ASCOM I62 Troubleshoot Manual

TD 92685EN
28 June 2012 / Ver. A
Troubleshooting Guide
Ascom i62 VoWiFi Handset
17
3. The VoWiFi Handset as
4 The end of an unscheduled service period is when all of the buffered data has been
released and there are no more frames to transmit. The event is indicated by the
transmission of a QoS Null data frame.
Figure 3. Handset Operating in U-APSD PS Mode
AP
t=0
t=20 ms
3. The AP receives the uplink
packet and immediately transmits
the buffered packet.
The sequence is repeated each
20 ms
HS
1. The AP buffers a packet
destined for the handset
2. The handset transmits
a speech packet with
EDCA “Voice”
An example of an U-APSD flow is described in detail in section 7.2.3 Packet Classification of
U-APSD in the AP on page 56.
3.5.3 Recommended Values
A low DTIM value will cause the handset to wake up and check for incoming data more
frequently. A normal valu
e is a beacon Interval of 100 TUs and a DTIM of 5, which causes a
wake up approximately 2 times per second.
Note: The DTIM value should norm
ally be set to 5. Values lower than 5 reduce the handset
sleep period and shorten the battery life.
For additional information, always check the Applic
ation Partner Program, Ascom Inter-
Operability Reports for specific recommendations applicable to the particular vendor
equipment.
3.5.4 Screen Saver
The handset LCD display also consumes a lot of power. Unne
cessary use or b
rowsing of the
handset display can therefore consume battery power quickly. A Screen saver parameter
setting exists in the handset configuration, which may be set to “black” in the PDM as an
additional power saving measure.
3.6 Roaming
One of the most important design criteria for good functionality in a voice system is to
deploy sufficient APs to create adequate RF coverage throughout a site. In addition, the
coverage areas provided by the individual APs must be deployed in such a way as to allow a
user to roam throughout the site without any deterioration in the quality of an ongoing call.
The user must also remain connected to the network at all times even when the handset is
in idle mode. Failure to adequately support roaming may result in audible clicks and other
disturbances in a voice call.
Roaming can be described as disconnecting from
the current AP as the
user moves away
from it and the signal attenuates. The user then connects to a new AP that offers an

ASCOM I62 Specifications

General

Display	2.4 inch QVGA
Connectivity	Wi-Fi, Bluetooth
Battery	Li-ion
Technology	GSM
Key features	Bluetooth, Wi-Fi