www.54g.org

What makes 54g™ products perform better than other 802.11g products?

Xpress Technology performance enhancement
SmartRadio™ for unparalleled reach and robustness
Advanced Encryption Standard (AES) encryption acceleration in hardware
Architectural support for QoS and VOIP

What performance should I expect?
54g™ products will perform differently depending on whether or not there is 802.11b traffic in the immediate environment. To ensure backwards compatibility with slower 802.11b devices, the 802.11g standard requires protection mechanisms to allow access points to manage the airspace in use by both 802.11g and 802.11b clients. This backwards compatibility comes at the expense of some loss in data throughput.

The rules-of-thumb for throughput are:

In an 802.11g-only environment, throughput will be between 4-5 times the throughput of an 802.11b network. The maximum throughput can exceed 24 Mbps. This performance is equivalent to that of 802.11a, except 802.11g can maintain high speed connections at greater distance.
In an environment that includes 802.11b devices, throughput will be about double the throughput of an 802.11b network. The maximum throughput can exceed 10 Mbps. However, 802.11g performance is still well in excess of the maximum measured speeds of 4-5 Mbps for 802.11b.

Users can get even better performance from their wireless LAN by using Broadcom's Xpress Technology. With Xpress enabled, aggregate throughput (the sum of the individual throughput speeds of each client on the network) can improve by up to 27% in 802.11g-only networks, and up to 75% in mixed networks comprised of 802.11g and 802.11b equipment.

Why are protection mechanisms important in a mixed network?
Protection mechanisms must be used to allow 802.11b clients to recognize and establish communications with 802.11g access points. The use of protection mechanism is important because it provides determinism to the wireless network, ensuring a minimum bandwidth for each user. Like Ethernet, 802.11 LANs normally use a "carrier sense media access" mechanism to signal transmission without asking for permission from the network. As the network becomes highly loaded, collisions occur more frequently and the network can become saturated with packet retransmission attempts that eventually make it impossible for any data to get through. Protection provides a more formalized flow-control mechanism that avoids this problem.

What is Xpress Technology?
Xpress Technology is Broadcom's standards-based Wi-Fi performance enhancement technology that improves wireless network efficiency and boosts throughput. It is available as a simple software upgrade for all of Broadcom's 54g, 802.11b and 802.11a/g wireless solutions.

How does Xpress Technology work?
Xpress Technology improves the efficiency and performance of the Wi-Fi network by re-packaging the data so that more of it can be sent during a given amount of time. For any transmission on a wired or wireless network, two types of packets must be sent — the desired data packets but also overhead packets that help control the network. Xpress reduces the size of the overhead packets so that more intended data can be sent over same time period, thus increasing data throughput.

Does Xpress Technology only work in 802.11g networks?
No. All wireless clients — regardless of which type of Wi-Fi technology they employ — 802.11a, 802.11b, or 802.11g — can achieve better throughput when Xpress Technology is enabled. The performance enhancements of Xpress Technology are actually most dramatic in mixed-mode 802.11b/g networks.

Does Xpress Technology improve performance for only Broadcom-based products?
No. Because Broadcom's Xpress Technology is based on the 802.11 standard, it can improve the performance of all Wi-Fi devices on the network — even if they were manufactured by another vendor and do not include Xpress Technology. After the Xpress-enabled device bursts, the non-Xpress device can still receive the burst, improving performance.

How can I take advantage of Xpress Technology?
To experience the benefits of Xpress Technology, Broadcom-based access points and/or clients must be upgraded by downloading Broadcom's latest OneDriver™ software. No hardware change is required. This updated software is now available to Broadcom's PC OEM, retail and broadband modem partners, who will enable wireless customers to upgrade existing hardware with a simple software download. End users should contact their equipment vendor for details on downloading this software.

Once an access point is upgraded, it can burst down to each client device, improving performance even if clients do not have Xpress, or vice-versa. If the Broadcom-based 802.11a, b or g clients are also upgraded with Xpress Technology, then the clients can burst back to the bursting access point, further improving overall network performance.

Will Xpress Technology help performance of my home network?
Consumers who purchase Broadcom-based solutions with Xpress Technology will get better performance and extra bandwidth. Such performance will speed up normal data transfers and may even be required for high-quality video streaming, Internet telephony and distributed audio on their home wireless network.

What does this mean for business customers?
As businesses transition their wireless networks from 802.11b to the new 802.11g standard, mixed networks (802.11b + 802.11g) will be prevalent. Fortunately, performance improvement with Xpress Technology is most dramatic when deployed in these mixed networks, thus allowing corporate customers to benefit fully from the speed of 802.11g, while still maintaining backwards compatibility with 802.11b network devices.

