外文文献原文：
Rapid MIMO-OFDM Software Defined Radio
System Prototyping
Amit Gupta, Antonio Forenza, and Robert W. Heath Jr.
Wireless Networking and Communications Group
Department of Electrical and Computer Engineering, The University of Texas at Austin
1 University Station C0803, Austin, TX 78712-0240 USA
info是什么意思Phone: +1-512-232-2014, Fax: +1-512-471-6512
{agupta, forenza, rheath}@ece.utexas.edu
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Abstract—Multiple input-multiple output (MIMO) is an attractive technology for future wireless systems. MIMO communication, enabled by the u of multiple transmit and multip
takethatle receive antennas, is known for its high spectral efficiency as
well as its robustness against fading and interference. Combining MIMO with orthogonal frequency division multiplexing (OFDM),it is possible to significantly reduce receiver complexity as OFDM greatly simplifies equalization at the receiver. MIMO-OFDM is六级 查分 currently being considered for a number of developing wireless
standards; conquently, the study of MIMO-OFDM in realistic environments is of great importance. This paper describes an approach for prototyping a MIMO-OFDM system using a flexible software defined radio (SDR) system architecture in conjunction with commercially available hardware. An emphasis on software 愚人节快乐英语怎么说permits a focus on algorithm and system design issues rather than implementation and hardware configuration. The penalty of this flexibility, however, is that the ea of u comes at the expen of overall throughput. To illustrate the benefits of the propod
architecture, applications to MIMO-OFDM system prototyping backfireand preliminary MIMO channel measurements are prented. A detailed description of the hardware is provided
along with downloadable software to reproduce the system.
I.INTRODUCTION
Multiple-input multiple-output (MIMO) wireless systems u multiple transmit and multiple receive antennas to increa capacity and provide robustness to fading [1]. To obtain the benefits in broadband channels with extensive frequency lectivity,MIMO communication links require complex space time equalizers. The complexity of MIMO systems can be reduced, however, through orthogonal frequency division multiplexing(OFDM). OFDM is an attractive digital modulation technique that permits greatly simplified equalization at the receiver. With OFDM, the modulated signal is effectively transmitted in parallel over N orthogonal frequency tones.This converts a wideband frequency lective channel into N narrowband flat fading channels. Currently OFDM is ud in many wireless digital communication systems, such as the IEEE 802.11a/g [2], [3] standards for wireless local area networks(WLANs). MIMO-OFDM technology is in the process of being standardized by the IEEE Technical Group 802.11n[
4] and promis to be a strong candidate for fourth generation(4G) wireless communication systems [5].
As the theory behind MIMO-OFDM communication continues to grow, it becomes increasingly important to develop prototypes which can evaluate the theories in real world channel conditions. During the past few years, a number of MIMO-OFDM prototypes have been developed [6]–[12].The implementations make u of FPGAs or DSPs, which require a large amount of low level programming and a fixed 乔布斯在斯坦福大学毕业典礼上的演讲point implementation. This is the preferred solution when developing high-speed implementations; however, it hinders the flexibility of the platform as the systems are not easily reconfigurable. As a result when experimenting with many different space-time coding schemes or receiver designs, a more flexible solution may be preferred.
In this paper we propo a MIMO-OFDM system architecture bad on the software defined radio (SDR) paradigm. The advantage of this approach lies in the fact that the ur is not required to have in depth hardware knowledge and may implement a number
of different schemes by simply reconfiguring the software. The platform us National Instruments radiofrequency (RF) hardware in conjunction with the LabVIEW graphical programming language. With this architecture, it is possible to define and simulate a system in a high level programming language and then amlessly apply that code towards the hardware implementation–this greatly reduces the time involved in system prototyping. Compared with [6]–[12], our prototyping platform can easily be reduplicated as it consists of commercial-off-the-shelf hardware and publicly available software. A ur who purchas the RF hardware from National Instruments and downloads the available MIMO software toolkit along with the prototyping code developed by the authors (available at [13], [14]) can realize the same rapid prototyping benefits which we discuss in this paper.
The flexibility of the current implementation of the prototype is limited by some hardware constraints, such as the bandwidth of the PCI bus, which prevents fully real-time transmission over the wireless link, and software constraints like our lack of complete synchronization algorithms in the software, which caus us to u a wired synchronizati
on channel. The spirit of this contribution is to summarize our method and describe our first efforts towards the development of a complete MIMO-OFDM platform designed for system validation and
Fig. 1. A 2 × 2 MIMO-OFDM spatial multiplexing system
剧照英文channel measurements. More work needs to be investigated to overcome the limitations and expand the capabilities of our initial design.
brentThis paper is organized as follows. Section II explores the signal model for a MIMO-OFDM system and our specific MIMO-OFDM implementation. Section III discuss the specifics of the hardware and software platform. Section IV convinceshows preliminary results fro
m our system implementation as well as channel measurements in indoor environments.
