Method of control channel monitoring for reduced latency operation

1. A method comprising:

receiving, by a user equipment, a first indication indicating a plurality of physical resource block sets;

receiving a first control message in a beginning portion of a subframe, the first control message including information that indicates at least one selected physical resource block set from the plurality of physical resource block sets containing a second control message that is associated with a shortened transmission time interval;

determining, from the first control message, the at least one selected physical resource block set from the plurality of physical resource block sets; and

monitoring the second control message in the at least one selected physical resource block set of the shortened transmission time interval, wherein the duration of the shortened transmission time interval is smaller than the duration of the subframe.

2. The method of claim 1 , further comprising decoding a downlink data channel in the shortened transmission time interval based on the second control message.

3. The method of claim 1 , wherein the shortened transmission time interval belongs to the subframe.

4. The method of claim 1 , further comprising:

determining at least one default physical resource block set from the plurality of the physical resource block sets; and

monitoring the second control message in the shortened transmission time interval and in the at least one default physical resource block set in response to failing to receive the first control message.

5. The method of claim 1 wherein the plurality of physical resource block sets comprises a first physical resource block set and a second physical resource block set, the first physical resource block set having at least one different characteristic than the second physical resource block set from among: (i) spanning a different number of resource blocks than the second physical resource block set; (ii) utilizing a different number of decoding candidates than the second physical resource block set; (iii) utilizing a different number and value of aggregation levels than the second physical resource block set; and (iv) having a different location of resource blocks than the second physical resource block set.

6. The method of claim 1 , wherein the first control message includes an indication of a number of control channel decoding candidates to monitor for the second control message, the method further comprising determining, from the first control message, the number of control channel decoding candidates to monitor for the second control message.

7. The method of claim 1 further comprising:

determining a first control information based on the first control message; and

determining, based on the first control information, decoding candidates to be monitored to identify a second control information, the second control information containing scheduling assignment information related to data transmissions of the subframe length transmission time intervals in one or more of the current subframe and a subframe other than the current subframe.

8. The method of claim 1 , wherein:

the shortened transmission time interval is a first shortened time interval; and

the method further comprises:

monitoring the second control message using a first configuration; and

monitoring a third control message in the at least one selected physical resource block set of a second shortened transmission time interval using a second configuration;

wherein the second configuration has at least one of: (i) a different number of decoding candidates than the first configuration; (ii) a different aggregation level of the decoding candidates than the first configuration; and (iii) a different set of resource blocks than the first configuration.

9. The method of claim 8 , further comprising:

identifying any common reference signals that are transmitted in the first shortened transmission time interval;

identifying any common reference signals that are transmitted in the second shortened time interval; and

associating the corresponding one of the first and second configurations based on a presence or absence of common reference signals in the first and second shortened transmission time interval.

10. The method of claim 1 , further comprising:

receiving control signaling indicating at least one of: (i) a first user equipment-specific search space corresponding to the subframe and at a first aggregation level for a serving cell; and (ii) a second user equipment-specific search space corresponding to the shortened transmission time interval and at a second aggregation level for the serving cell; and

determining, based upon the received control signaling, (a) a first number of control decoding candidates for the first user equipment-specific search space and (b) a second number of control decoding candidates for the second user equipment-specific search.

11. The method of claim 10 , further comprising:

receiving in the control signaling an indication of one of the first and second user-specific search space; and

determining another one of the first and second user-specific search spaces based on at least one of: (i) the indication of the one of the first and second user-specific search space; (ii) a number of carriers configured for downlink data transmissions using transmission time intervals of the subframe length; and (iii) a number of carriers configured for downlink data transmissions using transmission time intervals of the first shortened transmission time interval length.

12. A user equipment comprising:

a transceiver;

a signal processing unit coupled to the transceiver and that is configured to receive a subframe comprising a plurality of time-frequency resources; and

a processor in communication with the signal processing unit and which:

receives a first indication from a node in a network indicating a plurality of physical resource block sets;

receives control signaling from the node, the control signaling comprising a first control message including information that indicates at least one selected physical resource block set from the plurality of physical resource block sets containing a second control message that is associated with a shortened transmission time interval;

determines, from the control signaling, first control information that indicates the at least one selected physical resource block set from the plurality of physical resource block sets that contains the second control message associated with the shortened transmission time interval; and

monitors the at least one selected physical resource block set to identify the second control message.

13. The user equipment of claim 12 , wherein the processor determines a first subset of decoding candidates used in a first transmit time interval of the subframe and a second subset of decoding candidates used in a second transmission time interval of the subframe, wherein the first subset is exclusive of the second subset and the second transmission time interval comprises the shortened transmission time interval and the first transmission time interval comprises two or more shortened transmission time intervals.

14. The user equipment of claim 13 , wherein the processor determines a respective first and second configuration of each transmission time interval of the two or more shortened transmission time intervals of the first transmission time interval, the first and second configurations each comprising at least one of: (i) a number of decoding candidates; and (ii) an aggregation level of the decoding candidates.

