TD 92408EN
9 December 2011 / Ver. G
System Planning
Ascom VoWiFi System
1
1 Introduction
This document is intended as a guide for considerations on WLAN infrastructure planning
and installation to obtain maximum performance with respect to voice quality. The
document handles the RF aspects in the 2.4 GHz and 5 GHz band of a multi-cell WLAN
system with a focus on Access Point (AP) placement.
In addition to theoretical discussions o
f
the RF environment in a WLAN system, this
document also provides practical examples of how to place APs and verify the placement
with the built-in site survey tools included in the VoWiFi Handset.
How to Use this Document
We recommend the use of the WLAN infrastructure m
a
nufacturer's installation guide for
system planning, logical connection, and configuration of the WLAN system and APs. This
document is intended for use alongside the WLAN manufacturer’s documentation in order
to maximize the voice quality in the Ascom VoWiFi system.
1.1 Abbreviations and Glossary
Figure 1.
802.11a IEEE 802.11 standard for transmission rate of up to 54Mbps, operates
in the 5GHz spectrum.
802.11b IEEE 802.11 standard for transmission rate of up to 11Mbps, operates
in
the 2.4GHz spectrum.
802.11g IEEE 802.11 standard for transmission rate of up to 54Mbps, operates
in
the 2.4GHz spectrum.
802.11d IEEE 802.11 standard for regulatory domains.
802.11e IEEE 802.11 standard that defines Quality of Service (QoS) for
W
LAN.
802.11i IEEE standard security protocol for 802.11 wireless networks that was
developed to replace the ori
ginal WEP protocol.
802.11n IEEE 802.11 standard for transmission rate of up
to 600 Mbps,
operates in the 2.4GHz and 5GHz spectrum.
AES Advanced Encryption Standard.
AP Access Point:
a radio transceiver providing LAN connection to wirel
e
ss devices.
BSS Basic Service Set
CAC Call Admission Control
CCA Clear Channel Assessment
CCMP Counter Mode with Cipher Block Cha
i
ning Message Authentication
Code (CBC-MAC) Protocol
CCKM Cisco Centralized Key Management
Channel
b
ond
ing
A mode of operation in which two channels are combined to increase
performance in some environments.
Delay spread Measure of the multipath richness of a chann
el. Because of multipath
reflections, the channel impulse response of a wireless channel looks
like a series of pulses.
Device Manager An application that handles devices such as handsets and chargers. It
exists in two variants; one server based (delivered in an Ascom Elise
pr
oduct like IMS3, UniteCM) and one stand-alone Windows application
(PDM).
