54
QUALITY OF SERVICE FOR WIRELESS TECHNOLOGY IN THE
WIDEXLINK SYSTEM
WidexLink wireless technology enables communication between two
partners of a binaural pair of DREAM hearing aids and with their matched
external devices . The requirements for the quality of service (QoS) vary
among the various components and their intended user scenarios .
For programming, these requirements include a BER (Bit Error Rate) bet-
ter than 10
-3
, at a bitrate of 212 kbits/s, a semi-duplex transmission with a
required acknowledge, a transmission latency in each direction (2x) and
a receive-to-transmit mode (RX to TX) time . The data are saved in the
hearing aid even when transmission is interrupted .
During daily use, the requirements on audio streaming between hearing
aids include a BER better than 10
-3
. The communication is simplex with a
bitrate of 212 kbits/s . The additional audio decoding in this mode results
in a longer latency which is less than 10 ms . For remote control com-
mands the QoS requirements include a BER better than 10
-2
. The lower
BER requirement results from redundant transmissions . Each key press
results in transmissions of 7 data packages of which only one is needed
for a successful communication .
