US Patent 9271272 Communications system with multiple PDCCH with associated multiple DMRS patterns

A communication system is presented in which a base station is provided for communicating with a plurality of mobile communication devices in a cellular communication system. The base station operates one of more communication cells and communicates subframes, with each of the plurality of communication devices within the cell(s), each comprising the communication resources of a control region for communicating a control channel and the communication resources of a data region for communicating a respective data channel. The base station communicates a control channel having a first DMRS sequence in a control region of some subframes and a control channel having a second DMRS sequence in a control region of other subframes. The second control channel may be transmitted in a radio beam focussed spatially in a direction of a communication device. The first control channel may be transmitted omnidirectionally throughout the cell(s).