2001 was a tough year for the proposed 802.11g standard, with endless disagreements amongst the IEEE members over how it should be implemented and a real threat that it might be abandoned altogether. Towards the end of the year a compromise was finally worked out, effectively combining elements from the principal two independent proposals that were originally considered for the 802.11g standard. Final approval won’t be granted until working versions have been tested and 90% of the voting body votes affirmatively. This is not expected to occur in before early 2003.
By May 2001 the field of candidates in the selection process had been narrowed to two; Texas Instruments’ Packet Binary Convolutional Coding (PBCC-22) proposal – offering 22 Mbit/s operation in the 2.4GHz band and seamless compatibility with existing Wi-Fi devices – and Intersil Corporation’s Complimentary Code Keying (CCK) proposal – to make use of 802.11a-like OFDM modulation to attain data rates of up to 33 Mbit/s.
In the event, neither proposal was able to gain the necessary level of support. Each of them had called for true 802.11a OFDM operation in the 2.4GHz band as an optional mode to the primary proposed modulation, either PBCC-22 or CCK-OFDM. In fact, the agreed draft standard has two mandatory modes and two optional modes, but the mandatory modulation/access modes are the same CCK (Complementary Code Keying) mode used by 802.11b (hence the compatibility with Wi-Fi) and the OFDM mode used by 802.11a (but deployed in 2.4GHz frequency band). The former supports 11 Mbit/s and the latter has a maximum of 54 Mbit/s. Both PBCC-22 and CCK-OFDM are relegated to the status of optional modes.
Since the draft 802.11g standard combines fundamental features from both 802.11a and 802.11b, it lends itself to the development of devices that can interoperate with technology based on both of the previous versions of the specification. This solves many migration path questions of users who already installed 802.11b LANs and wanted to have higher data rates, but were unsure since 802.11a was not compatible with their existing network. This can be likened to the evolution of wired Ethernet technology when Ethernet devices began supporting the 10 and 100 Mbit/s Ethernet specifications in dual-mode 10/100 devices to allow seamless operation in either mode without user intervention.
So whilst 802.11b provides a much clearer bridge between the 802.11a and 802.11b standards – plus a straightforward means for the future development of true multi-mode/RF devices – the obvious downside is that it means that the already congested 2.4GHz frequency band will get even more crowded. However, the fact is that one of the major reasons why the 802.11b standard enjoyed international acceptance was because the 2.4GHz band is almost universally available, and where there are conflicts vendors can implement frequency-selection software that prevents a radio from operating at illegal frequencies. By contrast, the 5GHz spectrum does not share this luxury.
The fact that parts of the 5GHz band are used by military applications, such as high-energy radar, has resulted in several major global markets – including Western Europe and Japan – placing regulatory restrictions on the commercial use of the band. The Japanese market shares only the lower 100MHz of the frequency spectrum, which means 802.11a applications in Japan will face more contention. In Europe, the lower 200MHz are common with the FCC’s 5GHz allotment, but the higher 5.725GHz to 5.825GHz band reserved for outdoor applications are occupied. Even in the USA – where 802.11a enjoys relatively clear-channel operation – there are questions concerning security risks for military operations.
Given that the draft standard incorporates what was formerly proprietary technologies, already at an advanced stage of development, it is possible that 802.11g solutions could begin to appear on the market as early as late-2002. However – returning to the parallel with 10/100 Mbit/s wired Ethernet – the faster standard didn’t take off until bridging products were available, and the same can be expected in the wireless networking arena. If these can be developed in a similar timeframe – possibly solving the Bluetooth problem along the way – then 2003 could be the dawn of a high-speed wireless networked world!2001 was a tough year for the proposed 802.11g standard, with endless disagreements amongst the IEEE members over how it should be implemented and a real threat that it might be abandoned altogether. Towards the end of the year a compromise was finally worked out, effectively combining elements from the principal two independent proposals that were originally considered for the 802.11g standard. Final approval won’t be granted until working versions have been tested and 90% of the voting body votes affirmatively. This is not expected to occur in before early 2003.
By May 2001 the field of candidates in the selection process had been narrowed to two; Texas Instruments’ Packet Binary Convolutional Coding (PBCC-22) proposal – offering 22 Mbit/s operation in the 2.4GHz band and seamless compatibility with existing Wi-Fi devices – and Intersil Corporation’s Complimentary Code Keying (CCK) proposal – to make use of 802.11a-like OFDM modulation to attain data rates of up to 33 Mbit/s.
In the event, neither proposal was able to gain the necessary level of support. Each of them had called for true 802.11a OFDM operation in the 2.4GHz band as an optional mode to the primary proposed modulation, either PBCC-22 or CCK-OFDM. In fact, the agreed draft standard has two mandatory modes and two optional modes, but the mandatory modulation/access modes are the same CCK (Complementary Code Keying) mode used by 802.11b (hence the compatibility with Wi-Fi) and the OFDM mode used by 802.11a (but deployed in 2.4GHz frequency band). The former supports 11 Mbit/s and the latter has a maximum of 54 Mbit/s. Both PBCC-22 and CCK-OFDM are relegated to the status of optional modes.
Since the draft 802.11g standard combines fundamental features from both 802.11a and 802.11b, it lends itself to the development of devices that can interoperate with technology based on both of the previous versions of the specification. This solves many migration path questions of users who already installed 802.11b LANs and wanted to have higher data rates, but were unsure since 802.11a was not compatible with their existing network. This can be likened to the evolution of wired Ethernet technology when Ethernet devices began supporting the 10 and 100 Mbit/s Ethernet specifications in dual-mode 10/100 devices to allow seamless operation in either mode without user intervention.
So whilst 802.11b provides a much clearer bridge between the 802.11a and 802.11b standards – plus a straightforward means for the future development of true multi-mode/RF devices – the obvious downside is that it means that the already congested 2.4GHz frequency band will get even more crowded. However, the fact is that one of the major reasons why the 802.11b standard enjoyed international acceptance was because the 2.4GHz band is almost universally available, and where there are conflicts vendors can implement frequency-selection software that prevents a radio from operating at illegal frequencies. By contrast, the 5GHz spectrum does not share this luxury.
The fact that parts of the 5GHz band are used by military applications, such as high-energy radar, has resulted in several major global markets – including Western Europe and Japan – placing regulatory restrictions on the commercial use of the band. The Japanese market shares only the lower 100MHz of the frequency spectrum, which means 802.11a applications in Japan will face more contention. In Europe, the lower 200MHz are common with the FCC’s 5GHz allotment, but the higher 5.725GHz to 5.825GHz band reserved for outdoor applications are occupied. Even in the USA – where 802.11a enjoys relatively clear-channel operation – there are questions concerning security risks for military operations.
Given that the draft standard incorporates what was formerly proprietary technologies, already at an advanced stage of development, it is possible that 802.11g solutions could begin to appear on the market as early as late-2002. However – returning to the parallel with 10/100 Mbit/s wired Ethernet – the faster standard didn’t take off until bridging products were available, and the same can be expected in the wireless networking arena. If these can be developed in a similar timeframe – possibly solving the Bluetooth problem along the way – then 2003 could be the dawn of a high-speed wireless networked world!