-in services, a useful resource allocation protocol is applied at “Radio Access Network (RAN)” layer to improve the QoS in 5G. QoS labeling is a form of organizational communication that enables a local hub or exit station to communicate with or signal its neighbors to request special adjusting to of favorable traffic. QoS highlighting is helpful to provide ways for site visitors to adjust. ISP perform well and show full potential of the pervasive network by utilizing the simulation model in 5G’s ultra-low latency, real-time connectivity, significantly increased capacity, and quick speed. This will help to make device connections faster, more efficient, and less prone to delays. Lower, medium, and high frequency bands can be used to categories 5G. Mid-bandwidth enables better cell broadband connections or greater machine-to-machine communication and provides faster connectivity than 4G at close range.     

OFDMA网络中基于用户协作的负载均衡机制

在蜂窝小区中,利用用户在不同小区之间的切换实现负载均衡可以提高系统频率利用率,减小用户中断率。但是,高负载小区的边缘用户切换到低负载小区时信噪比会降低。提出了一种基于用户协作的负载均衡机制,在均衡小区间负载的同时,解决了小区边缘用户切换后信噪比降低的问题。所提机制中,轻负载小区的某个用户作为中继节点与重负载小区的被切换用户进行协作通信。被切换的边缘用户通过选择合适的"用户中继",保证了切换后的信噪比性能。推导了选择用户作为中继的必要条件,提出了最大化系统容量的用户中继选择方案。数值仿真结果表明,所提机制可以有效的提高被切换用户的吞吐量,从而证明被切换用户的信噪比性能没有损失。     

A contemporary review on user scheduling techniques and feedback reduction strategies towards the development of 5G and beyond communications

User scheduling (US) is the process of dynamic selection of the set of active users out of all available users to serve in each time slot. This is done to optimize the system performance, such as maximizing the sum rate, achieving better fairness, and quality of service or minimizing the interference. The choice of US method depends on the desired system performance and the trade-off between fairness and efficiency. In order to achieve these performance metrics base station (BS) needs channel state information (CSI) of each user for efficient US. Moreover, US and CSI feedback are closely related in the context of conventional multiple-input multiple-output (MIMO) to massive MIMO (mMIMO) systems based on full and limited CSI, as feedback information is often used to make informed decisions on US. To address these objectives simultaneously, this survey deals with exploring different algorithms used for efficient US, various criteria for US considering different scenarios, key methods for user grouping, methods for reduced feedback, and different standard codebook based feedback methods. To be more specific and concise, this article provides a comprehensive survey on state of the art methods used for US in single cell single tier, dual stage (double tier), multi cell scenarios and feedback mechanisms used in various contexts, e.g., multiuser (MU)-MIMO, MU-mMIMO, frequency division duplexing (FDD) mMIMO framework. Moreover, a synopsis of the recently proposed advanced codebook and non-codebook based methods for the long term evolution standards, fifth generation, and beyond communications are discussed. Finally the research gaps as the future scopes are discussed in this article.     

利用OFDMA进行资源分配的投机算法

正交频分复用OFDM(Orthogonal Frequency Division Multiplexing)系统以其优良的对抗频率选择性衰落和信号码间串扰的能力,被看作是Beyond 3G移动通信的主要技术.IEEE802.16工作组将OFDM和OFDMA(Orthogonal Frequency Division Multiple Accessing)作为802.16d/e的物理层选择.802.16e重点采用OFDMA来保证移动性,它的物理层可以支持四种不同的子载波数量,信号带宽与子载波数量成正比,这就可以在移动环境中灵活适应信道带宽的变化.本文对单蜂窝系统中下行链路的资源分配(包括子载波的分配和功率的分配)进行了研究探讨,提出了一个投机算法,目的是最大化系统的瞬时数据吞吐量.