A U.S. company (see www.atheros.com) demonstrated working 802.11a radios at the most recent N+I show in Atlanta (Radiata chips were not showable at that time).
Both companies use "standard" digital CMOS to create a two-chip 5 Ghz radio. One of the chips is all-digital and provides the DSP and OFDM modulation functions at baseband frequencies. The second chip is the 5-Ghz analog transceiver - which is the trickier bit.
The main differences between these two chip sets are first: the RF power amp is incorporated into the Atheros design - it must be an external component in the Radiata design. For indoor use in the lower 5 Ghz bands this is a 50mw device. Doing this in cmos is even trickier than the transceiver design. Secondly, the Atheros pair of chips incorporate a full NIC/MAC design into the digital chip, meaning that it has pins to hook directly onto a PCI bus or a Cardbus. The Radiata chips must be accompanied by an external MAC/bus/dma device. The Radiata digital chip will interface to a standard Intersil MAC chip, which at this time, is not able to drive the radio at full rated bandwidth (54 Mhz). The Atheros cards have been demonstrated at 72 Mhz (using two radio channels in parallel rather than just one), and are expected to achive higher bandwidths (108Mhz) in production.
Be wary of the difference between channel bandwidth and data troughput for this class of network. With ethernet and other wired LANs we're using to achieving data throughputs near the line rate. With radio protocols there is a great deal more wait time in the protocol. Current designs do well to achieve 50% of the channel. Note also that all these devices are half-duplex since it seems to be impractical to make a transceiver that can receive while transmitting (on the same channel). In the future it may very well be standard to build a chip that contains several radios operating on different channels in order to get both more bandwidth and full-duplex operation. But for now, it is not practical.
There are several frequency bands at 5Ghz set aside for non-licensed operation. The low band specifies 50 mw power at most and is intended for indoor use. Higher power levels may be used in the upper bands - up to one watt in some cases. Because of its dependence on an external power amp, the Radiata chips are well-suited for use in point-to-point external links: imagine you're Cisco and you'd like to provide wireless links between routers. In contrast, the Atheros design is solidly focused on the low-power world of laptops and home/office applicatins. In the near future one might expect a next-gen Radiata design to resemble the Atheros design, and a next-gen Atheros design to have some of the properties of the Radiata design.
Range: the range of these radios at 50mw indoors is dependent on many factors. They seem to be more robust than 802.11b - because of OFDM they are much less susceptible to multi-path interference. On the other hand the penetration through construction materials at 5 Ghz is much less than at 2.4 Ghz. Range seems to be 100-150 feet indoors - mileage will certainly vary. Signals seem to reach their destination by reflecting off walls rather than by penetration.
Summary: the Radiata chip set is a two-chip radio. The Atheros design is a two-chip NIC card that incorporates a 5-Ghz radio: just add antenna and power. Taken as a whole, these two designs represent the state-of-the-art in integrated signal processing and radio design.
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A U.S. company (see www.atheros.com) demonstrated working 802.11a radios at the most recent N+I show in Atlanta (Radiata chips were not showable at that time). Both companies use "standard" digital CMOS to create a two-chip 5 Ghz radio. One of the chips is all-digital and provides the DSP and OFDM modulation functions at baseband frequencies. The second chip is the 5-Ghz analog transceiver - which is the trickier bit. The main differences between these two chip sets are first: the RF power amp is incorporated into the Atheros design - it must be an external component in the Radiata design. For indoor use in the lower 5 Ghz bands this is a 50mw device. Doing this in cmos is even trickier than the transceiver design. Secondly, the Atheros pair of chips incorporate a full NIC/MAC design into the digital chip, meaning that it has pins to hook directly onto a PCI bus or a Cardbus. The Radiata chips must be accompanied by an external MAC/bus/dma device. The Radiata digital chip will interface to a standard Intersil MAC chip, which at this time, is not able to drive the radio at full rated bandwidth (54 Mhz). The Atheros cards have been demonstrated at 72 Mhz (using two radio channels in parallel rather than just one), and are expected to achive higher bandwidths (108Mhz) in production. Be wary of the difference between channel bandwidth and data troughput for this class of network. With ethernet and other wired LANs we're using to achieving data throughputs near the line rate. With radio protocols there is a great deal more wait time in the protocol. Current designs do well to achieve 50% of the channel. Note also that all these devices are half-duplex since it seems to be impractical to make a transceiver that can receive while transmitting (on the same channel). In the future it may very well be standard to build a chip that contains several radios operating on different channels in order to get both more bandwidth and full-duplex operation. But for now, it is not practical. There are several frequency bands at 5Ghz set aside for non-licensed operation. The low band specifies 50 mw power at most and is intended for indoor use. Higher power levels may be used in the upper bands - up to one watt in some cases. Because of its dependence on an external power amp, the Radiata chips are well-suited for use in point-to-point external links: imagine you're Cisco and you'd like to provide wireless links between routers. In contrast, the Atheros design is solidly focused on the low-power world of laptops and home/office applicatins. In the near future one might expect a next-gen Radiata design to resemble the Atheros design, and a next-gen Atheros design to have some of the properties of the Radiata design. Range: the range of these radios at 50mw indoors is dependent on many factors. They seem to be more robust than 802.11b - because of OFDM they are much less susceptible to multi-path interference. On the other hand the penetration through construction materials at 5 Ghz is much less than at 2.4 Ghz. Range seems to be 100-150 feet indoors - mileage will certainly vary. Signals seem to reach their destination by reflecting off walls rather than by penetration. Summary: the Radiata chip set is a two-chip radio. The Atheros design is a two-chip NIC card that incorporates a 5-Ghz radio: just add antenna and power. Taken as a whole, these two designs represent the state-of-the-art in integrated signal processing and radio design.