The residents of Cambridge, MA, may soon be able to log onto the Internet from any bus stop or city park. The city is working with MIT to go wireless, with a special focus on giving low-income residents access to the Internet.
The project is based on an experimental system called Roofnet, an unplanned, multiroute mesh network developed at MIT's Computer Science and Artificial Intelligence Laboratory. A mesh network is a series of radio transmitters and receivers randomly dispersed over an area. To get data from one part of the mesh to another, the network must figure out the best route between them, which can change depending on network traffic, data rates, and even the weather.
Roofnet has been operating for about three years across an area of roughly four square kilometers near MIT, using a few dozen transmitting/receiving nodes and one wired Internet connection through MIT. The nodes have been located in the homes and offices of volunteers, most of them MIT students and staff.
Read complete story
Tuesday, February 28, 2006
AirMagnet Wireless Security, Performance Monitoring
"As wireless LANs continue to progress towards ubiquity in enterprise and public-access settings, tools like AirMagnet Enterprise become essential," said Craig Mathias, a Principal with the wireless and mobile advisory firm Farpoint Group in Ashland, Mass. "AirMagnet is to be congratulated on integrating all of the functions required to maintain peak operational capability in large-scale deployments. I'm especially fond of their combining detailed Wi-Fi information and control with spectral analysis, a must as wireless becomes the LAN of choice for so many users and applications."
Read complete story
Read complete story
Wednesday, February 22, 2006
What is IPTV?
IPTV or Internet Protocol Television delivers digital television service to subscribers via the Internet Protocol over a broadband connection. IPTV was introduced in 1995, is gaining favor for Video on Demand, and is most recently in telco news promoted by Microsoft as the future of streaming media. IPTV services are often offered in conjunction with Video on Demand (VoD) services as well as Internet data services like Web access and Internet Telephony, or VoIP. The “Triple Play over broadband” packages VoIP phone, IPTV and internet data in one solution and is typically supplied by a broadband operator using the same infrastructure
The crux of the IPTV service is its interactivity. Therefore, unlike most legacy cable television architectures, IPTV services necessitate a two-way stream of communication between service provider/system hub and the end user. Broadband access is the delivery method that enables this streaming media interactivity. Broadband technology uses DSL (Digital Subscriber Line) over the local loop. Bell Labs arguably made IPTV possible with the invention of DSL technology in 1988. An engineer at BL discovered a way to send digital data utilizing then-unused spectrum. The local loop combined with DSL forms a star network design, as opposed to legacy cable's ring network topology.
The hub of the IPTV star is called a “Head End,” which uses DSLAM technology -- Digital Subscriber Line Access Multiplexer. IPTV's network structure allows two-way communication, point-to-point distribution. Result? The end user chooses his or her own broadcast, a true video-on-demand service. The p2p function also lets the viewer pause, rewind and replay the broadcast similar to video data on the Internet. The term "IP/TV" is an active registered United States trademark that was first owned by Precept Software, but now owned by Cisco. The IP/TV product is an audio/video system, including both servers and viewers, based on the RTP/RTCP and SDP protocols. IPTV often uses IP multicast as well. IPTV trends are expected to grow at a stunning pace over the next five years as broadband adoption grows and DSL service expands. Consumers can expect IPTV news to cover, in addition to video-on-demand movies currently offered, streaming media technology like video games on demand, TV education, interactive news with information on demand, catalogue shopping and interactive advertising.
IPTV is critical for telcos as a way to compete with cable companies, which have already penetrated the telcos' market by offering VoIP services along with their television and Internet data services.
The crux of the IPTV service is its interactivity. Therefore, unlike most legacy cable television architectures, IPTV services necessitate a two-way stream of communication between service provider/system hub and the end user. Broadband access is the delivery method that enables this streaming media interactivity. Broadband technology uses DSL (Digital Subscriber Line) over the local loop. Bell Labs arguably made IPTV possible with the invention of DSL technology in 1988. An engineer at BL discovered a way to send digital data utilizing then-unused spectrum. The local loop combined with DSL forms a star network design, as opposed to legacy cable's ring network topology.
