全球6GHz频段规划情况分析

<正>无线电频谱作为稀缺的战略资源,是无线技术发展的基础。I M T（国际移动通信）系统及无线局域网（R L A N）系统的不断发展,以及数据业务量的不断增长,对可用频谱资源提出了更高需求。6G Hz频段（5925MHz～7125MHz）是中频频率的重要组成部分,兼顾了低频段的覆盖优势和高频段的容量优势,能够实现数千兆赫兹大带宽频谱连续分配,是广域大容量连接的最佳候选频段。以IMT系统为例,6GHz频段是对现有5G网络带宽的进一步扩展,可以满足多种不同场景需求。GSMA数据显示,截至2022年第一季度,     

基于层次化频谱需求预测的IMT系统频率规划

无线电频率规划是我国加快推进宽带无线移动通信产业发展的前提和基础,而频谱需求预测正是频率规划工作的关键所在。本文以ITU-R M.1768建议书提供的频谱需求预测方法为基础,利用博弈论和灰色预测等数学工具,提出全新的层次化频谱需求预测理念。在层次化预测中,首先根据我国市场数据,对我国IMT系统频谱总需求进行预测,然后根据我国运营商TDD和FDD技术体制的使用现状、发展策略,提出了精确量化的TDD和FDD方式频谱需求比例的预测结果 ,最后对我国IMT系统频谱规划提出参考性建议。     

一种IEEE 802.16无线网络的优化带宽调度策略

提出了一种基于预测的自适应实时轮询业务带宽分配机制:SS依据当前带宽需求和以往的实际分配带宽,对实时业务数据包所需求的确切带宽进行预测并调度.给出了数学分析模型和仿真,结果表明,与传统的带宽分配机制相比,该自适应的带宽分配算法能更好地改善系统性能,提高吞吐量,减少时延,减少缓冲区需求.     

面向业务的带宽预测及分配方法的研究

针对目前的带宽预测主要围绕聚合流量的问题,本文将IP网络承载业务分类,分析了数据、语音、视频等业务的特性及QoS需求,通过建立时延与缓存长度的映射关系,提出一种既满足业务流量的统计特性,又考虑不同业务的可容忍时延及丢失率的带宽预测及分配方法.这种预测及分配方法区分对待网络承载的业务,适用于细粒度的网络资源管理和流量控制.     

未来IMT系统频谱需求预测的现状与展望

为了满足下一代国际移动通信(IMT)系统的用频需求,实现频谱资源的科学分配和使用,避免超前分配导致的资源浪费,需要对其频谱需求总量做出合理预测,以支撑后续频谱规划与指配工作.对IMT频谱预测相关工作的现状进行了阐述,通过分析,对预测工作中的关键因素进行了归纳与总结,以期为后续工作提供借鉴.     

基于热点城区测算中国2020年移动通信频谱需求

提出了一种适合中国国情的频谱需求的预测方法。该预测方法充分借鉴了国际现有方法,可合理满足未来国际移动通信系统(IMT)的发展需求,实现频率资源的科学分配和使用,避免盲目规划导致的资源浪费。该预测方法从业务密集地区着手,通过调研运营商第一手数据,给出了更加精确的测算结果,可供中国运营商评估现有频谱使用情况、论证阶段频谱需求时使用。     

IMT-Advanced系统的频谱需求分析

文章依据ITU-R M.1768提供的频谱计算方法,通过预测远期移动用户及业务状况,估算了IMT-2000以及超IMT-2000系统未来发展对频谱资源的需求,同时得出2020年的频谱需求范围,为频谱资源的规划以及分配提供了依据,有效地提高了频谱资源的利用率.     

