The term Guard Interval (GI) is used in WLANs according to 802.11.
Guard Interval (GI) is a short period between the transmitted data packets. The guard interval is used as a safety interval to ignore faulty data packets. The longer the GI time, the better the freedom from errors and the multipath capability. However, a longer guard interval reduces the data rate, which is reflected in the Modulation and Coding Scheme( MCS) values. For 802.11ac, the guard intervals are 800 ns and 400 ns.