The hub of the IPTV star is called a “Head End,” which uses DSLAM technology -- Digital Subscriber Line Access Multiplexer. IPTV's network structure allows two-way communication, point-to-point distribution. Result? The end user chooses his or her own broadcast, a true video-on-demand service. The p2p function also lets the viewer pause, rewind and replay the broadcast similar to video data on the Internet. The term "IP/TV" is an active registered United States trademark that was first owned by Precept Software, but now owned by Cisco. The IP/TV product is an audio/video system, including both servers and viewers, based on the RTP/RTCP and SDP protocols. IPTV often uses IP multicast as well. IPTV trends are expected to grow at a stunning pace over the next five years as broadband adoption grows and DSL service expands. Consumers can expect IPTV news to cover, in addition to video-on-demand movies currently offered, streaming media technology like video games on demand, TV education, interactive news with information on demand, catalogue shopping and interactive advertising.
IPTV is critical for telcos as a way to compete with cable companies, which have already penetrated the telcos' market by offering VoIP services along with their television and Internet data services.
Internet TV coming to your living room
"It's going to change the whole paradigm of advertising by opening up new ways to do it. Everything you do from changing the channel to preview, it's recorded by the service carrier so they can send back commercials that pique your interest," Dolan said. "Satellite TV's struggle hasn't posed a serious threat to cable, but I think IPTV will." The idea of IPTV is to give consumers access to TV shows broadcast around the world, or a video archive of old TV shows, sporting events and movies.
Read complete story
Read complete story
Thursday, February 16, 2006
Wireless Mesh Test Gets Underway
In the first comprehensive test of wireless mesh networking gear, sponsored by Light Reading and carried out by testing firm Iometrix Inc. , three of the leading companies in the municipal mesh networking industry are having their gear put through the paces at a specially constructed test bed in South San Francisco. Too bad the biggest players, Motorola MotoMESH, Tropos and Cisco who are the biggest players in the Mesh Networking space are not tested.
Read story from Unstrung.com
Read story from Unstrung.com
CTIA on Muni Broadband
The wireless industry association CTIA is not opposed to competition from city-sponsored, unlicensed wireless ventures, top officials of the group said. The CTIA position illustrates a shift in the unpredictable alliances in the field of municipal broadband.
read complete story
read complete story
Nokia, Motorola show cellular-VoIP phones
Nokia and Motorola, the world's biggest branded handset makers, both unveiled phones at a tradeshow here this week that switch between cellular coverage outdoors and cheap wireless Internet calling inside — all on a single phone number.
read complete story from USA Today
read complete story from USA Today
U.S. now allows full-5GHz Wi-Fi networking
By Joanie Wexler
Last month, the FCC officially opened up the use of the middle band of the Unlicensed National Information Infrastructure (UNII) spectrum (5.470 GHz to 5.725 GHz) to 54Mbps 802.11a Wi-Fi networks in the United States. The band adds another 255 MHz and 11 channels to the existing 325 MHz and 13 channels available for Wi-Fi in this band.
As of January 20, any products that apply for certification in the 5.470 GHz to 5.725 GHz band or in the lower end of the UNII band at 5.25 GHz to 5.35 GHz, were required to support dynamic frequency selection (DFS) and transmit power control (TPC) to minimize interference, per a February 2005 FCC order.
If you've already got equipment running in the lower band installed, don't worry - you're grandfathered.
DFS and TPC are part of 802.11h, the European "flavor" of 802.11a. DFS dynamically instructs a transmitter to switch to another channel under particular conditions, such as the presence of a radar signal.
Setting the transmit power of the access point and the client adapter can allow for different coverage area sizes and for the client to conserve battery life. For example, it helps to reduce transmit power in areas with high user density to avoid interference. It can also help with security by keeping transmit ranges confined so there is less chance of signals spilling out into the street or to neighboring offices.
Both the 5-GHz and 2.4-GHz spectrum ranges are likely to be component of future 802.11n networks. While the 5-GHz range has its issues with inconsistent global regulation (see Monday's newsletter), the 2.4-GHz band supporting 802.11g and 802.11b faces its own hurdles. I'll discuss those next time.
February 2005 FCC order
Last month, the FCC officially opened up the use of the middle band of the Unlicensed National Information Infrastructure (UNII) spectrum (5.470 GHz to 5.725 GHz) to 54Mbps 802.11a Wi-Fi networks in the United States. The band adds another 255 MHz and 11 channels to the existing 325 MHz and 13 channels available for Wi-Fi in this band.
