1424 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, VOL. 8, NO. 3, MARCH 2009 Field Measurements and Performance Analysis of an 802.16 System in a Suburban Environment Jeffrey De Bruyne, Wout Joseph, Member, IEEE, Leen Verloock, Christof Olivier, Wim De Ketelaere, Member, IEEE, and Luc Martens, Member, IEEE Abstract—This paper investigates the actual measured perfor- mance of an 802.16-based system. A measurement methodology for evaluating the performance is proposed, which is then used for studying and comparing the results of different scenarios. More specifically, the influences of changing the modem height from 2.5 m to 6 m and base station height from 15 m to 45 m are analyzed and discussed in this paper, and it will be shown that only the latter one has a significant effect on the coverage and the performance. Furthermore, the relationship between the carrier- to-interference-noise ratio (CINR) and the wireless link through- put is analyzed, and a semi-empirical model will be proposed. The model remains identical for the different scenarios, emphasizing the usefulness of the obtained model. Indoor reception is also analyzed, and it will be shown that the reception at locations close to the window is approximately 7 dB higher than deeper inside the building. A profound statistical analysis is then performed to validate both the performance measurements and the model, and excellent correspondence is obtained. Finally, as the system supports link adaptive modulation and coding, the results of its effectiveness are discussed in this paper. Index Terms—IEEE 802.16, performance, field measurements, broadband wireless access, WiMAX. I. I NTRODUCTION T HE last decade there has been an increasing demand for broadband network access. Most of these broadband services have been delivered by cable and Digital Subscriber Line (DSL) operators, who provide high-speed services to their clients. Because of the increasing demand for high- speed services, there is a great interest in alternative wire- less low-cost solutions to provide broadband network access, especially in those areas where a wired infrastructure still has to be expanded. This paper focuses on Worldwide In- teroperability for Microwave Access (WiMAX), a wireless broadband technology based on the IEEE 802.16-2004 [1] and ETSI TS102177 [2] standards, which promise high data rates over large distances. A 3.5 GHz 802.16-2004 system (Fixed WiMAX) for non- Line-Of-Sight (nLOS) operation is analyzed as these systems are already being deployed at this time. The competitiveness of WiMAX will largely depend upon the actual ranges and data rates that can be achieved. A lot of research to estimate Manuscript received January 21, 2008; revised May 19, 2008 and July 29, 2008; accepted September 5, 2008. The associate editor coordinating the review of this paper and approving it for publication was D. Huang. J. De Bruyne, W. Joseph, L. Verloock, and L. Martens are with the Dept. of Information Technology, Ghent University/IBBT, Gaston Crommenlaan 8 box 201, B-9050 Ghent, Belgium (e-mail: Wout.Joseph@intec.ugent.be). C. Olivier and W. De Ketelaere are with Excentis, Gildestraat 8, B-9000 Ghent, Belgium (e-mail: wim.deketelaere@excentis.com). Digital Object Identifier 10.1109/TWC.2009.080085 the coverage and throughput of the WiMAX technology has already been performed. However, until now, almost only theoretical analyses and simulations of the performance of 802.16-based systems have been done investigated [3]–[11]. In [9] and [10] propagation models for WiMAX are proposed, which can be used to estimate coverage and throughput. In [9], a theoretical performance analysis for an 802.16 system is presented, while in [10], measurements of the CINR are shown, but actual throughput, latency, and jitter have not been determined. In [11], limited measurements of throughput for one specific modulation scheme are presented. Thus, only few data of WiMAX performance measurements is available in literature. It is clear that measurements of the actual performance of a real WiMAX system are necessary, which stresses the importance of this paper. This paper analyzes the experimental results of the downlink (DL) performance of the Fixed WiMAX system for different scenarios in a suburban environment in Ghent (Belgium). The influence of different base station (BS) and modem heights, and the difference between outdoor and indoor reception are discussed. Firstly, the measurement methodology and the con- figuration of the WiMAX system are described in Section II. Also, the measurement equipment and the parameters of the setup for the different investigated scenarios are discussed. Secondly, short-term measurements are executed at different locations for the different scenarios. The results of these short-term measurements are presented in Section III. The relationship between CINR and link performance (expressed in throughput) for the different outdoor scenarios is analyzed, resulting in a model that will be generally applicable for dif- ferent scenarios. Furthermore, indoor measurements are per- formed, and more specifically, the difference in performance at locations near the window, and deeper inside the building is investigated. Thirdly, the short-term measurements and model are validated by a statistical analysis in Section IV. Finally, the effectiveness of the link adaptive modulation is investigated in Section V. For this purpose, the modulation scheme selected by the WiMAX system is analyzed for different conditions and compared with the experimentally determined CINR. The proposed model and the measurement results can be used by WiMAX network providers for their fixed WiMAX deployment, to ensure that their networks deliver the required wireless link quality (i.e., the required minimum throughput) for each enabled service. Note that the conclusions drawn from our measurements mainly reflect the particular equipment under test. 1536-1276/09$25.00 c  2009 IEEE