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Multi-antenna signal processing or MAS, also known as smart antennas, space-time processing, or multi-input, multi-output (MIMO), can quickly lead to detailed technical discussions, which we plan to explore in this article on specific implementations. It attempts to provide more commercial context for the drivers of adoption in 3.5G, 3G-LTE and WiMAX standards, to help system designers understand more fully why the performance gains being pursued are so critically important to the industry. Also, MAS may mean many different things to different users, but in this article we are focusing on the software part of the processing.

Wireless network operators are pursuing new sources of revenue growth as their current voice service markets become saturated, and as competition pushes down voice revenues per user (ARPU) despite rising usage. Non-voice service menus now go beyond just ring tones and SMS to include mobile video, Internet access, and myriad new applications, from on-line gambling to location-based traffic updates and m-commerce wallet functions.

The revenue share of data services in Asian markets is already on firm footing (DoCoMo in Japan^[1] and SKT in Korea^[2] both receive 27% of ARPU from non-voice services today), and the rest of the world is catching up (19% of ARPU for Vodafone in Europe, and 11 % to 12% for the major U.S. operators^{[1, 2]}). All indications point to continued solid growth ahead.

Conversation about services beyond voice often glosses over an important point. The fundamentals of subscriber economics and experience metrics for data and video are substantially different from those for voice. Figure 1 tells a stark story about the economics of data and video. Using current mass-market prices in the United States to indicate subscriber value for voice, data and video services, dividing by the capacity they consume on average for each of these media every month, yields a dramatic illustration of the differences in willingness to pay per unit of capacity consumed. The conclusion: voice, data and video services are worth roughly $1.00, $0.10 and 0.3¢ per MB to subscribers, respectively. (For reference, on-demand movies alone net out to about 0.9¢ per MB.) A wireless cost structure that supports voice will require immense changes in the long run to profitably support mass-market data and multimedia services.

And what about a “mobility premium” for these wireless services? Note that cellular voice didn't reach mainstream adoption till its prices approached those of wired telephony. Furthermore, leading indicator networks in Australia^[1] show minimal premiums for truly mobile broadband access in practice. It appears that in the long run the service premium for mobility is small.

The other fundamental difference for non-voice services is client data rate. With voice, it is difficult for a subscriber to see or hear performance beyond the largely binary feedback of “has my call been dropped?” In contrast, with high-bandwidth applications like broadband Internet access or mobile video, the new dimension of client data rate becomes immediately obvious to users. They can watch their download or upload data rate — or video frame rate and quality — climb as they approach a base station in the network and then slow to a crawl as they reach a point of minimum signal and maximum interference at the cell edge. Product or service reviewers in the press can do their own thorough performance tests, and credible word-of-mouth reports on this performance metric have already spread quickly on the Internet. This spells new stress for operators and manufacturers concerned about share positions and brand assets.

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