What is the default Guard Interval in 20 and 40MHz on an Aruba Controller?
Product and Software: This article applies to ArubaOS Version 220.127.116.11.
- For digital signals, data is modulated onto the carrier signal in bits or collection of bits called symbols. The guard interval is a period of time between symbols that accommodate for the late arrival of symbols due to multipath reception which will cause intersymbol interference (ISI), and data corruption.
- 802.11a/g radios use an 800 nanosecond guard interval (GI) between OFDM symbols
- 802.11n does not only support an 800 nanosecond guard interval, but also support a shorter 400 nanosecond guard interval.
- A shorter guard interval results in a shorter symbol time, which increases the data rates by about 10% and increase throughput greatly.
- Short guard interval should be used in only good RF environment, otherwise intersymbol interference because of shorter GI will result in data corruption, layer 2 retransmission and throughput will be adversely affected.
NOTE: By default, short guard interval in 20 MHz and 40Mhz mode is enabled in Aruba HT-SSID profile.