4. Wireless Local Networks

4.1 Background

4.2 Overview

4.3 Review of 902 to 928MHz

4.4 Conclusions for 902 to 928MHz

4.5 Review of 2400 to 2483.5MHz

4.6 Conclusions for 2400 to 2483.5MHz

4.7 Review of 3650 to 3700MHz

4.8 Conclusions for 3650 to 3700MHz

4.9 Overview of 5150 to 5875MHz

4.1 Background

Wireless Local Area Networks or WLANs have experienced rapid growth and development in recent years. This has been assisted by the alignment of the international spectrum allocations and technical specifications in the major trading nations. There are a variety of different implementations from local short-range systems to large metropolitan wide networks.

The term WLANs is used in this paper to include RLANs, WMANs, WiFi, WiMAX, 802.11, 802.16, HIPERLAN and other similar terms used in the industry.

The current and proposed international spectrum bands for WLANs are

• 902 to 928MHz,
• 2400 to 2483.5MHz
• 3650 to 3700MHz and
• 5150 to 5875MHz.

The degree of international harmonisation varies with each band.

4.2 Overview

The ITU-R Recommendation SM.1538 3 makes note of Broadband Radio Local Area Networks but does not provide any specific guidance on their spectrum allocation.

At the ITU-R conference WRC 03, Resolution 229 4 was passed which gives specific details for the operation of wireless access systems in some 5GHz bands. The full text of Res. 229 is provided in Appendix C and the implications are detailed in the following sections.

There is considerable ongoing work in various international and regional forums to develop new standards which will provide enhanced services and facilitate further international standardisation. In particular High-speed Unlicensed Metropolitan Wide Area Networks based on the IEEE specification 802.16 5 and the European ETSI standard HIPERMAN.6

4.3 Review of 902 to 928MHz

The band 902 to 928MHz is allocated to ISM in ITU-R Region 2 only, which includes North America. It is generally used for relatively low data rate systems requiring wide area coverage such as long range cordless telephones and telemetry networks. Other regions, especially those which use the GSM mobile phone standard, have licensed services in this band which are incompatible with SRD systems.

The band 902 to 928MHz is also used by RFID as discussed in section 5.5.

The Australian Class Licence for Spread Spectrum Devices provides for 1W e.i.r.p. devices in the 915 to 928MHz band. This is sufficient bandwidth to accommodate many of the devices designed for the Region 2 market without modification.

Europe and many Asian countries have no allocations for low power devices in this band because of allocations for mobile systems such as GSM and TETRA which cannot share with WLANs.

The New Zealand GURL for SRDs permits devices up to 1W e.i.r.p. to operate in the band 921 to 929MHz. The adjacent band 915 to 921MHz is allocated to STLs which are not tolerant to sharing with low power devices. Telemetry and telecommand SRDs with a maximum e.i.r.p. of 3mW are permitted in the 915 to 921MHz band under the SRD GURL. The band below 915MHz is under management rights and used for a GSM mobile network.

Typical systems designed for the North American market use frequency hopping spread spectrum and occupy at least 12MHz. They are not easily adapted to the 8MHz between 921 to 929MHz available in New Zealand.

The allocations of the 902 to 928MHz band are summarised in the following table:

4.4 Conclusions for 902 to 928MHz

It is not possible to permit 1 Watt e.i.r.p. systems below 921MHz in New Zealand because of the protection required by existing Studio Transmitter Links (STL). It is acknowledged that this precludes the use of most spread spectrum devices designed for the Region 2 ISM band at 900MHz. The Ministry needs to identify whether future demand for this band is better served by preserving it for STL use or developing a migration plan towards use by SRD. One option is for the Ministry to freeze the use of the band 915 to 921MHz by Studio Transmitter Links until the relative benefits of these competing uses have been evaluated.

Proposal 4.a

The Ministry invites comment on the anticipated demand for the 915 to 921MHz band by Studio Transmitter Links and Short Range Devices.

In particular comment is invited on the proposal to freeze future licences for STL in this band.

4.5 Review of 2400 to 2483.5MHz

The band 2400 to 2500MHz is allocated internationally for ISM. It is used by a variety of ISM and communication devices including microwave ovens, cordless phones and wireless LANs.

The band 2400 to 2483.5MHz is also used by RFID (refer to section 5.6) and AV Senders (refer to section 8).

In the USA the band 2400 to 2483.5 is dominated by WLANs using the IEEE 802.11 standards. Both spread spectrum and digital modulation are allowed and the maximum radiated power with an omni directional antenna is 4 Watt e.i.r.p. provided the transmitter power into the antenna does not exceed 1W.

