8/9/2006 2:45-3:30pm

8/9/2006 2:45-3:30pm Integrating WiFi Telephony Into the Enterprise Communications Infrastructure Organizations are become increasingly aware of the benefits VoIP provides as a collaborative communication tool. Those businesses that demand communicative flexibility and efficiency are now beginning to examine new wireless technologies to help meet these needs. The introduction of new wireless VoIP solutions can now offer the type of vital integration and convergence of multiple communication tools that today’s mobile business must have to be successful. This session will cover the development of wireless VoIP solutions, as well as the issues you need to consider before implementing a wireless communication solution: including network assessment, varying approaches to wireless design, securing your wireless network and the potential return on a wireless investment.This will be a shared session with Spectralink. NEC will speak first from 2:45-3:05 and Spectralink will follow from 3:05-3:25, with a 5 minute Q&A at the end.

Tom GradyProduct ManagerNEC Unified Solutions

Integrating WiFi Telephony Into the Enterprise Communications Infrastructure

www.voipdeveloper.comAugust 8-10, 2006

Santa Clara, CaliforniaHyatt Regency Santa Clara

Voice User Requirements

• Coverage and Bandwidth specific to voice traffic– Site survey for voice different than for data (higher BW requires higher

signal strength)– IP assessment on wired network for VoIP support may be needed

• Security– Network security more intrusive to voice latency and jitter concerns

• Encryption and authentication add CPU latency to voice stream

• Quality of Service– Delay and jitter negatively impact voice as opposed to data– Must give priority to voice traffic over data– Admission control important in dense user environment

• Mobility

• Voice traffic on wireless network introduce new layers of service requirements above data traffic requirements



Network requirements for voice

• Must Consider– Latency- the time it takes to get information through a network– Jitter- if a network provides various latency for different

packets, it introduces jitter– Packet Loss- packets lost due to collisions or retransmissions– AP Handoff- the time it takes a device to re-associate and re-

authenticate at Layer 2

• Wireless Network Requirements for Voice– Maximum jitter < 5 msec– Maximum latency < 50 msec– Maximum Packet Loss < 1%– AP handoff < 50 msec



Wireless Voice Considerations

• No time for retransmission of lost or corrupted packets– Real-time, full duplex voice conversations require voice packets

to received within tens of milliseconds

• Users are extremely very mobile– Frequent handoffs– Real-time application

• Coverage issues are audible– Poor voice quality creates the perception of substandard

product

• Cover all user-accessible areas– Stairwells, bathrooms, break rooms and lobby areas must have

coverage



Remember…



• Signal Strength – “smaller” number is better (stronger signal)

– Data WLAN: -85dBm– Voice WLAN: -65 to -70dBm with 15% - 25% cell overlap

• Signal-to Noise Ratio – higher is better

– Data WLAN: 15dB– Voice WLAN: 20dB minimum for good quality voice calls

• Interference– Eliminate overlapping channel interference with proper channel

assignments

• Data Rate – depends on radio type – a/b/g

– Will be affected by network load

Voice has Different Requirements



Power and Range

2 Mbps DSSS250-350 feet radius@100mW

5.5 Mbps DSSS130-150 feet radius@ 100mW

11 Mbps DSSS100-150 feet radius@ 100mW

Voice Traffic



Design Approaches

• Consider:– Number of potential concurrent clients– Voice clients

• Available vs. concurrent

– Consider second or third overlappingaccess point

– Consider output power constraints• Reduce cell size, hence number of concurrent clients



Why do a Wireless Site Survey?

• To accurately determine:– The number and placement of access points (AP’s)

needed for required coverage and throughput.– Where “blind spots” are, so you can avoid them.– Are there any unauthorized AP’s (rogues) already

connected to your network?– Is there any RF interference present?



The Final Solution

220 feet



To recap…

• A wireless site survey accurately determines:– The number of access points (AP’s) needed for adequate

coverage.– The placement of access points (AP’s) for coverage and

throughput.– Where “blind spots” are, so you can avoid them.– Are there any “rogues” already connected to the network?– Is there any RF interference present?– Are there other 802.11 networks in the vicinity?



QoS Considerations for High Quality Voice

• Admission Control is required– Streaming applications need priority service– Bandwidth management required to maximize capacity

and minimize contention

• Battery life must be maximized– Traffic is predictable– Schedule periods of “sleep” are possible

• VoIP Bandwidth Control• Dynamic QoS• Fast Handoff



VoWLAN: Mobility & Fast Roaming

• Wireless voice users must be free to roam• Fast roaming requires sub 150ms handoffs; ideally

<50ms• No dropped calls due to roaming across layer 2 AP• No dropped calls due to subnet roaming• Must be able to support security options within fast

roaming constraints



Security Considerations for Voice

• Security threats– Intercepting telephone calls is expensive relative to the value of the

information– Access to corporate network is the primary issue

• Usability– No established paradigm for “logging in” to a telephone

• Minimize handoff duration– Clients are highly mobile– Packets have a limited useful life – Streaming application have low delay tolerance

• Application specific devices– Handsets do not necessarily use standard PC operating systems– Handheld devices may have limited processing power, memory

constraints, and battery life issues



Security Components

• Information access protection– Encryption algorithm “scrambles” data into unintelligible information

using a “key”– Data is unencrypted using the same key at the receiving end

• Key management– Process for providing keys at each end of the secured link– Provides mechanism for changing keys at appropriate intervals

• Authentication– Mechanism to verify identity of users– Prevents “man in the middle” attack

• Message integrity– Verifies that the information current– Prevents replay or “cut and paste” attacks



Wi-Fi Protected Access (WPA)

• Defined by the Wi-Fi Alliance– Mandatory for Wi-Fi certification

• Based on IEEE 802.11i– Intended to be software/firmware upgrade from WEP for legacy

wireless devices• Key elements

– 802.1x authentication• Extensible Authentication Protocol – Transport Layer Security (EAP-

TLS) for authentication management systems• Pre-Shared Key (PSK) for real-time applications

– Encryption and key rotation• Temporal Key Integrity Protocol (TKIP)• RC-4 encryption algorithm

– Validation• “Michael” message integrity check (MIC)



Security Ramifications for Voice

• Handoff authentication delay must be addressed for enterprise applications– Pre-shared key (WPA/WPAII)

• Usability issues– Simple user login process

• Device design– Additional processing power and memory requirements



Value Proposition

• To build a solution platform that enables converged mobility to penetrate multiple verticals and unifies voice, multimedia and data in the wireless workspace while enabling robust mission-critical business applications and solutions



Converged Mobility – ROI in HealthCare

Source: Office of Medicare and Medicaid Financing

2003 2006

8/9/2006 2:45-3:30pm

Documents

voice latency

voice packets

voice different

wireless voice considerations

network load voice

wireless network requirements

voice maximum jitter

range voice traffic