As of January 20, any products that apply for certification in the 5.470 GHz to 5.725 GHz band or in the lower end of the UNII band at 5.25 GHz to 5.35 GHz, were required to support dynamic frequency selection (DFS) and transmit power control (TPC) to minimize interference, per a February 2005 FCC order.
If you've already got equipment running in the lower band installed, don't worry - you're grandfathered.
DFS and TPC are part of 802.11h, the European "flavor" of 802.11a. DFS dynamically instructs a transmitter to switch to another channel under particular conditions, such as the presence of a radar signal.
Setting the transmit power of the access point and the client adapter can allow for different coverage area sizes and for the client to conserve battery life. For example, it helps to reduce transmit power in areas with high user density to avoid interference. It can also help with security by keeping transmit ranges confined so there is less chance of signals spilling out into the street or to neighboring offices.
Both the 5-GHz and 2.4-GHz spectrum ranges are likely to be component of future 802.11n networks. While the 5-GHz range has its issues with inconsistent global regulation (see Monday's newsletter), the 2.4-GHz band supporting 802.11g and 802.11b faces its own hurdles. I'll discuss those next time.
February 2005 FCC order
Wednesday, February 15, 2006
MOTOwi4(TM) WiMAX portfolio
Key access networks in the MOTOwi4 portfolio include WiMAX, Canopy, backhaul, and Mesh Solutions. MOTOwi4 Canopy is a proven broadband wireless access solution that has been cost-effectively deployed in more than 100 countries -- including a country wide deployment in Macedonia -- and by more than 2,000 service providers since 2002 using 2.4GHz and 5GHz frequencies. In the Macedonia deployment, an initial installation of more than 130 Canopy access points at various schools now also serves consumers and businesses in 36 cities and 170 villages. Altogether, that Canopy network has connected 360 primary and 100 secondary schools as well as 24 secondary school dormitories, 15 university facilities, another 15 local government offices, and more than 1,000 businesses, bringing high-speed wireless connectivity to rural and urban areas at price points that would not otherwise have been attainable.
Canopy technology, designed for unlicensed or managed spectrum, also enables WiMAX services supporting VoIP and IP data applications at price points that can meet customers' business case requirements.
The MOTOwi4(TM) WiMAX portfolio will include 802.16e products designed to meet WiMAX Forum(TM) certification based upon specific profiles to be developed by that industry forum. Operating in licensed spectrum and standards-based following IEEE 802.16 Rev e, Motorola's MOTOwi4 WiMAX products are designed to permit carriers to adopt the full scope of available fixed, nomadic, portable, and mobile applications. The initial product, the MOTOwi4 UltraLight Access Point designed for 3.5GHz and a fixed application, will be 802.16e compliant. It is expected to be available for customer trials by the end of Q2 2006.
Read the full story
Canopy technology, designed for unlicensed or managed spectrum, also enables WiMAX services supporting VoIP and IP data applications at price points that can meet customers' business case requirements.
The MOTOwi4(TM) WiMAX portfolio will include 802.16e products designed to meet WiMAX Forum(TM) certification based upon specific profiles to be developed by that industry forum. Operating in licensed spectrum and standards-based following IEEE 802.16 Rev e, Motorola's MOTOwi4 WiMAX products are designed to permit carriers to adopt the full scope of available fixed, nomadic, portable, and mobile applications. The initial product, the MOTOwi4 UltraLight Access Point designed for 3.5GHz and a fixed application, will be 802.16e compliant. It is expected to be available for customer trials by the end of Q2 2006.
Read the full story
Monday, February 13, 2006
IP Telephony in Fighter Jet
IP Telephony Takes Flight with U.S. Fighter Jet
February 9, 2006
IP Telephony has taken to the skies, linking an F-15E fighter jet in flight with a remote government command center in California and a three-star general at the Pentagon via a multi-party, IP conference call.
The test was successfully conducted at the Naval Air Weapons Center in China Lake, Calif., for the Defense Advanced Research Projects Agency (DARPA) — the central research and development organization for the Department of Defense. During the test, Avaya demonstrated a multiparty IP conference call connecting the aircraft's weapon systems officer with two parties at the China Lake Integrated Battlespace Arena Command Center and with Lt. Gen. William T. Hobbins at his desk in the Pentagon in Washington, D.C.
