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News
Issue #2003 - 04 (February 2003)
(Updated Feb. 5, 2003)

TECHNOLOGY

WiFi News

1. 1. AT&T Wireless joins hot spot fray
AT&T Wireless, the third largest wireless phone company in the U.S., today introduced its new hot spot service, named GoPort. So far, the service is deployed only at Denver International airport, but the company has reached an agreement to install the service in Philadelphia International soon. AT&T Wireless has also entered a roaming agreement with Wayport, so GoPort users can access the Wayport network as well. Wayport now offers hot spots at airports in Austin and Dallas, Texas; San Jose, California; and Seattle/Tacoma, Washington. Wayport has roaming agreements with GRIC, iPass, and Boingo Wireless, and AT&T Wireless will integrate these agreements into GoPort. GoPort does not require a special client for access. Users should note, however, that to connect to a GoPort hot spot, the client cards must have the WEP encryption turned off and use Dynamic Host Configuration Protocol (DHCP) to obtain an IP Address (the SSID is "AT&T Wireless"; if roaming on a Wayport network, it is "Wayport_Access"). The pricing structure is a bit elaborate (and not cheap): 24-hour connection periods are called "connections"; a single connection is $9.99; five connections are $29.99; 10 connections are $49.99 (all connections must be used within 180 days of the first connection). An unlimited monthly usage goes for $69.99. These prices are about 25-30 percent more expensive than equivalent subscription packages from Wayport.

2. IBM includes dual 802.11a/b in Thinkpad
IBM has decided to include a dual chip 802.11a/b in its new Thinkpad R40. IBM will also offer 802.11b-only models, and models that can be upgraded later. The R40 includes an antenna built into the display cover for best WLAN signal reception, and the dual-band models also feature the IBM Access Connections location-manager utility, which automatically switches network settings when users move from a wired connection to a WLAN connection. ThinkPad R40 is equipped with both WLAN technology and IBM's Embedded Security Subsystem (ESS) supports 802.1x authentication credentials, such as digital certificates, with the security subsystem. 802.11 a/b models also include Cisco LEAP support. The ThinkPad R40 is available now at prices ranging from $979 for a model with a 1.6GHz Intel Celeron processor to $1,499 for one with a 2.0 GHz Intel Pentium 4 processor. 

3. First 802.11a products receive Wi-Fi Certified seal
Go to WiFi news item in this week's news flash.

4. 1. Senators push to expand 802.11a allocation
In a major boost to 802.11a, Senator George Allen (R.-Va.) and Senator Barbara Boxer (D.-Calif.) last night introduced the Jumpstart Broadband Act, a piece of legislation the two senators claim would foster a more favorable climate for a more robust wireless deployment. Specifically, the bill calls on the Federal Communications Commission (FCC) to allocate at least 255 MHz of additional -- and contiguous -- spectrum in the 5 GHz band for unlicensed use by wireless devices. The legislation also instructs the FCC to stipulate threshold rules of interference protection for devices in the 5 GHz spectrum and ensure that Department of Defense systems operating in that spectrum are not compromised. To understand the importance of the proposed legislation, we should briefly look at the 802.11a specifications.
Allocation: The FCC allocated 802.11a 300 MHz of spectrum in the 5 GHz band. The 300 MHz allocation is not contiguous: 200 MHz are at 5.15 MHz to 5.35 MHz, and 100 MHz are at 5.725 MHz to 5.825 MHz. The spectrum is further split into what may be called three working domains, with different power outputs allowed:

  • The first 100 MHz in the lower section is restricted to a maximum power output of 50 mW (milliwatts); 
  • The second 100 MHz is allowed a maximum of 250-mW power output; 
  • The top 100 MHz is designed for outdoor applications and allowed a maximum of 1-watt power output.

(802.11b cards are allowed to radiate as much as 1 watt).
The total bandwidth available for 802.11a applications is almost four times the total given to 802.11b: 802.11b is allowed only 83 MHz of spectrum in the 2.4 GHz range, while 802.11a is allocated 300 MHz in the 5 GHz range (albeit, segmented 300 MHz). 

Power: Frequency, radiated power, and distance are related to each other in an inverse relationship by the laws of information theory: Moving up from 2.4 GHz to the 5-GHz spectrum leads to shorter transmission distance, given the same radiated power and encoding scheme. To compensate for this short-fall, manufacturers specified a new physical-layer encoding technology for 802.11a different from the two spread spectrum technologies used by 802.11b -- direct-sequence spread spectrum (DSSS), and frequency hopping spread spectrum (FHSS). The technology used by 802.11a is orthogonal frequency division Multiplexing (OFDM). OFDM breaks one high-speed data carrier into several lower-speed subcarriers, which are then transmitted in parallel. Each high-speed carrier is 20 MHz wide, and is further broken up into 52 subchannels, each about 300 KHz wide. OFDM uses 48 of these subchannels for data (the other four are used for error correction). It is possible to increase or decrease the data transmission rate per channel: thus, on the low-speed-per-channel side, binary phase shift keying (BPSK) is used to encode 125 Kbps of data per channel, resulting in a 6,000-Kbps, or 6 Mbps, data rate. If, for example, we use 16-level quadrature amplitude modulation encoding 4 bits per hertz, it would be possible to achieve a data rate of 24 Mbps, and so on.

The bill introduced by the two senators will expand the band allocated to 802.11a in the 5 GHz range from 300 MHz to 555 MHz, of which 255 MHz will be contiguous. The two senators argued that innovations and advances in the development of unlicensed wireless, radio-based networks offer not only additional ways to deliver data at high speed, but also allow new business models for delivering broadband connectivity to emerge. Senator Allen said that the bill would force Congress to rethink the broadband distribution debate -- changing it from a debate over DSL vs. cable into a debate which considers "that alternative modes or other technologies are available that can jumpstart consumer-driven investment and demand in broadband services."

If the legislation passes, its most immediate result will be to ease negotiations between the United States and Japanese and European regulators aimed at finding a universally accepted standard for 802.11a. In the next issue we will examine the technological -- and consumer-related -- consequences of the proposed legislation.

Source - Several, including 802.11 portal

MobileInfo Comments and Advisory: WiFi continues to move forward at a fast clip. Future will not be without it. Note FCC has blessed it. Even the pentagon has figured out how to resolve WiFi's interference problems. WiFi should be part of your future. 

Note: This news release may contain forward-looking statements within the meaning of section 27A of the Securities Act of 1933 and section 21E of Securities Exchange act of 1934 in USA. Similar provisions exist in other countries. There is no assurance that the stipulated plans of vendors will be implemented. MobileInfo does not warrant the authenticity of the information. Readers should take appropriate caution in developing plans utilizing these products, services and technology architectures.  All trademarks used in this summary are the property of their respective owners.


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