D-Link DWL-X8630AP Product Manual - Page 28

Unified Access Point Administrator's Guide Section 4 - Managing the Access Point Field Description Channel Bandwidth (802.11n, 802.11ac and 802.11ax modes only) The 802.11n specification allows a 40 MHz wide channel in addition to the legacy 20 MHz channel available with other modes. The 40 MHz channel enables higher data rates but leaves fewer channels available for use by other 2.4 GHz and 5 GHz devices. The 802.11ac/ax specification allows an 80 MHz-wide channel in addition to the 20 MHz and 40 MHz channels. Set the field to 20 MHz to restrict the use of the channel bandwidth to a 20 MHz channel. For the 802.11ac/ax mode, set the field to 40 MHz to prevent the radio from using the 80 MHz channel bandwidth. Primary Channel (802.11n modes only) This setting can be changed only when the channel bandwidth is set to 40 MHz. A 40 MHz channel can be considered to consist of two 20 MHz channels that are contiguous in the frequency domain. These two 20 MHz channels are often referred to as the Primary and Secondary channels. The Primary Channel is used for 802.11n clients that support only a 20 MHz channel bandwidth and for legacy clients. Select one of the following options: •) Lower - Set the Primary Channel as the lower 20 MHz channel in the 40 MHz band. •) Upper - Set the Primary Channel as the upper 20 MHz channel in the 40 MHz band. Short Guard Interval This field is available only if the selected radio mode includes 802.11n. Supported The guard interval is the dead time, in nanoseconds, between OFDM symbols. The guard interval prevents Inter-Symbol and Inter-Carrier Interference (ISI, ICI). The 802.11n mode allows for a reduction in this guard interval from the a and g definition of 800 nanoseconds to 400 nanoseconds. Reducing the guard interval can yield a 10% improvement in data throughput. Select one of the following options: •) Yes - The AP transmits data using a 400ns guard Interval when communicating with clients that also support the short guard interval. •) No - The AP transmits data using an 800ns guard interval. Protection The protection feature contains rules to guarantee that 802.11n transmissions do not cause interference with legacy stations or APs. By default, these protection mechanisms are enabled (Auto). With protection enabled, protection mechanisms will be invoked if legacy devices are within range of the AP. This causes more overhead on every transmission, which will impact performance. However, there is no impact on performance if there are no legacy devices within range of the AP. You can disable (Off) these protection mechanisms; however, when 802.11n protection is off, legacy clients or APs within range can be affected by 802.11n transmissions. The 802.11 protection feature is also available when the mode is 802.11b/g. When protection is enabled in this mode, it protects 802.11b clients and APs from 802.11g transmissions. Note: This setting does not affect the ability of the client to associate with the AP. Beacon Interval Beacon frames are transmitted by an AP at regular intervals to announce the existence of the wireless network. The default behaviour is to send a beacon frame once every 100 milliseconds (or 10 per second). Enter a value from 20 to 2000 milliseconds. DTIM Period Specify a DTIM period from 1 to 255 beacons. The Delivery Traffic Information Map (DTIM) message is an element included in some Beacon frames. It indicates which client stations, currently sleeping in low-power mode, have data buffered on the AP awaiting pick-up. The DTIM period you specify indicates how often the clients served by this AP should check for buffered data still on the AP awaiting pickup. The measurement is in beacons. For example, if you set this field to 1, clients will check for buffered data on the AP at every beacon. If you set this field to 10, clients will check on every 10th beacon. RTS Threshold Specify a Request to Send (RTS) Threshold value between 0 and 2347. The RTS threshold indicates the number of octets in an MPDU, below which an RTS/CTS handshake is not performed. Changing the RTS threshold can help control traffic flow through the AP, especially one with a lot of clients. If you specify a low threshold value, RTS packets will be sent more frequently. This will consume more bandwidth and reduce the throughput of the packet. On the other hand, sending more RTS packets can help the network recover from interference or collisions which might occur on a busy network, or on a network experiencing electromagnetic interference. 2021 Unified Access Point Administrator's Guide Page 28