"The call lasted for more than 20 minutes, and the audio quality was excellent," said Ryan Greene, a Boeing engineer who worked on the test with Avaya and participated in the call.
In addition to the multiparty conference call, successful tests were completed using Avaya's IP telephony network to call an in-flight, E-2C Hawkeye surveillance aircraft equipped with an Avaya IP Softphone.
"Being able to call a tactical aircraft from anywhere in the world and vice versa is a critical combat capability unprecedented with legacy communications," said Lt. Col. Stephen Waller, USAF, DARPA program manager for the Tactical Targeting Network Technology program.
Communication has previously been limited to two-party calls using 'push to talk' radios, with critical information relayed from one party to the next. With IP telephony, all those involved can speak naturally and communicate dynamically, in real time — from the Air Operations Center to targeting and safety crews, with simultaneous transmission of actual local ground and/or aircraft data. The end result is quicker and better decision making and improved safety for U.S. pilots on the front lines.
Both tests used Avaya's Communication Manager IP telephony software hosted on an Avaya Media Server. Avaya Session Initiation Protocol (SIP) Enablement Services were used to ensure connectivity with standards-based endpoints for telephony, instant messaging, conferencing and collaboration. The multiparty conference call involved both an Avaya IP phone and an Avaya SIP IP telephone at China Lake and a traditional desk set at the Pentagon. A third-party SIP softphone running on a Windows-based auxiliary computer was used in the F-15E cockpit, connecting the pilot to the conference via a secure wireless link.
The wireless connectivity for Avaya's IP telephony network was provided by a Tactical Targeting Network Technology (TTNT) demonstrated during the tests. TTNT is an IP-based technology that connects tactical aircraft and ground operations to enable real-time communications. The F-15E was provided for the test by Boeing, while the E-2C Hawkeye was provided by the U.S. Navy.
The DARPA tests are part of the preparations for the upcoming 2006 Joint Expeditionary Force Experiment (JEFX) administered by the U.S. Air Force. As a next step, Avaya has collaborated with Boeing to develop specialized IP telephony software for the F/A-18 aircraft that will be part of the 2006 JEFX. In addition, Avaya Labs has developed a SIP toolkit that is allowing Boeing to integrate a SIP softphone into the F/A-18 aircraft, which will allow the pilot or weapon systems officer to communicate via a secure wireless link.
Avaya was first selected by the Air Force in an initiative for the biennial JEFX in 2004. Features of Avaya Communication Manager IP telephony software designed to specifically support the government's mission include:
* Avaya Multiple Level Precedence and Preemption capabilities that allow
officials to override nonessential calls during times of emergency
* "Blast dialing" capabilities that can quickly establish preset
conference calls among critical contacts.
In addition, Avaya IP telephony solutions were the first in the market to be certified by the government's Joint Interoperability Test Command for use in critical military command and control missions worldwide.
Read the full story
February 9, 2006
IP Telephony has taken to the skies, linking an F-15E fighter jet in flight with a remote government command center in California and a three-star general at the Pentagon via a multi-party, IP conference call.
The test was successfully conducted at the Naval Air Weapons Center in China Lake, Calif., for the Defense Advanced Research Projects Agency (DARPA) — the central research and development organization for the Department of Defense. During the test, Avaya demonstrated a multiparty IP conference call connecting the aircraft's weapon systems officer with two parties at the China Lake Integrated Battlespace Arena Command Center and with Lt. Gen. William T. Hobbins at his desk in the Pentagon in Washington, D.C.
"The call lasted for more than 20 minutes, and the audio quality was excellent," said Ryan Greene, a Boeing engineer who worked on the test with Avaya and participated in the call.
In addition to the multiparty conference call, successful tests were completed using Avaya's IP telephony network to call an in-flight, E-2C Hawkeye surveillance aircraft equipped with an Avaya IP Softphone.
"Being able to call a tactical aircraft from anywhere in the world and vice versa is a critical combat capability unprecedented with legacy communications," said Lt. Col. Stephen Waller, USAF, DARPA program manager for the Tactical Targeting Network Technology program.
