An apparatus for establishing communication between a base station and different generation terminals includes a multi-protocol stack capable of processing user traffic received from different generation terminals. The apparatus also includes a common physical layer that receives user traffic from different generation terminals and identifies the generation of the terminal sending the user traffic. The user traffic is then processed and routed based on the terminal generation. Traffic can be prioritized across current and legacy terminal types based on a variety of factors.

A method performed on-board by a satellite for processing a signal received from a terminal during a current time interval, includes receiving, during the current time interval, a main signal containing a message from a terminal, each message having a priority level; sampling the main signal to obtain samples; storing the obtained samples into the satellite memory; first demodulating the messages corresponding to the current time interval contained in the samples stored in memory; when the satellite is in the range of a ground station, transmitting to the ground station the content of the memory. The first demodulating includes, for each message of the messages contained in the samples and by priority order: demodulating and decoding the message; forwarding, using direct link or inter-satellite-link, the demodulated message to a ground station; estimating the number of remaining non-demodulated messages in the samples stored in the memory.

Satellite communication methods and payloads are described. An imbalance in uplink and downlink availability may be mitigated through digitizing uplink spectrum, extracting guard band channels, and grouping the guard band channels to create a composite channel. The composite channel is converted to analog and RF up-converted, amplified, and multiplexed with other downlink analog channels before being transmitted to Earth. The guard bands may be from the same band of spectrum or different bands of spectrum, such as C band, Ka band, Ku band, etc. A satellite payload is described with dual output multiplexers having partially overlapping channels and a dual feed configuration. In one downlink implementation, unused regional band spectrum may be dynamically allocated to a spot beam. In one uplink implementation, regional band spectrum may be shared by a spot beam using spatial separation of the regional uplink location from the spot beam coverage area and digital cancellation techniques.

A wireless communication unit for compensating for Ionospheric group delay in a satellite communication system. The wireless communication unit comprises: a receiver configured to receive a multi-carrier signal from a satellite; and a processor coupled to the receiver. The processor is configured to: process the multi-carrier signal to produce a plurality of digital representations of individual carriers of the multi-carrier signal; estimate, from the plurality of digital representations of individual carriers of the multi-carrier signal, a Total Electron Content, TEC, value associated with a communication path between the satellite and the wireless communication unit through Earth's Ionosphere; and apply compensation for Ionospheric group delay subjected to the multi-carrier signal based on the determined TEC value.

An apparatus for establishing communication between a base station and different generation terminals includes a multi-protocol stack capable of processing user traffic received from different generation terminals. The apparatus also includes a common physical layer that receives user traffic from different generation terminals and identifies the generation of the terminal sending the user traffic. The user traffic is then processed and routed based on the terminal generation. Traffic can be prioritized across current and legacy terminal types based on a variety of factors.

Systems and methods relating to correction of a Doppler/frequency offset in a wireless communication system are disclosed. In some embodiments, a method of operation of a node comprises estimating a Doppler/frequency offset for a wireless device based on an uplink signal received from the wireless device and providing a frequency adjustment to the wireless device that corrects for the Doppler/frequency offset. In this manner, the Doppler/frequency offset for a wireless device is determined and corrected.

Operating a communication system comprises providing N transmitting antennas (TA) for transmitting symbol streams (SST) and K ground receivers (GR) which may be provided with symbol streams (SST) transmitted by transmitting antennas (TA). Transmitting antennas (TA) are located with a distance from Earth (E). Ground receivers (GR) are spatially separated from each other, wherein the constraint K>N applies. The method includes: simultaneously transmitting N symbol streams (SST) by N transmitting antennas (TA), receiving a linear combination of N simultaneously transmitted symbol streams (SST) by each ground receiver (GR), respectively, determining the respective linear combination for N transmitting antennas (TA) and each of the K ground receivers (GR), respectively, deciding on the basis of the determined linear combinations which of the K ground receivers (GR) is assigned to a respective common receiver group in order to be simultaneously and with the same frequency provided with symbol streams (SST).

A multiple-access transceiver handles communications with mobile stations in environments that exceed mobile station design assumptions without necessarily requiring modifications to the mobile stations. One such environment is in Earth orbit. The multiple-access transceiver is adapted to close communications with mobile stations while exceeding mobile station design assumptions, such as greater distance, greater relative motion and/or other conditions commonly found where functionality of a terrestrial transceiver is to be performed by an orbital transceiver. The orbital transceiver might include a data parser that parses a frame data structure, a signal timing module that adjusts timing based on orbit to terrestrial propagation delays, frequency shifters and a programmable radio capable of communicating from the Earth orbit that uses a multiple-access protocol such that the communication is compatible with, or appears to the terrestrial mobile station to be, communication between a terrestrial cellular base station and the terrestrial mobile station.

Signal precoding can include: determining a first antenna pattern gain for a beam directed from a first antenna feed on the satellite toward a first user terminal in a first cell and determining a second antenna pattern gain for a beam directed from a second antenna feed on the satellite toward a second user terminal in a second cell adjacent to the first cell; wherein the adjacent cells are partitioned into sectors; determining a first sector location of the first user terminal and a second sector location of the second user terminal; a precoder matrix circuit using the determined first and second antenna pattern gains to calculate a precoder matrix to reduce interference levels caused by the first signal at the second sector and by the second signal at the first sector; and the precoder matrix circuit applying the precoder matrix to the first and second signals.

This application discloses a NB-IoT-based communication method and an apparatus, to evolve a NB-IoT communication technology into an NTN. The method is as follows: A terminal device generates an uplink signal, including a superframe which includes a synchronization sequence located in first duration of the superframe and a data frame located in second duration which is after the first duration, the synchronization sequence successively includes a first sequence repeated Ni times and a second sequence repeated N2 times, the second sequence is obtained by multiplying the first sequence by ?1, a part of consecutive sequences of the synchronization sequence are used as a first synchronization reference sequence that is obtained based on the second sequence repeated N2 times and one or more first sequences that are sorted from back to front in the first sequence repeated N1 times. The terminal device sends the uplink signal to a network device.