IEEE 802.11y-2008 - Beyond The US 3650 Band

Beyond The US 3650 Band

While the scope of 802.11y was limited to operation in the US 3650-3700 MHz band in the US, care was taken so that, if the light licensing concept was well received, it would not be necessary to start the 3+ year task group process in order for 802.11y devices to operate in other countries or in other frequency bands. As a result, lightly licensed 802.11 devices will be able to operate in any 5, 10, or 20 MHz channel that regulators make available by simply adding entries to the country and regulatory information tables in Annex I and J of 802.11.

Other potential bands for 802.11y include:

4.9 GHz - The regulatory classes and channel sizing needed to support the US public safety allocation at 4.9 GHz were added to 802.11-2007. DSE and ECSA will allow frequency coordinators to have dynamic control over channel access.

5 GHz - Regulators and equipment manufactures continue to debate the effectiveness of dynamic frequency selection (DFS) as a mechanism to avoid incumbent users in the 5 GHz bands. For example, Canada is not currently certifying 802.11 equipment for use in the 5600-5650 MHz band that is used by certain types of weather radars. 802.11y may provide a solution that will allow WLANs access to these bands. Firstly, DSE can be used to create exclusion zones around incumbent users; Secondly, when combined with DSE, the 802.11y device identification mechanism allows devices that cause interference to be denied further access to a channel within seconds.

IMT-Advanced candidate bands- (450-862, 2300-2400, 2700-2900, 3400-4200, and 4400-5000 MHz- Since 2003, The International Telecommunications Union (ITU) has been studying the potential for IMT-advanced services (aka systems beyond IMT-2000 or 4G) to use a number of frequencies between 450 and 5000 MHz for the next generation of cellular infrastructure. These systems will be capable of transmitting 100 Mb/s when mobile and 1000 Mb/s while stationary. Unfortunately, with the exception of a small amount of UHF spectrum that will become available upon the completion of the transition from analogue to digital television, these bands are occupied on a piecemeal basis by incumbent users that are not easily relocated. Extensive sharing studies have concluded that co-existence with legacy equipment over the same area is not feasible, so traditional mobile licensing approaches are not practical. Yet academic studies have shown that at any give time, even in dense urban environment, there is ample unused spectrum across the candidate bands. The problem is that usage by the primary services in these bands may change over time (as is the case with some radar systems) or vary by sub-channel based on location (as is the case in the TV bands "white spaces") 802.11y, along with the continued advances in multi-band radio technology, may provide a solution to this problem by granting channel access dynamically to users based on primary user avoidance techniques, location and time.

It is of note that the US has not been able to adopt a single position on the suitability of the 3650-3700 band for IMT-advanced, and that neither of the proposed positions seem to recognize the FCC's rules, or the standardization work that has been done to date.