Page 510 - From GMS to LTE

496 From GSM to LTE-Advanced Pro and 5G

Frame 176: 19 bytes on wire (152 bits), 19 bytes captured (152 bits)
Encapsulation type: Bluetooth H4 with linux header (99)
[...]
[Protocols in frame: hci_h4:bthci_acl:btl2cap:bthid ]
Point-to-Point Direction: Received (1)
Bluetooth HCI H4
[Direction: Rcvd (0x01)]
HCI Packet Type: ACL Data (0x02)
Bluetooth HCI ACL Packet
.... 0000 0010 0011 = Connection Handle: 0x0023
..10 .... .... .... = PB Flag: First Automatically Flushable Packet
(2)
00.. .... .... .... = BC Flag: Point-To-Point (0)
Data Total Length: 14
Bluetooth L2CAP Protocol
Length: 10
CID: Dynamically Allocated Channel (0x0041)
[PSM: HID-Interrupt (0x0013)]
Bluetooth HID Profile
1010 .... = Transaction Type: DATA (0x0a)
.... 00.. = Parameter reserved: 0x00
.... ..01 = Report Type: Input (0x01)
Protocol Code: Keyboard (0x01)
0... .... = Modifier: RIGHT GUI: False
.0.. .... = Modifier: RIGHT ALT: False
..0. .... = Modifier: RIGHT SHIFT: False
[...]
Reserved: 0x00
Keycode 1: a (0x04)
Keycode 2: <ACTION KEY UP> (0x00)
[...]
0000 02 23 20 0e 00 0a 00 41 00 a1 01 00 00 04 00 00
0010 00 00 00

Figure 7.27 HID input message sent from a keyboard.

remote‐controlled switches and lights. One radio technology to connect such devices is
Wibree, which was introduced in 2006 by Nokia and subsequently integrated into the
Bluetooth standard in version 4.0 [24]. It is referred to as Bluetooth Low Energy.
In contrast to ‘classic’ Bluetooth, the idea of Bluetooth Low Energy, also referred to as
‘Bluetooth Smart’ and ‘BLE’, is to transmit only a small amount of data (e.g. a tempera-
ture value) and to do this in a very power‐efficient manner. Rather than being a data
stream, BLE could better be described as a system for reading and writing to variables
on a remote device and pro‐actively informing the device about changes in a variable
from the remote side. Another application of BLE is to broadcast information periodi-
cally without any further interaction with another device (connectionless broadcast-
ing). This functionality is used, for example, for beacons that enable applications on
devices such as smartphones to detect that the user is in a certain area. Beacons can also
be used to improve indoor positioning accuracy via triangulation and analysis of the
signal strength of broadcasts received from different beacons. It is important to note
that the Bluetooth Low Energy radio, the lower layers of the protocol stack and its
behavior differ significantly from ‘classic’ Bluetooth even though some terminology is
shared between the two technologies.