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To: Scott Zion who wrote (3841)	12/1/1999 5:34:00 PM
From: nbfm	Respond to of 13582

what about nextwave's spectrum? could a company (call it data carrier, inc.) build our nextwaves footprint for data only using hdr next year, and then lease space to other carriers (sprint, etc) on an as-needed basis? of, course, that assumes that data carrier, inc., is the high bidder at the reauction.

To: Scott Zion who wrote (3841)	12/3/1999 4:31:00 PM
From: Scott Zion	Read Replies (1) \| Respond to of 13582

Editorial on the role of TD-CDMA ------------------------------------------ wirelessdesignonline.com{5A176834-8937-11D3-9A68-00A0C9C83AFB}&Bucket=Moving+to+3G TDD to Play a Critical Role in 3G Designs 10/26/99 By: Marc Barberis, Synopsys In my last article, I presented an overview of the history of the 3G standardization efforts, starting with local organizations such as ETSI and ARIB and leading to a global standard with the emergence of the global 3G (G3G) specification (see The History of 3G?Sorting Through the Standards Battles). We have seen that the current G3G standard includes three modes: two CDMA modes (direct sequence and multi carrier) and one time-division CDMA (TD-CDMA). This month, I want to address the role of the TD-CDMA mode in 3G designs. It is interesting to note that while requirements for the future 3G systems are clear (data rate, interoperability, environment, etc.), many aspects of the deployment are still very fuzzy at best: which application to support, which mode to deploy, what will be the typical user equipment (UE) capabilities, etc. Among the most heavily debated questions is certainly the usage and application domain of the time division duplexing (TDD) mode versus the frequency division duplexing (FDD) mode. TDD weaknesses The direct-sequence CDMA (DS-CDMA) mode is considered the most applicable to medium size or larger cells. As such, it is expected to be the backbone of the first 3G systems and a lot of effort is currently being devoted to building DS-CDMA user equipment and base stations. TDD development, on the other hand, is expected to await the 2000 release of the specifications. This delay has been sparked by some concerns that have been raised about TD-CDMA systems. In particular, concerns are being tabled regarding the need for synchronization between TDD as well as the need for efficient dynamic channel allocation (DCA) procedures in order to minimize the interference level between two neighboring base stations. In addition, it is widely accepted that TDD user equipment requires the use of more complex receivers than the classical rake receiver, such as joint detectors. TDD strengths Despite their shortcomings, TD-CDMA systems do provide some advantages over FDD-based CDMA approaches. One of the major advantages of TDD technology over FDD technology is the use of unimpaired bands. This means that TDD-based systems do not require for each uplink frequency a symmetrical downlink frequency as does FDD. Currently, two paired bands of 60 MHz bandwidth have been reserved both in Europe and in Japan, together with a smaller section of unpaired bandwidth. It is, however, not unlikely that paired bands will be more difficult to find in the future, thus making the TDD mode potentially increasingly important. In addition to its unimpaired band use, TDD offers other benefits to developers of 3G systems. In particular, TDD systems offer ability to deal nicely with asymmetrical traffic. If we look at Internet browsing as being one of the major applications driving the move to 3G, it appears that the amount of downlink traffic is likely to exceed on average the amount of uplink data by a significant factor. In these applications, the FDD mode allocates as much bandwidth to the uplink and the downlink directions. Some industry members will argue that this approach provides an inefficient use of spectrum. By providing an asymmetrical scheme, TDD can devote more capacity to the downlink direction, which bears the most traffic. By doing this, industry professionals claim that the TDD approach more efficiently uses spectrum. Business issues Let?s put down the technology issues now and turn to the business issues surrounding TD-CDMA systems. In the emerging 3G world, there will be two possibilities for picocell transmission: unlicensed and licensed. Unlicensed operation means that operators are not involved. On the other hand, some spectrum packages proposed to operators in some countries do include unpaired bands where TDD is to be deployed. Hence, operators are interested in being able to deploy TDD base stations provided that: 1) the additional cost is commensurate with the additional traffic that can be accommodated or rather with the additional potential revenue, and 2)dual-mode FDD/TDD terminal are widely available, which can hand-over communications between these 2 modes. A possible licensed application of TDD would then be to alleviate the congestion at hot spots like shopping malls or airports. It is also conceivable to see TDD cells deployed where more asymmetrical traffic is expected. To conclude this discussion on TDD versus FDD modes, I wanted to mention two other emerging standards: 1) the Bluetooth initiative, which provides high data rate transmission with a very short range, which could potentially compete with some (unlicensed) TDD applications, and 2) the EDGE standard, which provides transmission up to 384 kb/s and represents an easy upgrade from GSM systems, hence looking as a promising short-term alternative to FDD systems, especially in the many countries where GSM is largely deployed. Significant efforts are being invested in developing both of these standards. When they are complete, they could possible change the face of the TDD versus FDD debate in the 3G market.