Communication has previously been limited to two-party calls using 'push to talk' radios, with critical information relayed from one party to the next. With IP telephony, all those involved can speak naturally and communicate dynamically, in real time — from the Air Operations Center to targeting and safety crews, with simultaneous transmission of actual local ground and/or aircraft data. The end result is quicker and better decision making and improved safety for U.S. pilots on the front lines.
Both tests used Avaya's Communication Manager IP telephony software hosted on an Avaya Media Server. Avaya Session Initiation Protocol (SIP) Enablement Services were used to ensure connectivity with standards-based endpoints for telephony, instant messaging, conferencing and collaboration. The multiparty conference call involved both an Avaya IP phone and an Avaya SIP IP telephone at China Lake and a traditional desk set at the Pentagon. A third-party SIP softphone running on a Windows-based auxiliary computer was used in the F-15E cockpit, connecting the pilot to the conference via a secure wireless link.
The wireless connectivity for Avaya's IP telephony network was provided by a Tactical Targeting Network Technology (TTNT) demonstrated during the tests. TTNT is an IP-based technology that connects tactical aircraft and ground operations to enable real-time communications. The F-15E was provided for the test by Boeing, while the E-2C Hawkeye was provided by the U.S. Navy.
The DARPA tests are part of the preparations for the upcoming 2006 Joint Expeditionary Force Experiment (JEFX) administered by the U.S. Air Force. As a next step, Avaya has collaborated with Boeing to develop specialized IP telephony software for the F/A-18 aircraft that will be part of the 2006 JEFX. In addition, Avaya Labs has developed a SIP toolkit that is allowing Boeing to integrate a SIP softphone into the F/A-18 aircraft, which will allow the pilot or weapon systems officer to communicate via a secure wireless link.
Avaya was first selected by the Air Force in an initiative for the biennial JEFX in 2004. Features of Avaya Communication Manager IP telephony software designed to specifically support the government's mission include:
* Avaya Multiple Level Precedence and Preemption capabilities that allow
officials to override nonessential calls during times of emergency
* "Blast dialing" capabilities that can quickly establish preset
conference calls among critical contacts.
In addition, Avaya IP telephony solutions were the first in the market to be certified by the government's Joint Interoperability Test Command for use in critical military command and control missions worldwide.
Read the full story
Google and Skype to link hotspots, charge for access
Google and Skype invest in startup to link hotspots, charge for access
Google Inc. and eBay Inc.'s Skype are investing in a startup that plans to help hotspot owners charge for Wi-Fi access, a plan that could face significant opposition from Internet service providers.
The Internet heavyweights were joined by venture capital firms Index Ventures and Sequoia Capital in making a $22 million (?18.24 million) investment in FON, the Spanish startup. In its announcement Sunday, FON did not say how much each investor was contributing.
Read the full story
Google Inc. and eBay Inc.'s Skype are investing in a startup that plans to help hotspot owners charge for Wi-Fi access, a plan that could face significant opposition from Internet service providers.
The Internet heavyweights were joined by venture capital firms Index Ventures and Sequoia Capital in making a $22 million (?18.24 million) investment in FON, the Spanish startup. In its announcement Sunday, FON did not say how much each investor was contributing.
Read the full story
Friday, February 10, 2006
Nintendo's Wi-Fi connection service
Nintendo's Wi-Fi connection service has revolutionised handheld gaming byallowing anyone to play against friends from across the globe, simply, safely and for free, either at home or on the go. There is no fee to pay and no difficult set-up procedures - gamers simply insert their Wi-Fi enabled game into their Nintendo DS, within a Nintendo Wi-Fi connection hotspot, and press connect. Nintendo DS owners can also enjoy Wi-Fi gaming from the comfort of their homes using their existing Wi-Fi broadband connection. People can play without fear of harassment from other players as they can choose to play only with their friends.
As part of its ongoing drive to provide free Wi-Fi access to Nintendo DS owners Nintendo has signed deals with major Wi-Fi providers across Europe giving users access to over 20,000 free Nintendo Wi-Fi access points.
Read the full story
As part of its ongoing drive to provide free Wi-Fi access to Nintendo DS owners Nintendo has signed deals with major Wi-Fi providers across Europe giving users access to over 20,000 free Nintendo Wi-Fi access points.