Point to point links are also permitted with directional antenna. The maximum transmitter input to the antenna reduces by 1dB for every 3dB increase in antenna gain above 6dBi. The maximum e.i.r.p. for point to point links is summarised in the following table:

In New Zealand a radiated power of 4W is permitted in the band 2400 to 2483.5MHz using spread spectrum or digital modulation.

A summary of the various allocations are provided in the following table:

4.6 Conclusions for 2400 to 2483.5MHz

The current New Zealand GURL for SRD appears to accommodate most equipment available for the 2400 to 2483.5MHz band. However there may be interest in permitting higher radiated power for point to point systems using gain antenna as permitted in US. These would be similar to those permitted at 5.8GHz under the Fixed Radio Link GURL. It is uncertain whether there is interest in introducing the same type of service in the 2.4GHz band which is already in high demand.

Proposal 4.b

The Ministry invites comment on the assessment of the 2.4GHz spectrum demand.

Of particular interest are indications of the demand for higher power point-to-point systems in this band.

4.7 Review of 3650 to 3700MHz

The United States FCC are considering the band 3650 to 3700MHz for service expansion of unlicensed fixed wireless access systems.7

This band requires co-ordination with fixed satellite services (FSS space-to-earth). The FCC are proposing interference mitigation into satellite services using DFS by monitoring the earth-to-satellite band. They also propose transmitter power control and possibly station identification in the transmissions.

In New Zealand this band is allocated to fixed services (P Band) where there are currently five licences. The band is adjacent to privately owned Management Rights which are being used for Fixed Wireless Access Services.

The band also falls within one of the bands being considered for 4th generation mobile systems.

A summary of the 3.7GHz band allocations is provided in the following table:

4.8 Conclusions for 3650 to 3700MHz

The Ministry will be watching the progress of this proposal for the 3650 to 3700MHz band and will evaluate the interference mitigation mechanisms in the New Zealand context once they have been defined.

Proposal 4.c

The Ministry invites comment on the implications of a GURL being issued for FWA systems in the band 3650 to 3700MHz. It is acknowledged that once the international position has been clarified there will need to be further consultation before the Ministry takes any action on this band

4.9 Overview of 5150 to 5875MHz

The 5150 to 5875MHz band is not a contiguous band available under a GURL. It is made up of a number of sub bands each with their own operational requirements. This band is seen as a natural migration point for wireless systems where the 2.4GHz band has become too congested. However it is also targeted by new FWA systems based on standards which are still under development.

The ITU-R Resolution 229 was passed at the recent WRC 2003 and provides a reference for the various sub-bands within 5150 to 5725MHz. This Resolution is reproduced in Appendix C of this paper. European, Asian and North American countries are in the process of adopting this resolution. The adjacent band 5725 to 5875MHz is allocated internationally to ISM.

Resolution 229 introduces Dynamic Frequency Selection (DFS) and Transmitter Power Control (TPC) as two technologies which enable this band to be shared with licensed services. In October 2003 IEEE released an amendment 5 to the standard 802.11h which specifies DFS and TPC and can be applied to the existing 802.11a WLAN standard. There does not appear to be any compliant product on the market at this time.

Considering each sub-band in detail:

4.9.1 Review of 5150 to 5250MHz

ITU-R Resolution 229 specifies 200mW e.i.r.p. and indoor use only. USA, Europe and Australian regulators are already compliant with these requirements. The band is shared with earth to space feeder links for non-geostationary systems in the mobile satellite service.

The New Zealand GURL for SRD specifies 250mW which exceeds the ITU-R level by 1dB.

4.9.2 Conclusions for 5150 to 5250MHz

To be compliant with ITU-R Resolution 229 the radiated power would need to be reduced from 250mW to 200mW in the band 5150 to 5250MHz. Also the indoor use restriction would need to remain.

Proposal 4.d

The Ministry invites comment on the implications of the proposed change in radiated power level from 250mW to 200mW in the 5150 to 5250MHz band.

4.9.3 Review of 5250 to 5350MHz

ITU-R Resolution 229 specifies 200mW and predominately indoor use. The band is shared with earth exploration satellite, radiolocation and space research services on a primary basis. Outdoor use allows for up to 1W e.i.r.p. but with limitations on the power radiated above the horizontal to protect satellite systems. DFS and TPC are required to protect licensed radiolocation systems.

USA complies with Resolution 229. Europe is compliant but also limits the e.i.r.p. to 200mW. In Australia the ACA are currently considering the responses to their recent discussion paper on the 5GHz band.8 It appears likely that they will move towards compliance with the ITU-R resolution.