3G频率规划必将促进中国3G标准的产业化

国际3G频率规划1992年世界无线电行政大会(WARC)根据国际电联ITU-R对于第三代公众移动通信系统(IMT-2000)第一阶段业务量和所需频谱的估计，至少需要230MHz带宽，以及对各种因素的考虑，作出了下列频率规划：(1)1885～2025MHz及2110～2200MHz频带为全球基础上可用于IMT-2000的地面部分，初始实现期望在2000年开始；(2)上述频带中1980～2010MHz及2170～2200MHz部分(在区域2为1970～2010MHz及2160～2200MHz)为全球基础上从2005年开始可用于IMT-2000的卫星部分。简明情况见表1(MHz)地面卫星频带1885～20251980～2010带宽14030频…     

700 MHz NR共享频谱使用策略分析

本文针对700 MHz NR低频与大带宽的优势,基于建网初期5G网络利用率低,同时4G网络利用率高的情况,探讨NR与LTE在同一频谱上根据业务量需求进行时频资源的瞬时动态频谱共享与灵活的功率分配的方法,以及NR与LTE小区共享同一段频谱资源时对上下行物理信道资源进行合理协调调度来规避冲突并提升频谱使用效率的方案,保障N...     

多种无线制式的网络容量规划

随着LTE网络的大规模建设,2G/3G和LTE网络将在一定时期内长期并存。对各种制式的网络容量进行协调规划,首先需要对各种制式的网络配置数据和参数进行分析;其次是预测不同类型业务量的增长和网络负荷情况;最后,基于不同的驱动环境制定容量规划方案。本文总结了基于市场驱动、覆盖、容量和无线频谱等场景的容量规划方法。基于市场驱动的容量规划,网络为市场服务,业务需求预测成为对网络容量规划的依据;基于覆盖驱动的容量规划,首先满足覆盖要求,分步建站,逐步提高系统容量;基于容量驱动的容量规划,需要满足用户的服务质量要求,用户的业务需求和服务质量等级成为容量规划的依据;基于无线频谱的容量规划,需要在不同制式系统之间合理分配容量,以达到频率效率最优。     

Bandwidth Reallocation for Bandwidth Asymmetry Wireless Networks Based on Distributed Multiservice Admission Control

This paper addresses when and how to adjust bandwidth allocation on uplink and downlink in a multi-service mobile wireless network under dynamic traffic load conditions. Our design objective is to improve system bandwidth utilization while satisfying call level QoS requirements of various call classes. We first develop a new threshold-based multi-service admission control scheme (DMS-AC) as the study base for bandwidth re-allocation. When the traffic load brought by some specific classes under dynamic traffic conditions in a system exceeds the control range of DMS-AC, the QoS of some call classes may not be guaranteed. In such a situation, bandwidth re-allocation process is activated and the admission control scheme will try to meet the QoS requirements under the adjusted bandwidth allocation. We explore the relationship between admission thresholds and bandwidth allocation by identifying certain constraints for verifying the feasibility of the adjusted bandwidth allocation. We conduct extensive simulation experiments to validate the effectiveness of the proposed bandwidth re-allocation scheme. Numerical results show that when traffic pattern with certain bandwidth asymmetry between uplink and downlink changes, the system can re-allocate the bandwidth on uplink and downlink adaptively and at the same time improve the system performance significantly.     

Bandwidth utilization efficiency enhancement for OFDM‐based WSN

Normally IEEE 802.16 (WiMAX) is used for mainly downlink traffic applications. However in the upper tier of 2‐tier (WiMAX‐WiFi) wireless sensor network, the uplink bandwidth faces bottlenecks for high throughput. In this paper, a solution has been proposed for this limitation of uplink bandwidth allocation through the use of queuing theoretic performance modeling. A Markov‐modulated Poisson process traffic model has been formed for orthogonal frequency division multiple access‐based transmission along with discrete time Markov chain system model for queuing. A downlink traffic pattern has been defined for wireless sensor network nodes. Analytical methods are used to estimate the performance parameters like throughput, delay, and probability of packet drop for resource allocation. An algorithm is formulated to find out minimum resource requirement for downlink and to transfer rest of the resources to uplink bandwidth allocation, for throughput enhancement. Uplink frame utilization is determined through another discrete time Markov chain model for adaptive triggering between the proposed maximum and the normal downlink to uplink ratio operations, for efficient distribution of bandwidth resources. Algorithm and simulation results prove outstanding improvement in the uplink throughput around 50%, without degrading the downlink throughput.     

