Approaches for high speed global packet data services for LEO/MEO satellite systems
A satellite system comprises LEO satellites and MEO satellites, and a control plane protocol architecture. The PHY, MAC, MAC/RLC and RRC layers are optimized for satellite environment. When the satellites are not processing satellites, eNB functions are implemented in a satellite gateway, and, when the satellites are processing satellites, protocol architecture in the control plane differ from LTE, as follows: PHY layer is moved to the communicating LEO/MEO satellite on the user link, MAC/RLC, RRC and PDCP are be located in satellite or gateway depending on satellite complexity, and the need to have mesh connectivity between UTs. When the RRC is implemented in the satellite, the RRC is divided into RRC-Lower and RRC-Upper layers. The RRC-L is satellite-based, and handles UT handover. The RRC-U is eNB-based, and handles resource management functions. The RRC-U communicates with the PDCP layer in the eNB to configure security, header and data compression.
1. A satellite communications system comprising:
one or more low earth orbit (LEO) processing satellites;
one or more medium earth orbit (MEO) processing satellites;
one or more satellite gateways (SGWs), each including a respective eNodeB;
a plurality of user terminals (UTs);
a control plane protocol architecture comprising physical (PHY), media access control (MAC), MAC radio link control (MAC/RLC) and radio resource control (RRC) layers that are optimized for a satellite environment, and
wherein, with regard to control plane communications between a one of the UTs and a one of the LEO processing satellites or MEO processing satellites, which is the communicating LEO/MEO satellite, and between the communicating LEO/MEO satellite and a one of the SGWs, which is the communicating SGW,
the PHY layer is provided by a user-link of the communicating LEO/MEO satellite,
the MAC/RLC and RRC layers, and a packet data control plane (PDCP) layer, are implemented in the communicating LEO/MEO satellite when the system facilitates mesh communications between the one UT and one or more other of the UTs, and implemented in the communicating SGW when the system does not facilitate mesh communications between the one UT and one or more other of the UTs, and
when the RRC is implemented in the communicating LEO/MEO satellite, the RRC is divided into RRC-Lower (RRC-L) and RRC-Upper (RRC-U) layers, wherein the RRC-L is implemented in the communicating LEO/MEO satellite and is responsible for handover signaling with the one UT, and the RRC-U is implemented in the eNodeB of the communicating SGW and is responsible for resource management functions including admission control, and wherein the RRC-U communicates with the PDCP layer in the eNodeB of the communicating SGW to configure security, header compression and data compression schemes, and
wherein, with regard to user plane communications between the one UT and the communicating LEO/MEO satellite, and between the communicating LEO/MEO satellite and a destination server via the communicating SGW,
returnlink physical and logical channels include a returnlink packet data channel (PDCH) comprising a returnlink transport packet data traffic channel (PDTCH) logical channel and uplink control messages, and include a transport random access channel (transport RACH), and
forwardlink physical and logical channels include a forwardlink PDCH comprising a forwardlink PDTCH logical channel and downlink control messages, and include a forwardlink packet control channel (PCCH) comprising a broadcast channel, a paging channel, an access grant channel and a packet data control channel (PDCCH).