Adapting reference signal density

A non-transitory computer-readable storage medium storing a computer program element comprising computer program code to, when loaded into a computer system and executed thereon, cause the computer to perform a method of operating a wireless communications network comprising a plurality of user terminals and a plurality of base stations, locations of the plurality of base stations being dynamically variable, wherein the plurality of base stations transmit signals comprising a plurality of data units containing reference signals for use in channel assessment by mobile stations receiving the transmissions, the method comprising:

• maintaininq position data in a network management system relating to relative positions of the plurality of base stations;
• selecting, by the network management system, a reference signal pattern density for one or more of the plurality of base stations in accordance with the position data, and selecting, by the network management system, from a predetermined set of distribution patterns of reference signals, a distribution pattern having the selected reference signal pattern density over the plurality of data units,
• the network management system causing each of the plurality of base stations to generate a signal configured according to a first protocol for transmission to one or more user terminals, the signal comprising reference signals arranged in the distribution pattern and the reference signal pattern density of the plurality of data units selected for that base station, and
• transmitting instructions from the network management system to one or more of the plurality of base stations modifying the selected reference signal pattern densities for the one or more base stations in response to changes in the maintained position data relating to the relative positions of the plurality of base stations.

A wireless communications system comprising:

• a plurality of base stations configured to transmit signals comprising a plurality of data units, locations of the plurality of base stations being dynamically variable, wherein the plurality of base stations have signal transmission means for transmitting signals comprising a plurality of data units containing reference signals for use in channel assessment by mobile stations receiving the transmissions, wherein each of the plurality of base station has means to generate a signal configured according to a first protocol for transmission to one or more user terminals, the generated signal comprising reference signals arranged in a distribution and a density of the plurality of data units selected for that base station;
• and
• a network management system comprising a density selection processing system for selecting a density for the data units in the transmissions of respective base stations and configured to:
• maintain position data relating to relative positions of the base stations,
• select, for one or more of the plurality of base stations, a distribution pattern from a predetermined set of distribution patterns of reference signals, having a respective pattern density selected in accordance with the position data,
• cause the one or more of the plurality of base stations to transmit a signal comprising reference signals arranged in the selected distribution and density of plurality of data units, and
• transmit instructions to one or more of the plurality of base stations to modify selected reference signal densities in response to changes in the maintained position data relating to the relative positions of the base stations, and transmitting instructions to the base stations from the network management system.