Relay control channel search space configuration

An apparatus, comprising:

• at least one memory including computer program code;
• and
• at least one processor,
• wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to
• hybrid multiplex, with time division multiplexing and frequency division multiplexing, a relay-physical downlink control channel and relay-physical downlink shared channel of a backhaul link for a relay node as a hybrid multiplexed set of symbols, wherein the relay-physical downlink control channel comprises a searching space with parameters semi-statically configured to be searched by the relay node;
• and
• transmit the hybrid multiplexed set of symbols to the relay node,
• wherein the at least one memory and the computer program code are also configured to, with the at least one processor, cause the apparatus at least to define the relay-physical downlink control channel searching space by a set of parameters including at least a physical resource block candidate set, a rank for the relay-physical downlink control channel, and control channel element aggregation level, and
• wherein the at least one memory and the computer program code are also configured to, with the at least one processor, cause the apparatus at least to semi-statically configure the rank for the relay-physical downlink control channel or to link the rank to another parameter selected from the physical resource block candidate set or the control channel element aggregation level, and
• wherein the rank for the relay-physical downlink control channel or a rank for the relay-physical downlink shared channel has been set a limit for the relay node.

A method, comprising:

• receiving a hybrid multiplexed set of symbols at a relay node;
• and
• hybrid de-multiplexing, with time division de-multiplexing and frequency division de-multiplexing, a relay-physical downlink control channel and relay-physical downlink shared channel of a backhaul link for the relay node as a hybrid de-multiplexed set of symbols,
• wherein the hybrid de-multiplexing comprises searching the relay-physical downlink control channel with a searching space with parameters semi-statically configured to be searched by the relay,
• wherein the hybrid de-multiplexing comprises searching the relay-physical downlink control channel searching space using a set of parameters including at least a physical resource block candidate set, a rank for the relay-physical downlink control channel, and control channel element aggregation level,
• wherein receiving the hybrid multiplexed set comprises receiving the hybrid multiplexed set having the rank for the relay-physical downlink control channel semi-statically configured or having the rank linked to another parameter selected from the physical resource block candidate set or the control channel element aggregation level, and
• wherein the rank for the relay-physical downlink control channel or a rank for the relay-physical downlink shared channel has been set a limit for the relay node.

An apparatus, comprising:

• at least one memory including computer program code;
• and
• at least one processor,
• wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to
• receive a hybrid multiplexed set of symbols at a relay node;
• and
• hybrid de-multiplex, with time division de-multiplexing and frequency division de-multiplexing, a relay-physical downlink control channel and relay-physical downlink shared channel of a backhaul link for the relay node as a hybrid de-multiplexed set of symbols,
• wherein hybrid de-multiplexing comprises searching the relay-physical downlink control channel with a searching space with parameters semi-statically configured to be searched by the relay node,
• wherein the at least one memory and the computer program code are also configured to, with the at least one processor, cause the apparatus at least to search the relay-physical downlink control channel searching space using a set of parameters including at least a physical resource block candidate set, a rank for the relay-physical downlink control channel, and control channel element aggregation level,
• wherein the at least one memory and the computer program code are also configured to, with the at least one processor, cause the apparatus at least to receive the hybrid multiplexed set having the rank for the relay-physical downlink control channel semi-statically configured or having the rank linked to another parameter selected from the physical resource block candidate set or the control channel element aggregation level, and
• wherein the rank for the relay-physical downlink control channel or a rank for the relay-physical downlink shared channel has been set a limit for the relay node.