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17
Denitions
Term Denition
Symbol Rate The rate at which analogue symbols are transmitted at the physical layer.
Protocol Data Rate The transmission rate of bits relating to Bluetooth protocol data units (PDUs) including
their application data payload but excluding FEC data which is included in packets
when the LE Coded PHY is in use.
Approximate Max.
Application Data Rate
An approximate maximum rate at which application data can be communicated
between applications on connected devices. Application data is transported in the
payload part of various PDUs with the remainder of the protocol data rate being
consumed by Bluetooth protocol data.
CRC Cyclic Redundancy Check. A eld used in the detection of transmission errors. This
eld and its use is dened in the Link Layer.
6.4 Time-Division
A Bluetooth LE radio is a half-duplex device, capable of transmitting and/or receiving but not both
at the same time. However all PHYs are used in a Time Division Duplex (TDD) scheme so that the
appearance of a full-duplex radio is given.
6.5 Transmission Power and Receiver Sensitivity
The Physical Layer denes transmitter characteristics including output power requirements for which
the specication states that:
ࣹ the output power level at the maximum power setting shall be between 0.01 mW (-20 dBm) and 1
00 mW (+20 dBm).
Regulatory bodies in dierent parts of the world may override these requirements and implementers
must ensure that devices are compliant with applicable local regulations.
Receiver sensitivity is dened as the receiver input level for which a particular Bit Error Rate (BER)
is experienced. The BER specied varies according to the length of a received packet because the
Link Layer appends a single Cyclic Redundancy Check (CRC) eld to each packet and uses this as
a mechanism for detecting one or more bits in error in the decoded packet. Since packets vary in
length, and there is one CRC per packet, the length of the packet aects the calculated BER.
Typically quoted in discussions about Bluetooth LE receiver sensitivity is the BER of 0.1% which is the
maximum error rate for packets up to 37 octets in length.
Other receiver characteristics dened by the Physical Layer include interference performance,
out-of-band blocking, intermodulation characteristics, maximum usable input level and the required
accuracy of received signal strength indications (RSSI) if supported.
6.6 Antenna Switching
Bluetooth LE supports two methods of calculating the direction from which a received signal was
transmitted. The rst is called Angle of Arrival (AoA) and the second, Angle of Departure (AoD). Both
methods involve one device having an array of antennae and a process of switching from one antenna
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