Quality of service means many different things,
but in the end its all about what the subscriber likes.

Quality of service (Qos) is one of those elusive goals for wireless carriers and other service providers. Everyone wants it but it can be difficult to define, and tougher to achieve. Still, it’s at the top of everyone’s list of key performance indicators.

J.D. Power and Associates, in its periodic ratings of overall wireless carrier performance, says call performance and reliability is the No. 1 factor consumers have in assessing their carrier. Performance and reliability is nearly twice as important to consumers as the No. 2 factor, brand image, and is more than double the third factor, cost.

In fact, J.D. Power says, call performance and reliability has become more important over time.

“It’s no surprise that more carriers now advertise the importance of a reliable network as they try to differentiate themselves from the competition,” says Kirk Parsons, J.D. Power’s senior director of wireless services. “Wireless network quality is key in distinguishing carriers that meet and exceed the service expectations of their customers from those that do not. However, there is still room for improvement, as 31% of customers who contact their carrier with a problem complain of call quality issues, such as a high degree of dropped calls and initial disconnects.”

Wright: Latency tolerance must be considered for different applications.

QoS is so important that it even has been made part of wireless access technologies such as cdma2000 EV-DO Rev. A and UMTS/HSPA. QoS also plays a role in all of the services a carrier provides, especially voice but also data services such as video and even e-mail.

DIFFERENT USES
Just because QoS is part of the access technologies doesn’t mean carriers are using those standards. Nigel Wright, vice president of product marketing for the test and measurement company Spirent Communications, says carriers use QoS capabilities differently.

Carriers looking to deploy push-to-talk (PTT) using EV-DO Rev. A need low-latency QoS to assure VoIP calls measure up to the quality standard that the Nextel side of Sprint Nextel’s network has set, Wright says. Multiplayer games also need low latency.

Using QoS specifications, carriers can set different network standards for applications that have a higher tolerance for delay, such as streaming video that can be buffered or e-mail and Web browsing.

Qualcomm’s Qchat, which enables PTT over CDMA EV-DO networks, includes QoS software and also will take advantage of EV-DO Rev. A’s QoS features. Sprint Nextel plans on using QChat on its Rev. A network when it deploys a new PTT service in 2008, which will tie the PTT capabilities of its two networks together. Qualcomm says QChat has a call setup latency of less than one second.

UMTS network technology has similar QoS features as EV-DO Rev. A, says Wright, although he is unaware of any network using those QoS specifications yet. QoS has been in the IP network but has only recently been implemented in the radio access network equipment.

Spirent tests the handset side of QoS, but in order to do that it must emulate the network signaling, which controls QoS. The company has application-specific testing, say a PTT test system that mimics that portion of the network.

QoS also has to be implemented at many levels – supported on the handset chipsets and software, the network switches and the signaling. Everyone involved also must interpret the signaling specifications in the same way.

Wright says the CDMA operators in the United States are ahead of the UMTS carriers on implementing QoS standards in the network, but that UMTS will catch up in 2008.

QUALITY OF EXPERIENCE
QoS is equally as important in applications like streaming mobile video, an area that Ortiva Wireless plays in. Brad Hurte, marketing and product management vice president, prefers to use the term “quality of experience” for streaming video because the quality should be what the user sees.

Ortiva, whose investors include Comcast Interactive Capital and Sprint, offers technology to optimize content delivery over 2.5G and 3G networks. Its customers include GoTV, which is using Ortiva’s Mobile-CDN (content delivery network) for its on-demand video content.

Hurte says the Mobile-CDN, a hosted solution, adapts or “shapes” video or audio streams based on a user’s individual experience. Those experiences can change constantly depending on the traffic in a cell site, what kind of phone is being used, interference, handoffs and other factors. Ortiva also licenses its software alone to network operators.

The reason Hurte likes to talk about quality of experience is that he says QoS usually refers to what is done on the network, but that there are other elements to make up the user experience, such as how the handset handles streaming video, the amount of buffering, the image clarity and the appearance of smooth motion.

Wi-Fi & VoWLAN
QoS also is part of the standards for Wi-Fi and plays a role in voice over WLAN (VoWLAN) usage. Wade Williams, product management director for AirMagnet, says the company is seeing more enterprises starting to use VoWLAN because of improved performance.

AirMagnet provides end-to-end analysis and an overview of all factors affecting the voice over WLAN network.

Sunnyvale, Calif.-based AirMagnet offers technology called a VoFi Analyzer that can be used by enterprises in designing and operating a WLAN for voice calls. The analyzer proactively monitors network devices, both wired and wireless networks, QoS and an IP PBX call manager for issues that can affect VoWLAN performance.

By providing end-to-end analysis and a comprehensive overview of all factors affecting the VoWLAN network, the AirMagnet VoFi Analyzer eases VoWLAN management and according to the company makes it the most complete tool available for wireless voice analysis.

Williams says hospitals, one of the most difficult environments for wireless communications, are using voice over WLANs now. “It’s starting to be do-able if you plan and troubleshoot correctly,” he says.

The aim is to give the end-user the best possible experience. Which is what QoS is all about.