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Wireless voice over IP: What 802.11ac will do for VoIP

With the fast-approaching ratification of the IEEE 802.11ac standard, many applications that were considered throughput hogs in enterprise environments will theoretically cease to consume as many resources. In fact, depending on the processing

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power of the end device, applications heavily reliant on audio or video functionality will supposedly operate in a manner more reminiscent of Gigabit Ethernet. So right away, YouTube at Starbucks seems like a much more worthwhile proposition than in years past. In terms of unified communications, many of the implications involved with the new Gigabit Wi-Fi standard may not have been completely realized as of yet, but rest assured that voice over IP (VoIP) will find its own niche within this new technology.

Current wireless voice over IP developments

Currently, the average end user has the ability to engage in wireless VoIP calls in residential and/or Wi-Fi hotspot scenarios with profound regularity. Two of the more prominent applications used by common end users are Skype and Windows Live Messenger. While Skype has not yet made their core protocol public, a simple Wireshark capture reveals that TCP is used for the control signal, while UDP is used for data transfer. This dual utilization of TCP and UDP has gained in popularity in recent years, since it seems to compliment the older SS7 method of using a physical control signal along with a separate -- but also physical -- data signal.

In terms of performance, the real-time applications perform rather well within the IEE 802.11 standard , as long as the node–to-access point (AP) ratio remains low. However, when the network becomes too crowded, items such as Quality of Service (QoS) and overall throughput availability become adversely affected.

With the ratification of the new IEEE 802.11ac standard (Gigabit Wi-Fi) on the immediate horizon, the expectation is that some of the QoS issues found within currently crowded wireless LANs will be alleviated. The new standard supports up to eight spatial streams, as opposed to the four spatial streams supported by its predecessor, 802.11n. The increase in spatial streams will allow for less competition among nodes associated with the same AP, and it will allow wireless administrators to bond spatial streams, thereby allowing bigger pipes across the wireless spectrum. Furthermore, the 802.11ac standard operates within the 5GHz frequency band, as opposed to the 2.4 GHz band that its predecessor operates in. This will provide the wireless VoIP end user the opportunity to converse with less concern for overlapping channels than would otherwise be the case under the 802.11n standard.

Wireless voice over IP security issues

Many of the security issues with wireless VoIP have very little to do with the new standard, and therefore 802.11ac will do very little, if anything, in the way of addressing them. As with any other communication conducted wirelessly, the primary vulnerability resides in the fact that everyone within the range of the WLAN has access to the transmission medium: the air. So eavesdropping, man-in-the-middle attacks and other network attacks are only as affective as the wireless encryption protocol is weak. One area where the new 802.11ac standard will most definitely help is in the way of encryption, but not as this encryption pertains to securing the physical signal. The new standard will indirectly help with whatever encryption mechanism is used by the VoIP applications themselves. More specifically, the higher throughput available within 802.11ac will allow for faster processing of the network overhead that invariably comes with any encrypted signal. So, in the case of Skype calls, the end user may experience a considerable jump in performance, since Skype currently encrypts all calls by default. In the case of Windows Live Messenger, the end user may not notice as much of an improvement, since Messenger is unencrypted by default and therefore less consuming of network resources.

Conclusion

Wireless VoIP has gained significant amounts of traction within the small and medium-sized business market, because Cisco and other large companies have developed some fairly robust WVoIP solutions that center on actual wireless phones that associate with APs in the same way that a laptop associates with APs currently. This involves the purchase of a few other network devices, such as the Cisco Unified Communications Manager, so that the processing of wireless packets is handled more quickly and in a more orderly way. For the typical residential user however, the new 802.11ac standard should prove to be a boon to those who engage in WVoIP calls at their favorite Wi-Fi hotspots.

This was first published in April 2013

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