It’s hard to believe that the summer is already a distant memory. Even though I didn’t go on many photo excursions this summer, I was still able to capture a wide range of photos. I biked into Philly to get some great shots of the city, spent a night in Niagra Falls, and did some hiking in the Poconos. Enjoy
Lighting Above My Apartment. This shot was lucky, out of 100 photos only four actually captured lighting.
This was an interesting shot as at looks like morning, but actually it was pitch black and the lightning lighted the surroundings.
Niagara Falls at Dusk. I used an eight second shutter and I really like this shot as the left side of the river is peaceful while the right side is violent.
Philly!
City Hall
USS New Jersey, one of four Iowa class battle ships making it one of the most powerful battleships in the world. See the power boat along side.
Valley Forge National Park
Schuylkill River at Sun Down.
My mountain bike visiting the Liberty Bell
Hawk Mountain
How the Mountain got its name.
Today AT&T launched its 4G LTE network in five cities. While this is a big step for AT&T, its main competitor, Verizon Wireless, already launched its 4G LTE network almost ten months ago. Verizon’s 4G LTE network now has service in 143 markets and covers over half the US population. Verizon Wireless has been rapidly expanding its LTE coverage because its 3G technology is slower than AT&T’s 3G (rebranded to “4G”) technology, and thus has a shorter technological lifespan. Verizon Wireless uses EVDO rev. A for its 3G service which AT&T uses HSDPA/HSDPA+ which offers download speeds on average 2-4x faster than EVDO. Verizon Wireless and AT&T have always used different network technologies with Verizon choosing the CDMA path while AT&T electing the GSM route. While both technologies offer their share of advantages and disadvantages, going forward both companies will use the same network technology – Long Term Evolution or LTE.
LTE is not a one size fit all technology, but instead a technology that allows for a variety of different configurations which greatly impact how it is deployed and its performance. Both AT&T and Verizon Wireless utilize frequency division duplex (FDD) mode which means that the upload and download channels are on two separate frequencies. LTE also offers the capability to use time division duplex (TDD) which allows for both the download and upload channels to use one frequency with the download and upload being allocated different time slots.
Another similarity between AT&T and Verizon Wireless is that they are both utilizing 2×2 MIMO antenna technology. MIMO is an extremely complicated topic, but basically it allows double the amount of data to be transferred in a single channel by utilizing two transmit and receive antennas instead of one.
LTE release 8 supports the options for one, two, or four antenna configurations where the highest performance is achieved utilizing a 4×4 MIMO solution. Many wireless carriers are choosing the 2×2 MIMO route as it offers the best performance/price ratio. To go with a 4×4 MIMO solution over that of 2×2 MIMO means that double the number of antennas and amplifiers are needed along with more powerful processors in mobile handsets and base stations to decode the additional data streams. Additionally, MIMO only provides performance improvements when a receiver has a signal to noise ratio (SNR) of approximately 10dB or better. This means that MIMO is most beneficial when a user is close to the cell site, which for most cell sites is only a small percent of the users.
The main difference between AT&T’s and Verizon Wireless’ 4G LTE network is the bandwidth that each channel uses, and this is based on the spectrum allocation that both companies own. AT&T is using 5MHz channels while Verizon Wireless is using 10MHz channels. Given that both companies are using FDD and 2×2 MIMO this means that Verizon Wireless’ network will offer double the performance of that of AT&T’s. Theoretically, Verizon Wireless’ LTE network supports peak downlink data rates of 73Mbps while AT&T’s only supports 37Mbps. As with any wireless technology reaching anywhere near these theoretically numbers is extremely unlikely. AT&T knows that its 5MHz channels will put it at a large capacity and speed disadvantage compared to Verizon Wireless, so in markets where it has both 700MHz and AWS spectrum it is utilizing two 5MHz channels instead of just one. Currently, these two channels can’t be bonded for higher throughput, but this technology will come available in LTE Advanced and is known as carrier aggregation. The two channels become beneficial when a large number of users are on the network as the load is distributed across two 5MHz channels instead of crowding everyone into one 5MHz channel. This means under a highly loaded network scenario AT&T’s and Verizon Wireless’ should yield similar throughputs, but under normal load Verizon’s network should be vastly faster.
The final difference between the two 4G LTE networks is the base station radios used. A growing trend in the wireless industry is to mount the base station’s radio and amplifier at the top of the tower. This is known as remote radio heads (RRH) and this technology minimizes the cable attenuation experienced by an antenna system. In traditional base station deployments, the radios and amplifiers are mounted on the ground, where they can be easily upgraded and repaired, and thick coax runs up the tower to the antennas. The issue with this is that long runs of coax cable experience high attenuation and it is common to have a 2dB loss or roughly 37% less power at the top of the tower compared to when the signal left the amplifier. Clearly reducing the antenna’s output power by 37% not only reduces coverage and degrades downlink throughput, but it also affects the uplink. The antenna at the top of the power sees 37% more power from the mobile handset that what actually makes it to the base station. This result in decreases coverage, reduced uplink throughput, and diminished battery life for handsets. By mounting the radio and amplifier at the top of the top the 2dB cable loss is practically eliminated, greatly improving performance over traditional base station deployments. Instead of running thick coax up the tower, a much thinner combined fiber optic cable and power cable are run to each remote radio read.