TD-LTE容量能力综合分析

明确分析了影响TD-LTE容量能力的相关因素。在此基础上,提出TD-LTE系统容量的评估指标,然后对其上下行业务信道和控制信道的容量进行了细致和针对性的分析,对包括最大可同时调度用户数、VoIP容量、小区峰值吞吐量和小区平均吞吐量等指标给出了具体的计算模型和方法。针对20MHz的系统带宽,给出了TD-LTE容量的计算案例,非常有利于解决今后网络规划中的容量建模问题。     

Optimal Bandwidth Assignment on Up- and Downlinks of Satellite with Buffer Capacity

This paper considers a satellite communication system with the slotted ALOHA access mode where the satellite is assumed to have on-board regeneration ability and the finite buffer capacity for storing noncollided packets from the uplink. The system is analyzed with the downlink bandwidth restricted to1/Lof the uplink bandwidth, and with the conventional slotted ALOHA system whereL = 1and the buffer size at the satellite is equal to zero. Maximum throughput and throughput-delay characteristics of this system are analytically obtained. The satellite is given an optimal buffer size to achieve maximum throughput and minimum packet transmission delay. It is shown that the constraints that lead to the downlink bandwidth being lower than the uplink bandwidth do not necessarily result in throughput penalties in a buffered satellite system. Furthermore, when the total bandwidth which can be divided between up- and downlinks is given, if two or three times that of the downlink is assigned to the uplink and if the satellite has buffer storage space only for a few packets, we show that maximum throughput of the system will be improved about 40 percent with little change in delay characteristics in comparison with that of the conventional slotted ALOHA system where the given total bandwidth is equally divided between up- and downlinks.     

Single-Fiber Access/Metro WDM Ring Architecture for Asymmetric Traffic Applications in Next Generation Networks

The next generation network (NGN) and the speed-up of access lines will sharply increase the demand for one-way applications such as internet protocol television (IP TV) and video on demand (VOD). One-way applications make the downlink bandwidth much larger than the uplink bandwidth. Asymmetric traffic is best supported by using different numbers of wavelengths in the uplink and downlink, which presumes the use of a wavelength division multiplexing (WDM) network. Unfortunately, the existing 2- or 4-fiber ring network architecture is symmetric, and so it cannot efficiently accommodate asymmetric paths. This paper proposes a novel 1-fiber WDM protection ring that offers a cost-effective optical network architecture for asymmetric traffic as well as symmetric traffic. It also proposes a new 1:1 protection switching scheme and automatic protection switching (APS) control protocol that can reduce capital expenditures for optical-electro-optical termination cards and provide nonrevertive protection switching with extra traffic and APS with end-to-end supervision including optical switching fabrics. Moreover, this paper shows that the proposed wavelength switching scheme offers much better network survivability after multiple wavelength failures than the existing bidirectional switching scheme can offer.     

面向高流量家宽业务的接入网演进策略研究

随着高清网络电视、3D视频等新兴业务的发展,用户对接入带宽的需求越来越高。针对高流量业务对接入网的需求变化,本文分析了现网存在的问题,测算了不同场景下接入网的承载能力,提出应对宽带提速的接入网络演进策略：OLT下行策略和OLT上联部署策略。本文所提策略能够有效指导运营商在面对用户流量高增长的形势下及时调整接入网络结构,为用户提供更好的网络体验。     