15. The user equipment of claim 14 , wherein:

a first subset of the two or more shortened transmission time intervals of the first transmission time interval are of the first configuration;

a second subset of the two or more shortened transmission time intervals of the first transmission time interval are of the second configuration;

the first subset is exclusive of the second subset; and

the first configuration is different from the second configuration.

16. The user equipment of claim 15 , wherein the processor:

determines whether common reference signals are transmitted in each one of the two or more shortened transmission time intervals of the first transmission time interval;

in response to determining that common reference signals are transmitted in a particular shortened transmission time interval, determines that the first configuration applies to the particular shortened transmission time interval; and

in response to determining that common reference signals are not transmitted in the particular shortened transmission time interval, determines that second configuration applies to the particular shortened transmission time interval.

17. The user equipment of claim 12 , wherein the processor determines that the first control information indicates a time division duplex configuration comprising more than one uplink/downlink switching points.

18. The user equipment of claim 12 , wherein the processor:

receives, via a higher layer of the network, control signaling of an indication of at least one of: (i) a first user equipment-specific search space corresponding to a first transmission time interval length and at a first aggregation level for a serving cell; and (ii) a second user equipment-specific search space corresponding to a second transmission time interval length and at a second aggregation level for the serving cell; and

determines (a) a first number of control decoding candidates for the first user equipment-specific search space and (b) a second number of control decoding candidates for the second user equipment-specific search space based upon the received control signaling, wherein the first transmission time interval length differs from the second transmission time interval length.

19. The user equipment of claim 12 , wherein the processor:

receives, in the control signaling, an indication of one of a first and second user equipment-specific search space; and

determines another one of the first and second user equipment-specific search spaces based on at least one of: (i) the indication of the one of the first and second user-specific search space; (ii) a number of carriers configured for operation with a length of the first transmission time interval; and (iii) a number of carriers configured for operation with a length of the second transmission time interval.

20. A method comprising:

transmitting, by a node, a first indication to a user equipment in a network indicating a plurality of physical resource block sets;

transmitting control signals to the user equipment, wherein the control signals contain a first control information that indicates at least one selected physical resource block set from the plurality of physical resource block sets that contains a second control information associated with a shortened transmission time interval; and

transmitting the at least one selected physical resource block set to identify the second control information.

21. The method of claim 20 , further comprising assigning a first subset of decoding candidates used in a first transmit time interval of the subframe and a second subset of decoding candidates used in a second transmission time interval of the subframe, wherein the first subset is exclusive of the second subset and the second transmission time interval comprises the shortened transmission time interval and the first transmission time interval comprises two or more shortened transmission time intervals.

22. The method of claim 21 , further comprising assigning a respective first and second configuration of each transmission time interval of the two or more shortened transmission time intervals of the first transmission time interval, the first and second configurations each comprising at least one of: (i) a number of decoding candidates; and (ii) an aggregation level of the decoding candidates.

23. The method of claim 22 , wherein:

a first subset of the two or more shortened transmission time intervals of the first transmission time interval are of the first configuration;

a second subset of the two or more shortened transmission time intervals of the first transmission time interval are of the second configuration;

the first subset is exclusive of the second subset; and

the first configuration is different from the second configuration.

24. The method of claim 23 , further comprising:

determining whether to transmit common reference signals in each one of the two or more shortened transmission time intervals of the first transmission time interval;

in response to determining that common reference signals are to be transmitted in a particular shortened transmission time interval, assigning the first configuration to the particular shortened transmission time interval; and

in response to determining that common reference signals are not to be transmitted in the particular shortened transmission time interval, assigning the second configuration to the particular shortened transmission time interval.

25. The method of claim 20 , further comprising indicating a time division duplex configuration that comprises more than one uplink/downlink switching points in the first control information.

26. The method of claim 20 , further comprising:

transmitting, via a higher layer of the network, control signaling of an indication of at least one of: (i) a first user equipment-specific search space corresponding to a first transmission time interval length and at a first aggregation level for a serving cell; and (ii) a second user equipment-specific search space corresponding to a second transmission time interval length and at a second aggregation level for the serving cell; and

determining (a) a first number of control decoding candidates for the first user equipment-specific search space and (b) a second number of control decoding candidates for the second user equipment-specific search space based upon the received control signaling, wherein the first transmission time interval length differs from the second transmission time interval length.

27. The method of claim 20 , further comprising transmitting, in the control signaling, an indication of one of a first and second user equipment-specific search space, enabling the user equipment to determine another one of the first and second user equipment-specific search spaces based on at least one of: (i) the indication of the one of the first and second user-specific search space; (ii) a number of carriers configured for operation with a length of the first transmission time interval; and (iii) a number of carriers configured for operation with a length of the second transmission time interval.