Clearwire LTE RRH mounted to back of antenna
Clearwire’s 4G WiMAX network was the first wireless operator to solely use RRH. AT&T is following in Clearwire’s footsteps by primarily using RRH for its LTE deployment. Currently RRH can only support one technology and frequency band, so with AT&T dual frequency LTE deployment this means two RRH are needed for each face of the tower (standard is three faces per tower). Verizon Wireless stayed with the conventional base station deployment with the radios and amplifiers mounted at the bottom of the tower. The benefit of this solution is that equipment can be quickly and easily repaired and upgraded, and it is also shielded from the elements. When a RRH goes bad or needs to be upgraded it requires someone to climb the tower which can become very costly. Given that RRH technology is still very new, it will take time to see whether the performance gains of RRH make up for the limitations in easy replacement and upgradability.
Municipalities and private companies continue to realize that wind power can save them millions of dollars in electric costs. The trend started ten years ago in 2001 when Hull, Massachusetts, a small town bordering Boston Harbor installed Hull Wind 1, a 660KW Vestas wind turbine, at their high school. Just five years after the turbine was installed, the turbine was fully paid back and the town decided to install a larger 1.8MW Vestas wind turbine. Even though this new wind turbine was the largest onshore model available at the time, standing 330ft tall, the project won support as it would save the town money and benefit tax payers. In May 2006, Hull Wind 2 was installed and both wind turbines now provide more than 10% of Hull’s annual electricity.
Hull Wind 2 - 1.8MW Wind Turbine
Hull’s success has launched numerous other wind projects throughout Massachusetts. Jiminy Peak Ski Resort which I wrote about before installed a 1.5MW wind turbine in 2007 near the top of its mountain to reduce its electric costs due to operating chair lifts and snow making equipment. Rising electric costs were greatly impacting Jiminy Peak, and to remain competitive they decided a wind turbine was the perfect solution. The wind turbine which was named Zephyr now provides 33% of the resorts yearly electricity with the most electricity being produced during the winter months when it is most needed.
Jiminy Peak's 1.5MW Wind Turbine
Many communities have followed suite with the towns of Medford, Falmouth, Nantucket, and just a couple months ago Ipswich all installing large scale wind turbine. School and governments agencies have also been installing turbines including Massachusetts Maritime Academy, Holy Name High School, Massachusetts Military Reservation, and Massachusetts Water Resources Authority. As budget shortages continue, many other communities are actively investigating commercial sized wind turbines to help reduce rising electric costs. While commercial wind projects on the East Coast such as Cape Wind have faced delay after delay community based wind projects have been rapidly growing.
Nantucket High School's 100KW Wind Turbine
Last week Sprint-Nextel finally announced its LTE plans which involved teaming up with Lightsquared to build a 4G LTE network. This announcement was expected for some time, the only question that remains is what Sprint is going to do with Clearwire. Clearwire’s stock price dropped 20% on the news that it was not part of Sprint’s LTE plan. Clearwire’s market cap is now a little over $2 billion, which begs the question, who is going to buy Clearwire? One issue is that Sprint-Nextel owns a majority stake in Clearwire, which greatly complicates a takeover. Even so, Sprint-Nextel needs cash and would rather upgrade its own network than fund Clearwire to migrate from WiMax to LTE.
Clearwire has a massive amount of spectrum in the 2.5GHz band which has been estimated to be worth between $5-10 billion. The 2.5GHz band does not propagate nearly as well as the 700MHz bands which Verizon Wireless paid $4.7 billion for just a 22MHz nationwide license. This means to deploy a network at 2.5GHz with similar coverage to that of one deployed at 700MHz would require between 3x-4x the numbers of cell sites. While more cells are required to achieve similar coverage, the capacity of a 2.5 GHz network is far greater given the huge spectrum availability compared to what is available with existing 700MHz, 850MHz, PCS, and AWS bands. This makes Clearwire’s spectrum extremely valuable in dense urban environments such as New York City or sport stadiums where deploying a large amount of spectrum on the 2.5GHz band would give a wireless carrier a massive speed and capacity advantage over the competition.
In addition to Clearwire’s spectrum, its assets include a WiMax network and one of the largest microwave backhaul networks in the US. Sadly the WiMax network has not lived up to its expectations as a next generation network and performance wise it delivers similar results to that of HDSPA+ used by T-Mobile and At&t. There are few reasons to keep the WiMax network operational as it isn’t going to generate substantial revenues now that rivals are deploying LTE which has far better performance. Some of the newer the sites have equipment that can be easily upgraded to LTE, but this is still going to require a serious investment. Today Clearwire announced that it would move to LTE Advanced, but this would require an additional $600 million and something they didn’t mention is that technology wouldn’t even support LTE Advance for at least another year.
Clearwire’s microwave backhaul network paints a better picture. Clearwire has an advanced microwave network which allows it to offer a high amount of bandwidth at a fraction of the cost of traditional TDM services and in many cases fiber based solutions. This microwave network could be used to resell spare bandwidth to other carriers, as a majority of cells still use T1’s as fiber is not available at many cell locations. Overall, Clearwire’s microwave network could be quickly converted to lease spare bandwidth to other carriers which could bring in a fair amount of additional revenue. Time will tell whether Clearwire survives, but it is a potentially great buy for a wireless carrier or cable provider wanting to gobble up a huge amount of spectrum.
I recently took a trip to Chicago and brought my Panasonic ZS7 along for the journey. Chicago is a great city and the number of high rise buildings is just amazing.
