3 high data rate frame buffer access – Rainbow Electronics AT86RF231 User Manual
Page 138
138
8111A–AVR–05/08
AT86RF231
Figure 11-6. High Data Rate Frame Structure
Due to the overhead caused by the SHR, PHR as well as the FCS the effective data rate is
smaller than the selected data rate. That depends further on the length of the PSDU. A graphical
representation of the effective data rate is shown in
Figure 11-7. Effective Data Rate "B" for High Data Rate Mode
Consequently, High Data Rate transmission and reception is useful for large PSDU lengths due
to the higher effective data rate, or to reduce the power consumption of the system. Further,
using High Data Rate Modes the active on-air time is significantly reduced.
11.3.3
High Data Rate Frame Buffer Access
The Frame Buffer access to read or write frames for High Data Rate transmission is similar to
the procedure described in
Section 6.2.2 “Frame Buffer Access Mode” on page 20
. However,
during Frame Buffer read access the last byte transferred after the PSDU data is the ED value
rather than the LQI value.
250 kb/s
0
time [µs]
192
SF
D
PHR
832
1472
2752
500 kb/s
SF
D
PHR
1000 kb/s
SFD
PH
R
2000 kb/s
SF
D
PHR
512
FCS
FCS
PSDU: 80 octets
PSDU: 80 octets
PSDU: 80 octets
PSDU: 80 octets
0
200
400
600
800
1000
1200
1400
1600
0
20
40
60
80
100
120
PSDU length in octets
B [kb/s
]
2000
1000
500
250
2000 kb/s
1000 kb/s
500 kb/s
250 kb/s