An added consideration in Australia is the new ITU-R footnote 5.447E from WRC-03 which allocates the band 5250 to 5350 for Fixed Services on a co-primary basis in some Region 3 countries including Australia (but not New Zealand). The use of this band is intended for Fixed Wireless Access (FWA) systems. This appears to have been a strategic move at the WRC and there is little interest from the regulatory authority or the industry for implementing FWA in this band.

Several Asian countries are in the process of adopting this resolution where possible.

The current New Zealand allocation allows for 250mW e.i.r.p. with no requirement to be predominately indoors. The allocation would need changing to become compliant with resolution 229.

4.9.4 Conclusions for 5250 to 5350MHz

To be compliant with ITU-R Res. 229 it is necessary to increase the permitted radiated power from 250mW to 1 Watt in the band 5250 to 5350MHz with the conditions as detailed in Res.229, including restrictions to e.i.r.p. above the horizontal and the requirements for DFS and TPC.

Proposal 4.e

The Ministry invites comment on the proposal to permit the operation of wireless LANs in the band 5470 to 5725MHz.

4.9.5 Review of 5350 to 5470MHz

This band is allocated internationally to aeronautical radionavigation and is not able to be shared with short range devices.

4.9.6 Review of 5470 to 5725MHz

This band is allocated to maritime radionavigation and radiolocation. In particular meteorological radar is installed in many countries and interference mitigation is essential before the band can be shared with other services. ITU-R Resolution 229 allows 250mW transmitter power and 1W e.i.r.p. (using a 6dBi gain antenna) provided DFS and TPC are employed. USA and Europe have already adopted the Resolution 229 and Australia is likely to follow suit.

Asian countries have generally not yet adopted this aspect of Resolution 229.

The current New Zealand GURL for SRD permits 100mW services for radiolocation in this band.

4.9.7 Conclusions for 5470 to 5725MHz

To be compliant with ITU-R Res. 229 the Ministry is investigating the feasibility of allocating the band 5470 to 5725MHz to wireless LAN. This would include increasing the permitted radiated power from 100mW to 1 Watt and including the requirements for DFS and TPC, as detailed in Res.229. Discussions are currently underway with existing licence holders in this band.

Proposal 4.f

The Ministry invites comment on the implications of permitting operation of wireless LANs in the band 5470 to 5725MHz.

4.9.8 Review of 5725 to 5875MHz

This is a long established international ISM band. Most countries allow WLANs to operate in this band. USA, Australia and New Zealand allow 4W e.i.r.p. with some conditions. UK allow 2W and systems are subject to "light licensing" because of the need to co-ordinate with a number of licensed system.

Other Pacific rim countries generally permit WLAN operation in this band.

USA and New Zealand also permit fixed radio links to operate with up to 200W e.i.r.p. in the 5725 to 5825MHz band provided the transmitter output power is limited to 1W (that is an antenna with a gain up to 23dBi is permitted). This is covered by the GURL on Fixed Radio Links.9 Australia have released a discussion paper proposing that 200W links be individually licensed in rural areas on a no interference, no protection basis.

The band is also being evaluated for use by emerging FWA systems based on the IEEE 802.16 and European HIPERMAN standards. These standards are typically 1W point to multipoint systems which could feasibly share the band with existing WLAN systems.

The band 5850 to 5925MHz is also under consideration for Dedicated Short Range Communications (DSRC) devices used for exchanging high data rate transmissions between vehicles and between vehicle and roadside.

4.9.9 Conclusions for 5725 to 5875MHz

Considering that the current allocations in New Zealand in the band 5725 to 5875MHz are consistent with international standards the Ministry does not intend to make any changes at this time.

Proposal 4.g

The Ministry proposes to monitor the developments of new FWA and DSRC standards and will review the conditions of use for the band 5725 to 5875MHz band once these are finalised.

A summary of the 5GHz band allocations is provided in the following table:

3 Recommendation ITU-R SM.1538.1 - Technical and operating parameters and spectrum requirements for short-range radiocommunication devices.

4 Resolution ITU-R 229 (WRC03) - Use of the bands 5150 - 5250, 5250-5350MHz and 5470-5725MHz by the mobile service for the implementation of wireless access systems including radio local area networks. Refer to footnote 6 which has a copy of ITU-R RES 229 in the appendix.

5 IEEE Standard 802.16-2004 - WirelessMANTM Standard for Wireless Metropolitan Area Networks.

6 ETSI HIPERMAN, a European standard for fixed wireless access networks operating below 11GHz.

7 FCC 04-100 - Notice of Proposed Rule Making, 23 April 2004

8 ACA discussion paper Proposals for Spectrum Arrangements for RLANS and FWA Systems in the 5GHz Frequency Range post WRC-03

9 New Zealand Radiocommunications Regulations (General User Radio Licence for Fixed Radio Link Devices) Notice 2004.