Today’s Technology May Be Just the Beginning of a New Era for Wireless Media
To complete our examination of Wi-Fi over the past two months, we’ll look at what the future holds.
First we’ll consider the somewhat confusing and controversial issue of true 802.11 networking speeds, and where these speeds may be heading. Then we’ll examine the larger context what life in a wireless digital fabric may be like.
Your mileage may vary
One of the clever attributes of 802.11 networking is its ability to maintain a networked connection as link distances increase, and therefore signal strengths decrease. Like other adaptive linking systems, this is accomplished by dynamically lowering payload data rates and increasing error correction and other overhead. Wi-Fi performs these downshifts in 6 Mbps increments. This implies that actual speeds delivered to individual clients on the network may be, and usually are, substantially less than the maximum data rates cited by the networking system.
Consider also that even under optimal signal conditions, the speeds cited in 802.11 formats are burst speeds, so best-case average throughput over time ranges around 60 percent of these values (similar to peak vs. RMS power ratings). Thus, instead of operating at its quoted 11 Mbps rate, a typical 802.11b link may really be delivering 7 Mbps or less, while on a good day an 802.11g link may be cruising along effectively at around 30 Mbps instead of its full 54 Mbps.
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Moreover, in many situations, the device on the network that is furthest from the access point (but still close enough to get a viable signal) typically forces the entire network to slow down to its required speed. This means that wireless clients right next to the access point, which otherwise could blaze along at maximum speed, will have their networking bandwidth slowed down by other devices operating with lower RF signal strengths. (Lesson: Turn off or disable wireless networking on devices at long distances from access points when their connectivity is not required.)
The best solution to this is the installation of additional access point(s) for the network, closer to the location of the most distant users, so that maximum wireless path lengths in the network are reduced.
Of course, wired networking also suffers from reduced performance when usage increases, so the symptom is not unique to wireless systems, although the causes are. Most of the delays in Ethernet systems are from collision detection and avoidance, a feature not enabled in 802.11, where the delays are simply from increased overhead required on noisier paths. In any case, network users are accustomed to variable network performance.
As noted previously in this series, the typical consumer using Wi-Fi to share an Internet connection today may never notice the problem anyway, because the limiting factor is the user’s broadband connection from the ISP, which rarely exceeds 1 Mbps. But as broadband Internet access for consumers increases in speed, or as the number of wireless clients on a network increases, or, most important to this discussion, as these networks are used for in-home distribution of media content from local servers on the wireless network, this downshifting may become seriously problematic.
Hence the IEEE is not content to rest at the 54 Mbps maximum provided by 802.11a and the recently finalized 802.11g systems. Work has begun on 802.11n, which is targeting a doubling of these speeds, to 108 Mbps operation at 5 GHz, and possibly reach peak speeds of up to 320 Mbps by the time it comes to market in 2005 or 2006.
Again, the typical throughput may only reach 50 or 60 Mbps, but even this speed will allow plenty of rich media to flow across a wireless network. As before, these future systems are intended to be backward compatible to other flavors of 802.11.
Meanwhile, there are third-party systems that claim to avoid the global downshifting problem, delivering something close to full bandwidth to devices close enough to handle it, even when more-distant devices are operating at reduced rates on the same network. Such systems are not yet deployed, and it remains unclear if they will remain compliant or require proprietary extension of the standard.
Also noted earlier was that as individual Wi-Fi systems grow and intersect, their federation becomes important to avoid interference and thus optimize the efficiency of their deployment. Another future development may therefore be the emergence of an SBE-like coordination service that allows this to happen in a systematic fashion across any given region.
TV or not TV
The higher data rates mentioned become particularly interesting to wireless video applications, and have thereby gained a lot of attention recently. Yet it seems apparent that wireless networking will have a greater impact on radio services because it makes online radio more like broadcast radio (i.e., portable).
Although installation and placement becomes more convenient for TV platforms in a wireless networking context, the originally wireless nature of TV generally has been reduced in importance to consumers given the rise of cable and satellite distribution in intervening years. Radio has remained an untethered system throughout, however, and thus the constraint of a wired environment has given online radio substantially less utility than broadcast radio. This may all be about to change in short order as the Wi-Fi revolution continues.
So if you think we’ve spent a lot of ink on one topic in this column recently, it’s not without reason. This is one of the most fundamentally important technologies to come along in some time. It will undoubtedly have strong impact on the overall new media environment, and may ultimately have more effect on terrestrial radio’s future than IBOC or satellite radio does.
The cheap gets cheaper
We’ve also seen earlier how cost effective 802.11 systems are, but consider that this may just be the tip of the iceberg. Future costs likely will be reduced to negligible proportions, such that client devices may become almost “disposable.”
Some forecasters believer that this will allow all kinds of new applications, such as wireless ID tags on luggage and freight shipments, airline boarding passes, surgically implanted chips and the like. Don’t think Orwellian but rather fractally: such applications could allow intelligent, real-time communication between devices in complex systems with little or no human intervention.
Yet there will remain a wide range of requirements in this wireless world, which can be best expressed on an X-Y graph that plots message size vs. path length (see drawing). Some systems will be optimized for lightweight transmissions such as identifiers or short text messages, while others are targeted for richer data like songs, hi-res images and videos. Meanwhile, some of these containers will be carried on short-haul wireless systems designed for paths of a few to several hundred feet in length (typically unlicensed), while others will travel over longer paths (likely to more tightly regulated) that cover an entire media market or region, or even incorporate global reach.
As an example, Wi — Fi leans to the higher end of the message — size axis, and the lower end of the path-length axis, as the drawing indicates.
Naturally, some applications will link multiple systems across an end-to-end path. The 802.11 family’s IP-centric design lends itself nicely to such interfacing. The quality-of-service enhancements of IP’s next generation — IPv6 — will also be a welcome addition to such wireless applications.
Beyond Wi-Fi
Wi-Fi therefore is not for everything. Other slots on this graph will be occupied by different emerging wireless systems such as Bluetooth, Ultrawideband (UWB) and whatever 3G or 4G cellular telephony becomes – i.e., whatever is left for it to occupy after these other cheaper and more quickly deployed systems become established. FM and DTV datacasting may also play a delivery role, albeit in a unidirectional, broadcast mode as opposed to the bi-directional, point-to-point approach of true networking systems.
New regulations certainly will emerge in this environment as well. For example, the FCC has a current NOI on the possibility of assigning more unlicensed spectrum to wireless networking systems, this time on a non-interfering basis at frequencies below 1 GHz. This would allow such systems to have longer path lengths without repeating, and offer greater structural penetration. Advantageous applications of such systems would appear in rural regions and in high-density, inner-city buildings, areas where today’s 2.4 and 5 GHz systems exhibit weaknesses, and the cost of installing wired networks is prohibitive.
The commission also is examining the fascinating area of cognitive radio, in which smart two-way devices seek out currently available spectrum and establish a dynamic communication path across it, changing frequencies to avoid interference as the environment warrants, and adjusting power and bandwidth as the path length and message size requires. Watch this space for more on these developments. Meanwhile, expect Wi-Fi and its successors to rock radio’s world.
