59 research outputs found
The Research and FPGA Implementation of WCDMA Interference Cancellation Repeater
随着无线通信技术的快速发展,直放站由于其低投入、低成本、较短的建设周期和较好的网络质量等优点,已经被广泛用于无线网络中的扩展覆盖区和填补信号弱区盲区。但直放站应用的一大缺陷是严重的同频干扰,本文将自适应干扰抵消技术应用到WCDMA无线直放站,正是为了减小同频干扰造成的自激。 本文首先简单概述了几种常用的自适应干扰抵消算法,并对算法性能进行了Matlab仿真,结合算法收敛速率和算法计算复杂度,以及信号实时高速处理的需要,本文选择了DLMS算法作为AIC直放站的干扰抵消算法。其次详细介绍和仿真了基于CAZAC序列的AIC直放站,且将重定时技术引入到DLMS滤波器结构变换中,对插入的延时进行重分配...As wireless communication technology developing, for the good characteristics of low-input, low operating cost, relatively short construction period and good network quality, the repeater, as an effective radio signal transmission and amplification device, has been widely used to expand the networks and fill the blind area. However, the feedback oscillation is always a weakness in engineering appl...学位:工学硕士院系专业:信息科学与技术学院通信工程系_通信与信息系统学号:2332009115280
The Research and Implementation of the Adaptive Interference Cancellation in WCDMA Repeater
直放站是一种中继设备,在已经到来的3G时代依旧需要其协助基站来扩大信号的覆盖范围。无线直放站在应用中常会因为收发天线间隔离度不高而引发严重的干扰问题,本论文应用自适应干扰抵消技术对WCDMA无线直放站的同频干扰进行抵消,进而提高WCDMA直放站的性能,方便其使用。 本文首先对WCDMA直放站中存在的干扰进行分析,说明了使用自适应滤波进行干扰抵消的必要性。根据自适应干扰抵消应用的原理,结合直放站干扰环境,确定了WCDMA直放站下的自适应干扰抵消方案。 本文在自适应干扰抵消算法的性能以及成本比较后,选择了适合硬件实现的DLMS算法来实现关键的自适应滤波模块。为了提高FPGA上实现的自适应干扰抵...Repeater is a type of relaying equipment and can be used to provide wider coverage. In the age of 3G, repeater is still widely used. Repeater always be disturbed by a serious feedback interference that comes into the receive antenna from the transmit antenna of the repeater. In this paper, adaptive interference cancellation technology is implemented in WCDMA repeater to cancel the inherent co-chan...学位:工学硕士院系专业:信息科学与技术学院通信工程系_通信与信息系统学号:2332008115329
Indoor Radio Measurement and Planning for UMTS/HSPDA with Antennas
Over the last decade, mobile communication networks have evolved tremendously with a key focus on providing high speed data services in addition to voice. The third generation of mobile networks in the form of Universal Mobile Telecommunications System (UMTS) is already offering revolutionary mobile broadband experience to its users by deploying High Speed Downlink Packet Access (HSDPA) as its packet-data technology. With data speeds up to 14.4 Mbps and ubiquitous mobility, HSDPA is anticipated to become a preferred broadband access medium for end-users via mobile phones, laptops etc. While majority of these end-users are located indoors most of the time, approximately 70-80% of the HSDPA traffic is estimated to originate from inside buildings. Thus for network operators, indoor coverage has become a necessity for technical and business reasons.
Macro-cellular (outdoor) to indoor coverage is a natural inexpensive way of providing network coverage inside the buildings. However, it does not guarantee sufficient link quality required for optimal HSDPA operation. On the contrary, deploying a dedicated indoor system may be far too expensive from an operator\u27s point of view. In this thesis, the concept is laid for the understanding of indoor radio wave propagation in a campus building environment which could be used to plan and improve outdoor-to-indoor UMTS/HSDPA radio propagation performance. It will be shown that indoor range performance depends not only on the transmit power of an indoor antenna, but also on the product\u27s response to multipath and obstructions in the environment along the radio propagation path.
An extensive measurement campaign will be executed in different indoor environments analogous to easy, medium and hard radio conditions. The effects of walls, ceilings, doors and other obstacles on measurement results would be observed.
Chapter one gives a brief introduction to the evolution of UMTS and HSDPA. It goes on to talk about radio wave propagation and some important properties of antennas which must be considered when choosing an antenna for indoor radio propagation. The challenges of in-building network coverage and also the objectives of this thesis are also mentioned in this chapter.