Novel detector implementations for 3G LTE downlink and uplink

We summarize our recent state-of-the-art programmable and reconfigurable detector and QR decomposition (QRD) implementations targeting 3G long term evolution (LTE) downlink and uplink requirements. The downlink transmission is based on the orthogonal frequency division multiplexing, whereas the uplink transmission uses a single-carrier frequency-division multiple access. The downlink implementations are based on the programmable transport triggered architecture (TTA) which provides a flexible and energy efficient architecture template. In TTA detector implementation, the LTE detection rate requirements up to 20 MHz bandwidth and 4 × 4 antenna system with 64-QAM, are achieved by using 1–6 programmable cores in parallel. Each core runs at 277 MHz clock frequency and consumes 55.5–64.0 mW depending on the detector configuration. The downlink detector is based on the selective spanning with fast enumeration algorithm. The uplink field-programmable gate array (FPGA) detector implementation is targeted for 4 × 4 antenna system and 64-QAM achieving a detection rate requirement for 20 MHz bandwidth. The used FPGA board for uplink implementation is Xilinx Virtex-6 and the implementation has been carried out using Xilinx Vivado high level synthesis tool. Two different detector architectures are implemented. The first one achieves the detection rate requirement with a single processing block running at 231 MHz and the latter one with four blocks in parallel, each running at 247 MHz. The implemented detector is based on the K-best algorithm. A multiple-input multiple-output receiver requires QRD to produce valid inputs for the detector. In addition to detector implementations, QRD is also implemented on both TTA and FPGA. Modified Gram–Schmidt algorithm is used in both QRD implementations.     

iVoIP: an intelligent bandwidth management scheme for VoIP in WLANs

Voice over Internet Protocol (VoIP) has been widely used by many mobile consumer devices in IEEE 802.11 wireless local area networks (WLAN) due to its low cost and convenience. However, delays of all VoIP flows dramatically increase when network capacity is approached. Additionally, unfair traffic distribution between downlink and uplink flows in WLANs impacts the perceived VoIP quality. This paper proposes an intelligent bandwidth management scheme for VoIP services (iVoIP) that improves bandwidth utilization and provides fair downlink–uplink channel access. iVoIP is a cross-layer solution which includes two components: (1) iVoIP-Admission Control, which protects the quality of existing flows and increases the utilization of wireless network resources; (2) iVoIP-Fairness scheme, which balances the channel access opportunity between access point (AP) and wireless stations. iVoIP-Admission Control limits the number of VoIP flows based on an estimation of VoIP capacity. iVoIP-Fairness implements a contention window adaptation scheme at AP which uses stereotypes and considers several major quality of service parameters to balance the network access of downlink and uplink flows, respectively. Extensive simulations and real tests have been performed, demonstrating that iVoIP has both very good VoIP capacity estimation and admission control results. Additionally, iVoIP improves the downlink/uplink fairness level in terms of throughput, delay, loss, and VoIP quality.     

CDMA/TDD system for wireless multimedia services with trafficunbalance between uplink and downlink

This paper proposes a code division multiple access (CDMA) time division duplex (TDD) system for wireless multimedia services with traffic unbalance between uplink and downlink. In the proposed system, the number of uplink time slots in a TDD frame differs from that of downlink. Moreover, the difference can be reset by the network operator according to the traffic pattern. We evaluate the performance of the proposed system under multimedia environment using Markov analysis and computer simulation. The results show that the frequency utilization is maximized even when the uplink and downlink traffic volumes are unbalanced. This, in turn, reduces drastically the blocking rate of multimedia calls (connections) in the proposed system compared with that in the traditional CDMA systems where the uplink and downlink use equal bandwidth     

A bandwidth allocation algorithm with channel quality and QoS aware for IEEE 802.16 base stations

Subscriber stations located in different places encounter various interferences in an IEEE 802.16 network, resulting in that their communication channels experience varying channel conditions. Thus, an excellent bandwidth allocation algorithm should not only satisfy various QoS required by heterogeneous traffic, but also consider the channel quality to maximize bandwidth utilization. In this paper, a bandwidth allocation algorithm with channel quality awareness and QoS guarantee, called CQQ, is proposed. CQQ not only satisfies each connection's QoS requirement, but also dynamically adjusts the downlink/uplink bandwidth to match current downlink/uplink traffic ratio. CQQ allocates more bandwidth to the connections having better channel quality by applying weighted fair queuing strategy to raise the bandwidth usage. CQQ provides lower delay violation ratio and higher goodput than the previous algorithms, as observed from the simulation results. Copyright © 2012 John Wiley & Sons, Ltd.