3.4 Technical considerations for lot design

TDD and FDD technologies

55. As noted, a key technical issue is incompatibility between TDD and FDD technologies, and the need to provide for both within the auction process for 2.5 GHz (that is, to not preclude a particular use by the way the auction is set up).

Guardbands

56. Management of interference at boundaries between spectrum owners must be effected through planning and co-ordination between operators (using separation, antenna placement and polarisation and the like) so that licences can ultimately be certified and registered. However, such coordination can be materially assisted if a guard band is available to increase frequency separation. In such spectrum, the burden of coordination, possibly within certain limits, would be borne by the guard band owner. The guard band may still be usable by the respective owner depending upon the location of proposed use and the parameters of use in the adjacent spectrum. Any such use of a guard band would need to recognise that the spectrum was intended as a guard band and that future licences proposed by the owner of the adjacent spectrum would need to be accommodated by altering or cancelling licences in the guard band.
57. Most submissions on the 2.3 GHz auction advocated that the Ministry should provide for some guardband spectrum in the lot design, rather than leaving it up to management right holders to acquire sufficient bandwidth to manage interference issues. 
58. Options therefore include:

• provide for guardbands (owned by the Ministry not management rights holders) between lots.
• require management right holders to acquire sufficient spectrum to manage interference issues, including by using guardbands.
• design lots to include sufficient bandwidth to allow for interference management.

59. The Ministry’s preference is that:
    1. management right holders take responsibility for managing interference issues, and
    2. acquire sufficient spectrum to be able to do so.

This in turn requires that the Ministry, in lot design, make sufficient spectrum available to allow for adequate guardbands and interference management.