Study of Guard Interval Duration on the Operation Impact of IEEE 802.11 Network

Abstract

Purpose. One of the new additions in the IEEE 802.11n standard amendment was the introduction of the short inter-symbol guard interval, which makes it possible to operate at slightly higher data rates. However, using a short guard interval is not always recommended. The fact is that on some types of sites where radio coverage is provided, the peculiarities of signal propagation with a short guard interval may give worse frame retry rate. In modern networks, this aspect remains more relevant than ever, and the task of correct guard interval configuration remains relevant for both the designer and the administrator of a wireless network. In order to conduct a comparative analysis of the measurement results with a short and long guard inter-symbol interval, it is necessary to conduct a full-scale radio site-survey of industrial WLAN site. As part of the present experiment, a WLAN was investigated at a site in one of the industrial zones of St. Petersburg. The main goal of the work is to experimentally determine the benefits that can be obtained from choosing a modulation and coding scheme with a long inter-symbol guard interval using the example of a distributed wireless network of the IEEE 802.11n/ac/ax standard. A related goal is to experimentally test the potential for reducing the radiation power of access points radios in order to improve network performance. Methods. Conducting a radio survey of a wireless network at a typical industrial site with subsequent analysis of its results. Novelty. The novelty of the presented solution includes a full-scale examination of an actually operated industrial network with simultaneous monitoring of characteristics at various levels of the OSI model: physical (spectrum analysis), channel (protocol analysis), application (control of application operation). Results. Analysis of the collected data shows a practically significant difference between the values of the frame retry rate for different values of the duration of the inter-symbol guard interval and the radiation power of the radio modules of the access points. Practical relevance. In is quantitatively shown that there is a reduction in frame retry rate by 8-10% in an production wireless network, achievable through correct control of the inter-symbol interval length for an industrial site.