The evolution and standardization, network architecture, radio features and most importantly, the radio resource management features of UMTS/HSDPA are given in chapter two. In this chapter, the reason why Wideband Code Division Multiple Access (WCDMA) was specified and selected for 3G (UMTS) systems would be seen. The architecture of the radio access network, interfaces with the radio access network between base stations and radio network controllers (RNC), and the interface between the radio access network and the core network are also described in this chapter. The main features of HSDPA are mentioned at the end of the chapter.
In chapter three the principles of the WCDMA air interface, including spreading, Rake reception, signal fading, power control and handovers are introduced. The different types and characteristics of the propagation environments and how they influence radio wave propagation are mentioned. UMTS transport, logical and physical channels are also mentioned, highlighting their significance and relationship in and with the network.
Radio network planning for UMTS is discussed in chapter four. The outdoor planning process which includes dimensioning, detailed planning, optimization and monitoring is outlined. Indoor radio planning with distributed antenna systems (DAS), which is the idea and motivation behind this thesis work, is also discussed.
The various antennas considered and the antenna that was selected for this thesis experiment was discussed in chapter five. The antenna radiation pattern, directivity, gain and input impedance were the properties of the antenna that were taken into consideration. The importance of the choice of the antenna for any particular type of indoor environment is also mentioned.
In chapter six, the design and fabrication of the monopole antennas used for the experimental measurement is mentioned. The procedure for measurement and the equipment used are also discussed. The results gotten from the experiment are finally analyzed and discussed. In this chapter the effect of walls, floors, doors, ceilings and other obstacles on radio wave propagation will be seen.
Finally, chapter seven concludes this thesis work and gives some directions for future work
Indoor Planning in Broadband Cellular Radio Networks
The capacity requirements of cellular networks continue to grow. This has forced cellular operators to seek new ways of improving the availability and transmission rate experienced by users. The majority of cellular network data users are located inside buildings, where coverage is difficult to ensure due to high penetration loss. Indoor users also cause high load to outdoor networks, reducing the quality and availability for outdoor users. This has given rise to a growing need for implementing dedicated indoor systems, and further optimizing their performance to provide high capacity.
It was estimated that in 2011 there were 5.37 billion mobile subscriptions in 3GPP-supported GSM, UMTS/HSPA and LTE networks, of which 890.7 million were using UMTS/HSPA. Currently, UMTS is the leading standard for providing mobile broadband, although LTE is becoming increasingly popular. The planning of radio networks is well known and documented. However, the planning and optimization of indoor networks has not been widely studied, although clear improvements in both coverage and capacity can be achieved by optimizing cell- and antenna line configuration.
This thesis considers the special characteristics of the indoor environment with regard to radio propagation and radio network planning. The aspects of radio network planning are highlighted especially for WCDMA radio access technology. The target is to provide guidelines for indoor radio network planning and optimization using an outdoor-to-indoor repeater or a dedicated indoor system with various antenna and cell configurations. The studies conducted here are intended to provide better understanding of the indoor functionality and planning of WCDMA radio access, and UMTS cellular system including the latest HSPA updates.
The studies show that the indoor performance of a high data rate WCDMA system can be improved by increasing the antenna density in the distributed antenna system, or by utilizing uplink diversity reception. It is also shown how system capacity can be further improved by adding more indoor cells to a single building. The inter-cell interference is analyzed, and the limits for cell densification are discussed.
The results show that compared to dedicated indoor systems, similar indoor performance can be provided by extending macrocellular coverage inside buildings using an outdoor-to-indoor repeater. However, good performance of repeater implementation needs careful repeater antenna line and parameter configuration. Nevertheless, capacity is in any case borrowed from an outdoor mother cell.
Sharing frequencies between outdoor and indoor systems is often necessary due to high capacity demand and limited available frequency band. A co-channel indoor system was measured to affect both uplink and downlink performance of an outdoor cell. In the uplink, a clear increase in uplink intercell interference was observed. Throughput degradation was also measured in downlink, but the affect is limited to the area close to the indoor system. However, the added high capacity of an indoor network usually justifies performance degradation.
