Wireless Communication System Design
Apparatus and methods are provided for low latency an ultra-low latency (ULL) communications. In novel aspect, short TTIs are configured for low latency communications. The UE configures one or more downlink short transmission time interval (sTTI) regions over a normal TTI region, decodes one or more low latency control channels, which indicates one or more sTTI regions for one or more UEs, and obtains one or more sTTI regions for the UE based on the decoded low latency control channels. In one embodiment, the location short TTI control channels is determined by detecting a short TTI control message at a beginning of a TTI and obtaining a duration of the short TTI in the detected short TTI control message. In one embodiment, the UE obtains one or more uplink resources, power control and CSI configurations based on corresponding downlink short TTI transmissions according to a mapping rule.
1 . A method comprising:
configuring one or more downlink short transmission time interval (sTTI) regions over a normal TTI region in a system bandwidth by a user equipment (UE) in a wireless network, wherein the resources in the sTTI regions have short TTI length;
decoding one or more low latency control channels and one or more normal latency control channels, wherein each low latency control channel indicates one or more sTTI regions for one or more UEs in the wireless network; and
obtaining one or more sTTI regions for the UE based on the decoded one or more low latency control channels and the one or more normal latency channels.
2 . The method of claim 1 , wherein locations of the normal TTI control channels and the short TTI control channels are preconfigured.
3 . The method of claim 1 , wherein the location short TTI control channels is determined by detecting a short TTI control message at a beginning of a TTI and obtaining a duration of the short TTI in the detected short TTI control message.
4 . The method of claim 1 , wherein the one or more short TTI regions are configured by a short TTI configuration comprising: configuration through a SIB message, configuration through a dedicated RRC configuration, configuration through a dynamic signaling, and a static configuration.
5 . The method of claim 4 , further comprising: activating the short TTI region configuration, wherein the one or more short TTI regions are configured upon successful activation.
6 . The method of claim 5 , wherein the activating of the short TTI region configuration involves receiving an activation signal via a normal latency control command.
7 . The method of claim 1 , further comprising:
obtaining one or more uplink resources based on corresponding downlink short TTI transmissions, wherein the one or more uplink resources are mapped to corresponding downlink short TTI transmissions according to a mapping rule.
8 . The method of claim 7 , wherein the mapping rule is to map an uplink resource transmission time based on the corresponding downlink short TTI transmission time and a predefined processing time.
9 . The method of claim 7 , wherein the mapping rule is to dynamically map an uplink resource based on corresponding regular TTI and one or more short TTIs.
10 . The method of claim 1 , further comprising:
mapping uplink resources in parallel to corresponding a downlink transmission, wherein the downlink transmission includes one or more short TTIs within a regular TTI; and
adjusting uplink transmission power based on based a TTI power priority rule, wherein the TTI power priority.
11 . The method of claim 10 , wherein the TTI power priority rule indicates a short TTI with the shortest TTI length has the highest priority, and a short TTI has higher priority than a normal TTI.
12 . The method of claim 1 , wherein a short PDSCH (sPDSCH) is demodulated based on CRS, and wherein Pa/Pb for downlink power control is configured with different value than a regular PDSCH.
13 . The method of claim 1 , wherein a transmission mode for a short PDSCH (sPDSCH) is configured differently from a regular PDSCH.
14 . The method of claim 1 , wherein a CSI feedback for a short PDSCH (sPDSCH) is configured differently from a regular PDSCH.
15 . A method comprising:
configuring one or more downlink short transmission time interval (sTTI) regions over a normal TTI region in a system bandwidth by a base station in a wireless network, wherein the resources in the sTTI regions have short TTI length;
encoding one or more low latency control channels and one or more normal latency control channels, wherein each low latency control channel indicates one or more sTTI regions for one or more UEs in the wireless network; and
transmitting radio resources, wherein the radio resources comprises one or more sTTI regions for one or more user equipment (UE).
16 . The method of claim 15 , wherein locations of the normal TTI control channels and the short TTI control channels are preconfigured.
17 . The method of claim 15 , wherein the location short TTI control channels is determined by detecting a short TTI control message at a beginning of a TTI and obtaining a duration of the short TTI in the detected short TTI control message.
18 . The method of claim 15 , wherein the one or more short TTI regions are configured by a short TTI configuration comprising: configuration through a SIB message, configuration through a dedicated RRC configuration, configuration through a dynamic signaling, and a static configuration.
19 . The method of claim 18 , further comprising: sending a short TTI activating signal via a normal latency control command, wherein the activating signal indicates short TTI regions being configured.
20 . The method of claim 15 , further comprising:
receiving one or more uplink resources based on corresponding downlink short TTI transmissions, wherein the one or more uplink resources are mapped to corresponding downlink short TTI transmissions according to a mapping rule.
22 . A user equipment (UE), comprising:
a radio frequency (RF) transceiver that transmits and receives radio signals in a wireless communication network;
a transmission time interval (TTI) configurator that configures one or more downlink short TTI (sTTI) regions over a normal TTI region in a system bandwidth in a wireless network, wherein the resources in the sTTI regions have short TTI length;
a decoder that decodes one or more low latency control channels and one or more normal latency control channels, wherein each low latency control channel indicates one or more sTTI regions for one or more UEs in the wireless network; and
a resource locator that obtains one or more sTTI regions for the UE based on the decoded one or more low latency control channels and the one or more normal latency channels.
23 . The UE of claim 22 , wherein locations of the normal TTI control channels and the short TTI control channels are preconfigured.
24 . The UE of claim 22 , wherein the location short TTI control channels is determined by detecting a short TTI control message at a beginning of a TTI and obtaining a duration of the short TTI in the detected short TTI control message.
25 . The UE of claim 22 , wherein the one or more short TTI regions are configured by a short TTI configuration comprising: configuration through a SIB message, configuration through a dedicated RRC configuration, configuration through a dynamic signaling, and a static configuration.
26 . The UE of claim 22 , further comprising:
an uplink encoder that obtains one or more uplink resources based on corresponding downlink short TTI transmissions, wherein the one or more uplink resources are mapped to corresponding downlink short TTI transmissions according to a mapping rule.