Many corporate networks also include mixed-mode equipment from multiple vendors. Since Xpress Technology is standards-based, all Wi-Fi devices — even non-Broadcom equipment — will achieve better throughput.

Is Xpress Technology part of the 802.11g standard?
No. Xpress Technology is based on fragment bursting in the original 802.11 standard, and is generically known as "frame bursting." Because it is defined in the higher level MAC layer, Xpress Technology can work across any type of 802.11 PHY technology, such as 802.11a, b or g. The specification has been updated and defined as Continuation TX Opportunity (CTXOP) in the forthcoming 802.11e draft specification. It is also specified in the upcoming Wireless Multimedia Enhancements (WME) draft standard, which itself is a subset of the 802.11e draft specification.

What is 802.11e?
802.11e is the IEEE draft specification for Quality of Service (QoS), and is not yet finalized. The specification provides for methods to prioritize and manage the flow of different types of communications over a Wi-Fi network. 802.11e will ensure that multimedia applications such as voice and video can run smoothly over the same Wi-Fi network that also supports normal data traffic.

What is WME?
A subset of the 802.11e draft specification, Wireless Multimedia Extensions (WME) uses four priority levels in negotiating communication between wireless access points and client devices. Prior to the ratification of 802.11e, leading wireless vendors, including Microsoft, Broadcom, and Cisco are driving the WME initiative to deliver an interim, standards-based QoS solution — much like the emergence of WPA as a subset of the forthcoming 802.11i security specification.

Why is open, standards-based technology so important?
As the computing environment becomes increasingly wireless, may more devices will be present on the wireless network, including cell phones, handhelds, notebooks, printers, cable and DSL modems, plus home entertainment devices such as TV, stereo and gaming equipment. Users will travel from home, to office, to public spaces, requiring connectivity at each location. In this increasingly Wi-Fi wireless world, seamless compatibility is critical. The only way to achieve such widespread compatibility is by ensuring that all underlying technology is built to adhere to open standards set forth by IEEE and endorsed by the Wi-Fi Alliance, the organization dedicated to certifying interoperability among Wi-Fi devices. Broadcom is an active member in the IEEE standards body, and leads multiple committees in the Wi-Fi alliance.

How does Xpress Technology differ from other performance-enhancing solutions?
The Broadcom solution is standards-based, and as a result works in mixed-vendor environments. Other solutions use proprietary methods to improve performance, requiring the same product brand for all clients and access points on the network, or the technology doesn't work. In addition, the Broadcom solution enforces a 'good neighbor' policy, meaning it does not interfere with nearby networks. Some implementations improve performance through channel bonding, which unfortunately steals all available channels, creating a 'bad neighbor' causing unnecessary harmful interference to nearby networks.

How does SmartRadio™ improve performance?
SmartRadio is Broadcom's suite of innovative radio design techniques and signal processing algorithms that improve the performance of wireless LAN devices. These include:

Continuous calibration, which tunes the wireless LAN radio on-the-fly, providing optimal performance by adjusting to changing environmental conditions. This feature also benefits OEMs by improving manufacturability.

In contrast, competitive products are usually calibrated once, by test equipment, on the manufacturing line. This traditional approach slows the manufacturing process and does not retune the radio to account for changing temperature and environmental conditions during operation.

Wireless echo reduction, which improves 802.11b range in environments with many complex surfaces, such as partitioned office spaces, airports, warehouses and homes, by using sophisticated equalization techniques to help detect the wireless LAN signal. Wireless echo reduction gives Broadcom 802.11b radios a delay spread tolerance of greater than 250 ns.

Advanced OFDM, which improves throughput in high-speed 54g™ and 802.11a systems by dynamically adapting to radio noise conditions during the signal decoding process.

Is there an advantage to hardware-based AES?
Yes. By executing the encryption/decryption in hardware, performance is improved. The alternative is to implement in software, taxing the host processor, which slows down performance.

What is WPA?
Wi-Fi Protected Access (WPA) is a specification from the Wi-Fi Alliance for standards-based, interoperable security enhancements, which strongly increase the level of data protection (encryption) and access control (authentication) for existing and future Wi-Fi wireless LAN systems. All 54g™ single-band and dual-band solutions are WPA certified.

WPA includes 802.11 as a foundation for port based network access control, authentication and key management, and Temporal Key Integrity Protocol (TKIP), an increased level of security by implementing random re-keying on WEP.

How do I design a 54g™ network for maximum performance?
54g™ products should be deployed using the same topology as 802.11b. For densely populated environments that require increased capacity or a 108 Mbps data rate, an 802.11a overlay via dual-band 802.11 a/g solutions can be deployed.