MANHASSET, N.Y. — Engim Inc. (Acton, Mass.) is rolling out what it believes will be a disruptive approach to wireless LAN chip design in the form of a multi-channel, multi-band switching chipset. The chipset uses of high-end converters and advanced RF channelization and interference mitigation techniques to allow a wireless LAN (WLAN) access point (AP) to acquire three 802.11a, b, or g channels at once.
In doing so, the chipset triples an AP's throughput to 164 Mbits/s for 802.11a, though it can scale to capture up to 11 a/b/g channels simultaneously. With this throughput, the chip set is aimed to address scalability as well as the monitoring and management issues currently facing WLAN deployments.
These issues have come to the fore due to the rapid uptake of WLANs for both the enterprise and hotspots. Engim's EN-3000 chip set specifically targets these infrastructure-type applications. The company has been busy shopping its technology to a number of WLAN switch and AP vendors, many of which already have incorporated chipsets from Atheros.
Two such vendors unveiled products this week. Extreme Networks and Trapeze Networks are each offering WLAN management, mobility and security. Each have expressed an interest in a concept such as Engim's, but also expressed skepticism about how long it would take to develop and cost.
According to David Shoemaker, vice president of engineering at Engim, the EN-3000 will come in at "under $100."
Switch makers like Trapeze and Extreme have been tripping over one another recently as they move beyond the development stage. Last week, Airespace (formerly Blackstorm Networks) announced its entry into the WLAN switching arena already occupied by Bluesocket, Symbol, Proxim and more recently Nortel. Shortly, Chantry Networks will also emerge as an enterprise WLAN player, differentiated by a routing architecture rather than simply switching technology.
It is this growth that Engim is banking on to give it an edge over chip set incumbents such as Atheros, Intersil, Broadcom, Agere and soon Intel. "As the number of users grows, the enterprise is facing a scalability, capacity and RF management problem," said Shoemaker.
While placing APs in close proximity to maximize capacity has been tried, according to Shoemaker that's not an optimal approach due to interference and cabling issues. Instead, he said, "Maximizing the spectrum is an imperative as WLANs roll out."
To take advantage of the available spectrum, Engim developed a dual-band, 2.45/5-GHz architecture based on direct-conversion radios with a highly linear, low-noise front end. This is augmented by wide-dynamic-range, 12-bit, 200-Msample/s analog-to-digital converters. These are used to directly sample the full 80 MHz of spectrum available at 2.45 GHz, translating to all three non-overlapping channels of the 802.11b and .11g specifications.
In the 5-GHz band, which spans from 5.15 to 5.825 GHz with 8 channels covering 300 MHz of available spectrum, the front end can be tuned to capture any three of the 8 channels.
But capturing channels is only half the battle, according to Shoemaker. Much of Engim's intellectual property lies in the DSP algorithms used for filtering, channel separation and the mitigation of co-channel interference. A fast-Fourier transform block is included which is dedicated to processing the entire 180-MHz sampled input to provide a real-time snap shot of the spectrum that available for analysis by the upper layers. This frequency-domain snap-shot comes in fine-grain 1-MHz increments.
According to one designer who has evaluated the Engim design under non-disclosure, the advantages inherent to the EN-3000 are attractive and manifold. Particularly attractive is the ability to see exactly what was going on with the rest of the network and the flexibility that brings to the table. But again, skepticism reigns over availability and cost.
So far, only development kits are available from Engim.
