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L2CAP

Logical Link Control and Adaption Layer Protocol. Used within the Bluetooth protocol stack, it provides a data link layer for Bluetooth; passes packets to either the HCL (Host Controller Interface) or, on a hostless system, directly to the Link Manager/ACL link.

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Latency

The delay in communication between the sending and receiving of a signal. Latency is an inherent feature of electronic communications, and can be thought of as the sum of all factors (in serializing, queuing, and processing of the transmission) which cause the delayed receipt of a transmitted message. These factors include interference, crosstalk, attempts at re-sending, and more. Through proper configuration of radio hardware, latency can be reduced to a minimum for the best device performance.

 


 

LED (SCU Global Setting)

LED is an SCU Global setting that indicates whether or not an LED is used. This setting applies only to select Summit devices/radios.

 


 

Limited Channel Set

In the 2.4 GHz frequency band used for 802.11b and 802.11g, there are between 11 and 14 available channels (depending upon regulatory domain). Of these channels, only 3 or 4 (depending upon regulatory domain) do not overlap with each other and are available for wireless LAN operation. When operating in the FCC regulatory domain (North and South America, parts of Asia, and the Middle East) most wireless LAN infrastructures are configured to operate on channels 1, 6, and 11. In the ETSI regulatory domain (Europe, Africa, and parts of Asia and the Middle East) most wireless LAN infrastructures are configured to operate on either channels 1, 6, and 11 or 1, 7, and 13.

By default, Summit's software is configured to scan all 2.4 GHz channels prior to initiating a roam. During a scan, a client device is unable to send or receive data; this means that the longer a scan period, the lower the client's performance.

Limiting the set of channels to be scanned (prior to a roam) to only the channels that are in use in the WLAN infrastructure is an effective means of decreasing scan time and improving performance. A Limited Channel Set may be enabled in two ways:

  • In Summit software versions 1.3 and later, the two most common limited channel sets (1, 6, 11 and 1, 7, 13) may be enabled through the "BG Channel Set" menu item on the Global Settings tab in the Summit Client Utility (SCU).
  • For earlier versions of Summit software (or if you want to limit a channel set to channels other than those found on the SCU Global Settings tab), you can manually edit the registry using the following process:
  • Find the "bLRS" registry entry (a bitmask with bit 0 corresponding to channel 1, bit 1 to channel 2, etc.).
  • If a bit is set, that channel will be scanned prior to a roam and associations will be allowed on that channel. If the bit is not set, that channel will not be scanned and associations on that channel will not be allowed. By default the bitmask, in hex, is set to: 
    • HEX: F F F F
    • The binary equivalent of which is: 1111 1111 1111 1111
    • This means that all channels will be scanned and will allow for associations. To limit the channel set, manually edit the bitmask to selectively enable and disable channels. For example, to manually set the channel set to enable channels 11, 6, and 1 (and disable all others), use the following entry:
      • HEX: 0 4 2 1
      • The binary equivalent of which is: 0000 0100 0010 0001

 


 

Limited Modular Approval

A Limited Modular Approval (LMA) may be granted if the device does not meet all modular requirements and if compliance can be demonstrated under the operating conditions in which the device will be used. An LMA is only issued in circumstances where the Grantee can demonstrate that it will retain control over the final installation of the device (to ensure compliance of the end product).

Note: FCC and IC approvals do not allow the use of LMAs with collocated radios nor with portable devices.

 


Link Management Protocol (LMP)

In a Bluetooth device, the logic layer that manages the connection between the host device and remote device(s) is called the Link Manager. Link Management Protocol is the standard for these communications. LMP messages are transmitted over an Asychronous Connection-Oriented Link (ACL) logical transport. This layer is distinct from the ACL layer that exchanges user data.


 

Logon Options (SCU Global Setting)

On Windows XP, SCU supports two sets of logon options:

  • Single Signon (SSO) - When selected, SCU uses the Windows username and password as the credentials for 802.1X (EAP) authentication.
  • Pre-Logon Connection - When selected, SCU uses specified and saved parameters and credentials to achieve 802.1X (EAP) authentication before Windows login.

To use logon options, follow these steps:

  1. Select Logon Options in the Property area on the Global window.
  2. Click Logon Options.
  3. Complete the dialog box or boxes that appear.

Single Sign On (SSO)

To activate SSO on the PreLogon dialog box, follow these steps:

  1. Check the Use Windows login username and password when available box.
  2. Click OK.

When the active profile is configured to use LEAP, PEAP-MSCHAPv2, PEAP-GTC, or EAP-FAST, then for EAP authentication Summit software ignores the username and password saved as credentials in the profile and instead uses the username and password entered for the Windows logon.

Pre-Logon Connection

Pre-logon connection is intended for situations where all of the following are true:

  • EAP authentication is required for a WLAN connection.
  • SSO is configured, so the Windows username and password are used as the credentials for EAP authentication.
  • It is desirable to establish a WLAN connection before the user completes the Windows login.

In other words, pre-logon connection enables EAP authentication to complete successfully before the user has completed the Windows login to satisfy SSO.

To activate pre-logon connection on the PreLogon dialog box, follow these steps:

  1. Check the Enable pre-logon connection box.
  2. Specify the authentication delay and association timeout.
  3. Click Credentials to specify credentials on another dialog box.
  4. Click OK.

The pre-logon connection method varies by EAP type. For LEAP, PEAP, or EAP-FAST, if the active profile includes credentials, then Summit software uses those credentials; otherwise, Summit software must obtain the credentials from the Windows login or by prompting the user. If SSO is enabled, then Summit software uses the last valid Windows login credentials. If SSO is not enabled, then pre-logon authentication will fail, because Summit software cannot prompt the user; a WLAN connection will not be established until Windows login succeeds and the user can be prompted.

For PEAP, you can specify on the PreLogon Credentials dialog box the CA certificate to be used for pre-logon server validation. This certificate can differ from that used for post-logon server validation.

For EAP-TLS, you must specify on the PreLogon Credentials dialog box the user certificate to be used for pre-logon authentication.

If both SSO and pre-logon connection are active and EAP authentication is performed before Windows login, then after Windows login Summit software performs EAP authentication again using the credentials specified on Windows login.

 


Low Energy Link Layer (LE LL)

In a Bluetooth Low Energy connection, the Link Manager Protocol (LMP) is replaced with the Low Energy Link Layer (LE LL). This performs similar tasks to the LMP but is simpler, and oversees all aspects of connection and security. This layer is organized close to the hardware, allowing for effective low-energy link management.


 

LTK

Microsoft Logo Test Kit. Provides a set of tests for specific Windows Mobile-based devices

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