Read the full story
Europe’s Largest Wi-Fi Deployment
"We had to select a reliable mobile software platform able to support our highly demanding requirements. The system must run 365 days per year, 24 hours per day, and support 10,000 users scattered through out the country in over 50 stations," said Wim Liet, Head Business Applications, NS Reizigers Production Services.
Full Story
Full Story
Thursday, February 09, 2006
Lucent adds Cellular/Wi-Fi roaming
I really like this new software applicatins from PCTEL-Lucent. With this application a smartphone could switch between cellular and Wi-Fi nets while maintaining a voice call or data session, without the user being aware of the change. Seamless transition from Cellualr to WiVOIP.
Read the full story
Read the full story
Tuesday, February 07, 2006
Tax on Wireless Technology
The 2007 budget plan from the Bush administration has proposed supporting legislation changes to allow the Federal Communications Commission (FCC) to set 'user fees' on unlicensed radio spectrum in the US. This appears to be a good for licsened broadband in the 4.9 frequncy.
Though unclear on whether the fees would be paid by equipment vendors or end-users, the statement basically means a tax on equipment such as WLAN routers, cordless phones, and mobile phones with technology such as Bluetooth.
Read the full story
Though unclear on whether the fees would be paid by equipment vendors or end-users, the statement basically means a tax on equipment such as WLAN routers, cordless phones, and mobile phones with technology such as Bluetooth.
Read the full story
802.11n backward compatibility
By Joanie Wexler
It has been widely reported that 802.11n, the wireless LAN IEEE draft standard that uses multiple input/multiple output technology to boost Wi-Fi speeds to over 100Mbps, is "backward compatible" with today's 802.11a, 11b, and 11g networks. This can seem confusing, given that 802.11a, which runs in the 5-GHz frequency band, is not compatible with 802.11g and 11b, which operate in the 2.4-GHz band.
So how can 11n be backward compatible with all these networks, when they are not compatible with each other?
5-GHz networking support is currently an optional component to the 802.11n draft standard. As such, the MIMO scheme of 802.11n does not require simultaneous use of both the 5-GHz and the 2.4-GHz bands, according to Mark Hung, director of strategic marketing at Wi-Fi chipmaker Atheros. That's how a standard that potentially makes use of both bands can be backward-compatible with networks that use a single band only: Only one band is in use at a time.
For interoperability, 802.11n supports three modes, explains Hung:
* Legacy mode.
Addresses 11n APs and an 11a/g/b client environment. In this case, the client decodes the first three fields of a six-field header, which is specific to 11a and 11g. If the 5-GHz option isn't supported in the 11n AP, there will be no backward compatibility with 802.11a.
* Mixed mode.
Addresses 11n APs and a mixed 11n/a/g/b environment. As in legacy mode, 11a and 11g/b clients will read the first three fields of the AP's 11n header, while 802.11n will also parse the additional three "high throughput" fields of the full 11n header. Again, if the 5-GHz option isn't supported in the 11n AP, there will be no backward compatibility with 802.11a.
* Greenfield mode.
Addresses a pure network of 802.11n APs and clients, taking full advantage of the high-throughput capabilities of the 11n MIMO architecture.
What if you have some 802.11a/g APs, and some 802.11n clients creep into the picture?
Because MIMO technology leverages multiple pairs of antennas to boost speed, 11n clients mixed with 11a/g networks should experience a 30% to 50% improvement in either range or throughput, Hung says because of the client's "extra pair of ears."
In the wake of 802.11n being approved as an IEEE draft specification last month, both Atheros and competing chipmaker Broadcom have announced the availability of 802.11n chips that will be software-upgradeable to comply with the final specification. Both support the 5-GHz option, which much of the industry agrees is needed to deliver the 40-MHz of spectrum in adjacent spectrum required for 11n's promised speeds.
Contact the author:
Joanie Wexler is an independent networking technology writer/editor in California's Silicon Valley who has spent most of her career analyzing trends and news in the computer networking industry. She welcomes your comments on the articles published in this newsletter, as well as your ideas for future article topics. Reach her at joanie@jwexler.com.
