MIMO Channel Dimension Estimation in Interference Channels with Antenna Disparity

While obtaining the channel state information (CSI) required to perform Interference Alignment (IA) in a centralised MIMO network is a challenge, this is compounded in unplanned wireless networks that may be decentralised - not to mention composed of devices with varying degrees of complexity and capability. This is of particular interest to heterogeneous networks and the Internet of Things (IoT). The disparity in antenna number caused by this variation in capability can be taken advantage of, increasing the sum rate of the network providing the users are aware of the capabilities of their neighbours. This paper presents a method for estimating with a high degree of certainty the number of antennas each user possesses, endowing the receiver with the vital CSI required before channel equalisation or estimation can take place. The method is correlation based and so is not restricted to full rank channels where the receiving device has an equal or greater number of antennas than the transmitter. This permits the use of the method in situations where the rank of the channel is restricted, either by design or by nature (e.g. 'keyhole' channels).