The results can help mobile operators design their networks to provide better coverage, higher capacity and better quality for indoor users. After taking into account the implementation costs, the results also help operators to reach a techno-economic trade-off between the various deployment options
Design And Analysis Of Modified-Proportional Fair Scheduler For LTELTE-Advanced
Nowadays, Long Term Evolution-Advanced (LTE-Advanced) is well known as a cellular network that can support very high data rates in diverse traffic conditions. One of the key components of Orthogonal Frequency-Division Multiple Access (OFDMA), Radio Resource Management (RRM), is critical in achieving the desired performance by managing key components of both PHY and MAC layers. The technique that can be done to achieve this is through packet scheduling which is the key scheme of RRM for LTE traffic processing whose function is to allocate resources for both frequency and time dimensions. Packet scheduling for LTE-Advanced has been a dynamic research area in recent years, because in evidence, the increasing demands of data services and number of users which is likely to explode the progress of the LTE system traffic. However, the existing scheduling system is increasingly congested with the increasing number of users and requires the new scheduling system to ensure a more efficient data transmission. In LTE system, Round Robin (RR) scheduler has a problem in providing a high data rate to User Equipment’s (UEs). This is because some resources will be wasted because it schedules the resources from/ to UEs while the UEs are suffering from severe deep fading and less than the required threshold. Meanwhile, for Proportional Fair (PF) scheduler, the process of maximizing scheme of data rate could be very unfair and UE that experienced a bad channel quality conditions can be starved. So, the mechanism applied in PF scheduler is to weight the current data rate achievable by a UE by the average rate received by a UE. The main contribution of this study is the design of a new scheduling scheme and its performance is compared with the PF and RR downlink schedulers for LTE by utilizing the LTE Downlink System Level Simulator. The proposed new scheduling algorithm, namely the Modified-PF scheduler, divides a single sub-frame into multiple time slots and allocates the resource block (RB) to the targeted UE in all time slots for each sub-frame based on the instantaneous Channel Quality Indicator (CQI) feedback received from UEs. Besides, the proposed scheduler is also capable to reallocate RB cyclically in turn to target UE within a time slot in order to ensure the process of distributing packet data consistently. The simulation results showed that the Modified-PF scheduler provided the best performance in terms of throughput in the range of up to 90% improvement and almost 40% increment for spectral efficiency with comparable fairness as compared to PF and RR schedulers. Although PF scheduler had the best fairness index, the Modified-PF scheduler provided a better compromise between the throughput in /spectral efficiency and fairness. This showed that the newly proposed scheme improved the LTE output performances while at the same time maintained a minimal required fairness among the UEs
Ka-band return link for UAVs using adaptive spreading factor for DSSS in a DVB-RCS2 context
This paper evaluates the potential performances of a Direct Sequence Spread Spectrum (DSSS) satellite communication for Unmanned Aerial Vehicles (UAVs) in Ka-band using low directional antenna. The need to comply with the interference templates established by ITU enforces a bound to the signal power emitted toward adjacent satellites and greatly limits the accessible data rate. That prevents the UAVs communications to use a dedicated repeater for the return link. Instead, simultaneous transmission with return link communications in accordance to DVB-RCS2 standard is investigated. The proposed system is thus based on simultaneous transmission of narrow-band carriers (DVB-RCS2 primary system) and spread spectrum carriers (secondary system dedicated to UAVs). Mutual interferences are evaluated, it is shown that secondary transmissions do not affect primary systems availability, but conversely DVB-RCS2 carriers forces the secondary systems to use a high spreading factor, typically between 28 and 214 which can be updated as the number of primary active carriers changes within the beam. A compromise between secondary burst length and speed of adaptation for spreading factor is also discussed. Typically, if the targeted Packet Error Rate (PER) of the secondary link is 10e-5 and modulation is QPSK with a code rate 1/3, SNIR has to be held over 0 dB. This objective is reached with a spreading factor switching from 2e10 to 2e14 as the number of active primary carriers changes with a maximum bandwidth occupation of 90%, resulting in a data rate varying between 8 kbps and 34 kbps for the secondary system and a SNIR maintained between 1.5 dB and 4.5 dB
Final report on the evaluation of RRM/CRRM algorithms
Deliverable public del projecte EVERESTThis deliverable provides a definition and a complete evaluation of the RRM/CRRM algorithms selected in D11 and D15, and evolved and refined on an iterative process. The evaluation will be carried out by means of simulations using the simulators provided at D07, and D14.Preprin
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LTE-Advanced radio access enhancements: A survey
Long Term Evolution Advanced (LTE-Advanced) is the next step in LTE evolution and allows operators to improve network performance and service capabilities through smooth deployment of new techniques and technologies. LTE-Advanced uses some new features on top of the existing LTE standards to provide better user experience and higher throughputs. Some of the most significant features introduced in LTE-Advanced are carrier aggregation, enhancements in heterogeneous networks, coordinated multipoint transmission and reception, enhanced multiple input multiple output usage and deployment of relay nodes in the radio network. Mentioned features are mainly aimed to enhance the radio access part of the cellular networks. This survey article presents an overview of the key radio access features and functionalities of the LTE-Advanced radio access network, supported by the simulation results. We also provide a detailed review of the literature together with a very rich list of the references for each of the features. An LTE-Advanced roadmap and the latest updates and trends in LTE markets are also presented
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