NZ allows greater use of TDD in 3.5 GHz band

New Zealand’s Radio Spectrum Management (RSM) agency recently consulted current management right holders and Crown licensees in the 3.5 GHz band on a proposal to permit greater use of time division duplex (TDD) equipment in the band.

Taking into account the feedback from this, RSM has decided to allow greater use of TDD equipment in the band.

When management rights and Crown spectrum licences within the 3.5 GHz band were allocated in the 2000s, they were designed to be used by frequency division duplex (FDD) equipment.

Since then, there has been a shift internationally towards the manufacture and use of time division duplex (TDD) equipment for broadband wireless access (BWA).

Nevertheless, while TDD equipment is currently more widely available than FDD, it is not clear whether this will be the case in the future. A number of overseas manufacturers have recently undertaken trials of FDD equipment for the 3.5 GHz band.

In October 2014, Radio Spectrum Management (RSM) sent letters to management right holders and those licensing spectrum from the Crown in the 3.5 GHz band.

The majority of responses to the letters supported a shift to enable greater use of TDD equipment in the band.

Some respondents expressed a preference to continue to use their FDD equipment for the remainder of its usable life.

During its further consultation with users in March 2015, RSM proposed that Crown licensees be allowed to use TDD equipment in the Crown management rights and that unused spectrum in the centre band gap be made available for the trial of TDD equipment.

The majority of respondents supported the essence of the proposal. A number of respondents suggested alterations to the proposal to lower the risk of interference.

Taking into account the feedback from the submissions, RSM has decided:

1. To make two 5 MHz channels in the frequency ranges of 3495-3500 MHz and 3500-3505 MHz available for TDD trials by existing Crown licensees and private management right holders. This will be done under the administrative radio licensing regime.

To reduce risk of interference, the frequencies 3490-3495 MHz and 3505-3510 MHz will not be open for TDD trial.

Licences will be issued with a maximum of 12 months’ duration. The rules for temporary licensing in these frequencies will be specified in a public document. The issuing of licences will be at the discretion of the chief executive of MBIE. These licences will only be issued to entities that do not already have sufficient spectrum to trial TDD.

2. To allow Crown licensees to use TDD equipment within their current licences. Crown licensees wanting to do this will need RSM to amend the conditions on their licences which favour FDD.

Licensees will need an ARE (Approved Radio Engineer) to initiate and certify the licence modification requests in the Register of Radio Frequencies. Requests to modify licence conditions will need to be technically compatible with other incumbent licences.

In TLAs where there are two Crown licensees, licensees will need to come to an agreement with the other spectrum licensee before approaching RSM.

Licences modified to allow TDD use will also have a new condition specifying that any TDD deployment must transmit at a bandwidth no greater than 5 MHz.