New 802.11n Wi-Fi chips unveiled at the recent Computex conference in Taipei, Taiwan, look to boost data rate, range, and link reliability, as well as improve video transmission around the home. What’s their secret? Developed by Atheros, Broadcom, Quantenna, and Ralink, they all feature 3x3 and 4x4 multiple-input multiple-output (MIMO).
Atheros Communications
The Atheros Communications AR9300 family of 802.11n solutions is based on the company’s XSPAN technology. Called Signal Sustain Technology-3, or SST3, it produces 450-Mbit/s physical-layer (PHY) rates derived from its three-stream 11n MIMO configuration. The product boosts range that sustains signal strength over a very wide area when combined with a unique set of enhancement features:
- Low density parity check (LDPC) guards against packet loss at every point on the link.
- Maximum likelihood demodulation (MLD) optimizes MIMO demodulation to boost signal strength at close range.
- Transmit beamforming (TxBF) focuses transmit signals to the receiver to enhance the link rate at mid-range on the link continuum. This technique conforms to the 802.11n standard.
- Maximal ratio combining (MRC) enables the receiver to optimally combine the MIMO signal paths, aligning time and phase of the signal receive to extend link reliability at longer range.
Backward-compatibility with 11g- and 11a/g-based devices is a given feature. Also, the AR9300 chip sets are dual-band devices covering both the 2.4- and 5-GHz unlicensed bands. Concurrent dual-band is an important feature for high-end consumer routers and enterprise access points (APs).
Using both the 2.4- and 5-GHz frequency bands multiplies the available bandwidth, maximizing the Wi-Fi network. For example, a Wi-Fi user could dedicate the 2.4-GHz band for e-mail, Web browsing, and data applications, while simultaneously using the cleaner 5-GHz band for latency-sensitive applications like video, voice, and gaming.
Thanks to MIMO, Wi-Fi is evolving to meet the stringent requirements of media-based applications like Internet Protocol television (IPTV) and whole-home video distribution. Whereas traditional wireless local-area networks (WLANs) are designed to provide the highest possible throughput for data applications, today’s media-centric networks must provide more reliable connections that minimize the number of video and audio packets lost during transmission. Packet loss and latency can lead to video glitches, unsynchronized audio, and delayed gaming responsiveness.
Finally, all of the XSPAN with SST3 devices support the Wi-Fi Direct Connect feature. As a result, notebooks can connect multimedia content directly to other client devices without transmitting through an access point. With a 450-Mbit/s PHY rate, Direct Connect transfers high-definition (HD) content simultaneously to multiple clients, while concurrently being connected to the Internet.
The AR9300 family is designed for certain products and markets. These include PCs as well as high-end laptops, home networking platforms for video, and enterprise/small business applications for dual-band Ethernet access. Specific target areas for the family members include:
- AR9380/81: single-band/dual-band Gigabit Ethernet AP/Router platforms (Fig. 1)
- AR9380: DSL, cable, set-top box, and TV carrier gateway and consumer electronics platforms
- AR9390: dual-band Gigabit Ethernet Power over Ethernet Enterprise/SMB AP/router platforms
- AR9380: dual-band PCI Express notebook and desktop platforms
Atheros is sampling the family now. Evaluation boards are available. Production is expected in the third quarter.
Broadcom
Another single-chip, 802.11n, dual-band 3x3 wireless solution comes by way of Broadcom Corp. The BCM4331, the newest member of the company’s Intensi-fi product family, targets home multimedia applications.
The Wi-Fi chip achieves 450-Mbit/s data rates in client devices and 600-Mbit/s-plus throughput (TCP/IP) in 3x3 AP/router configurations. Its high data rate combined with its range-enhancing features makes possible several wireless multimedia applications, including HD video streaming, backup, storage, multiplayer gaming, audio streaming, wireless printing, and photo sharing.
Continue to next page