My site needs updating
It has been widely reported that 802.11n, the wireless LAN IEEE draft standard that uses multiple input/multiple output technology to boost Wi-Fi speeds to over 100Mbps, is "backward compatible" with today's 802.11a, 11b, and 11g networks. This can seem confusing, given that 802.11a, which runs in the 5-GHz frequency band, is not compatible with 802.11g and 11b, which operate in the 2.4-GHz band.
So how can 11n be backward compatible with all these networks, when they are not compatible with each other?
5-GHz networking support is currently an optional component to the 802.11n draft standard. As such, the MIMO scheme of 802.11n does not require simultaneous use of both the 5-GHz and the 2.4-GHz bands, according to Mark Hung, director of strategic marketing at Wi-Fi chipmaker Atheros. That's how a standard that potentially makes use of both bands can be backward-compatible with networks that use a single band only: Only one band is in use at a time.
For interoperability, 802.11n supports three modes, explains Hung:
* Legacy mode.
Addresses 11n APs and an 11a/g/b client environment. In this case, the client decodes the first three fields of a six-field header, which is specific to 11a and 11g. If the 5-GHz option isn't supported in the 11n AP, there will be no backward compatibility with 802.11a.
* Mixed mode.
Addresses 11n APs and a mixed 11n/a/g/b environment. As in legacy mode, 11a and 11g/b clients will read the first three fields of the AP's 11n header, while 802.11n will also parse the additional three "high throughput" fields of the full 11n header. Again, if the 5-GHz option isn't supported in the 11n AP, there will be no backward compatibility with 802.11a.
* Greenfield mode.
Addresses a pure network of 802.11n APs and clients, taking full advantage of the high-throughput capabilities of the 11n MIMO architecture.
What if you have some 802.11a/g APs, and some 802.11n clients creep into the picture?
Because MIMO technology leverages multiple pairs of antennas to boost speed, 11n clients mixed with 11a/g networks should experience a 30% to 50% improvement in either range or throughput, Hung says because of the client's "extra pair of ears."
In the wake of 802.11n being approved as an IEEE draft specification last month, both Atheros and competing chipmaker Broadcom have announced the availability of 802.11n chips that will be software-upgradeable to comply with the final specification. Both support the 5-GHz option, which much of the industry agrees is needed to deliver the 40-MHz of spectrum in adjacent spectrum required for 11n's promised speeds.
Contact the author:
Joanie Wexler is an independent networking technology writer/editor in California's Silicon Valley who has spent most of her career analyzing trends and news in the computer networking industry. She welcomes your comments on the articles published in this newsletter, as well as your ideas for future article topics. Reach her at joanie@jwexler.com.
My site needs updating
Friday, February 03, 2006
Public Access Muni WiFi vs Public Safety Muni Mesh Networks
Every day more and more news comes out about cities and towns looking build city wide WiFi networks. The growth of WiFi has created wireless internet connectivity options in many places. It has made it convenient to check email and browse the web. Companies like Tropos have deployed WiFi Mesh networks across the US that are used for Public Access but can also give public safety police and fire personnel to a high speed mobile data network. In the past public safety has relied on slower mobile data systems that have prevented more bandwidth intense applications from being used.
I do not agree it is a good thing to have public safety using the same wireless infrastructure as the general public use for WiFi access. Even you can agrue that a secure VPN tunnel across this open WiFi connection can be created, you are still using a unlicensed 2.4 spectrum and are sharing network resources with the general public. In my opinion deploying a private infrastructure 4.9 WiFi network using a licensed spectrum is the best choice.
I do not agree it is a good thing to have public safety using the same wireless infrastructure as the general public use for WiFi access. Even you can agrue that a secure VPN tunnel across this open WiFi connection can be created, you are still using a unlicensed 2.4 spectrum and are sharing network resources with the general public. In my opinion deploying a private infrastructure 4.9 WiFi network using a licensed spectrum is the best choice.
Intelsat inks contract with Qualcomm for mobile TV
"Under the Qualcomm deal, expected to be formally announced on Monday, Intelsat will use its satellites to beam video programing to cell phone broadcast towers that Qualcomm's MediaFlo unit is building to send live TV to phones."
I don't have time to watch TV, so now I can watch on my cell phone. Still need a high speed data network stream content.
Read the full story
I don't have time to watch TV, so now I can watch on my cell phone. Still need a high speed data network stream content.
Read the full story
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