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STLC2411

Technical perspective - Extended SCO

eSCO incorporates CRC, negotiable data rate, negotiable retransmission window and multi-slot packets.

Retransmission of lost or corrupted packets during the retransmission window guarantees on-time deliv-

ery.

Figure 4. eSCO

7.7 V1.2 detailed functionality - Adaptive Frequency Hopping

User Perspective - Adaptive Frequency Hopping

In the Bluetooth spec 1.1 the Bluetooth devices hop in the 2.4 GHz band over 79-channels. Since WLAN

802.11 has become popular, there are specification improvements in the 1.2-SIG spec for Bluetooth

where the Bluetooth units can avoid the jammed bands and thereby provide an improved co-existence

with WLAN.

Technical perspective - Adaptive Frequency Hopping

Figure 5. AFH

First the Master and/or the Slaves identify the jammed channels. The Master decides on the channel dis-

tribution and informs the involved slaves. The Master and the Slaves, at a predefined instant, switch to the

new channel distribution scheme.

No longer jammed channels are re-inserted into the channel distribution scheme. AFH uses the same hop

frequency for transmission as for reception.

SCO

SCO

SCO

SCO

ACL

ACL

SCO

SCO

eSCO retransmission window

t

t

WLAN used frequency

WLAN used frequency

t

f

f

AFH(79)

AFH(19<N<79)