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Technology Stocks : The *NEW* Frank Coluccio Technology Forum

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To: Frank A. Coluccio who wrote (20188)	3/13/2007 3:36:34 PM
From: Rob S.	Read Replies (2) of 46821

WiMAX has been (until recently) positioned as n system that would be used in alternative frequency spectrum. But more recently it has made headway for consideration by ITU as an additional standard for use in IMT-2000 IP-OFDMA and for future consideration for use in IMT-Advanced. 3GPP LTE is also being proposed for IMT-Advanced. And like WiMAX/802.16e, LTE will be based on OFDM/OFDMA rather than a CDMA/WCDMA modulation scheme. And by virtue of multi-mode with 3G, it is being positioned as an enhancement or extension to existing cellular networks. Sprint is using multi-mode with EVDO as a way to leverage their existing coverage area and marketing. What this means is that whether carriers go with with either LTE or WiMAX they will need to shift to a new evolutionary platform to deliver 4G capabilities. That raises the question: 'What is 4G?'. 4G is still being defined but the most relevant description so far has been a set of goals defined by ITU that calls for per user bandwidths of 100 Mbps in mobile applications and 1 Gbps in fixed to nomadic applications. That is an aggressive set of goals: compared to 3G or current WiMAX capabilities it blows the cover off the ball. The onset of WiMAX has caused both HSDPA/HSUPA and LTE efforts to be hastened. HSDPA is here now and a few carriers (DoCoMo) are deploying HSUPA upgrades (which require new handsets to take full advantage). Prior to about 18 months ago, people in the industry we talk to indicated LTE would likely be commercial around 2012. Ericsson has led the charge to speed up the time frame and is now saying that systems will be available in 2009. A major issue is what this does for the business case for upgrades to 3.5G-3.9G WCDMA networks. Carriers who opt to upgrade networks with the latest advances in WCDMA may find the life expectancy for the big pay-day for those systems is limited by the evolution of 4G... but in reality WiMAX will take years to build the scale and momentum to cause much pain. Both WiMAX and LTE embrace a demarcation from prior systems based on CDMA. And both cannot work simultaneously in the same spectrum. Attempts to describe LTE as being evolutionary are grossly misleading: while both are new evolutionary paths for future development, LTE and WiMAX require either new spectrum or disruptive 'fork lift' upgrades of existing networks. =====> Another major question is "how can 4G's huge bandwidth goals be achieved?" Both WCDMA and OFDMA/OFDM technologies are able to achieve close to the limits of Shanon's theorem for air-link spectral efficiencies. Where are the gains over current technologies needed to deliver 100 Mbps to 1 Gbp performance going to come from? Are we going to throw out the laws of physics? Most of the expected gains are coming from the 'spatial domain' signaling methods that include MIMO, AAS (or adaptively combined MIMO-AAS) plus advances in the use of network topology including smart network capabilities. I sum this up as the 'architectural evolution' of wireless broadband. A simple way to understand the basic concept is by a look at 802.11n WiFi: 802.11n uses MIMO to achieve multi-path signaling that reuses the same spectrum along multiple signal paths. 802.11n can achieve 100 to 300 Mbps bandwidth (have not personally seen over 120 Mbps). This is possible because WiFi has a restricted range. What if 802.11n could operate over long range similar to WiMAX? If hundreds of users expected for wide area systems all communicated to a single sector/base station, the result would be a reduction of individual bandwidth. And with WiFi systems there would be massive interference as users devices contended for access. WiMAX or LTE are managed systems which are designed to better handle large umbers of users similar to current cellular networks, but they will also be subject to the same limitations of available spectrum as WiFi. And like WiFi 802.11n, the way they will achieve much higher bandwidth per user is by using the same spectrum over and over again on a tiered, intra-cell basis. Locally the network will be able to achieve very high bandwidth but the network must also be back hauled so that connections to the Internet of other network does not bcome a bottleneck. That is also true for 802.11n: while it's great to achieve 100 Mbps+ locally, if you tie into 1.5 Mbps DSL, that is all you will get when connected to the Internet. ==> Robert Syputa

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