On HARQ Schemes in Satellite-Terrestrial Transmissions

Abstract

As an efficient supplement for terrestrial communications, e.g., fifth-generation communication networks, satellite communication has been proved as a promising choice to realize seamless coverage, due to its inherent superiority over common wireless communication systems, like large-scale coverage area and flexibility of deployment. In this paper, a satellite-terrestrial transmission (STT) system including a satellite transmitter (S) and a group of terrestrial receivers (D) is focused on. Considering the randomness of D and employing stochastic geometry, the outage performance and diversity gain of three hybrid automatic repeat request (HARQ) schemes, generalized slotted ALOHA (GSA), repetition time diversity (RTD) and general incremental redundancy (IR), are respectively studied. In detail, the exact closedform analytical expression for the outage probability (OP) is derived for the GSA scheme, while the approximated expression for the OP of RTD scheme is presented and a useful expression for the OP of IR scheme is derived. Furthermore, the diversity gains of the three considered HARQ schemes are respectively investigated in STT scenarios. Finally, some numerical results are provided to validate the proposed analysis models.

Power Allocation for Reliable and Energy-Efficient Optical LEO-to-Ground Downlinks with Hybrid ARQ Schemes

“…For the transmission, the intensity modulation with on-off-keying (OOK) is assumed, and direct detection is used for the reception. It is also hypothesized that a negative acknowledgment (NACK) or no acknowledgment at all to a particular frame transmission by the receiving terminal will initiate a series of retransmissions via an HARQ protocol [5][6][7][8]. The maximum number of HARQ rounds is predefined and equal to M. During these M rounds, the receiver either successfully decodes the message and responds with a positive acknowledgment (ACK) or fails to decode it, and the re-transmission stops.…”

“…In particular, hybrid ARQ (HARQ) combines error detection with error correction by adding redundancy bits to the transmitted frames, and if the message decoding fails, a series of retransmission rounds are performed [5][6][7][8]. Depending on whether the erroneous message is discarded or stored, the HARQ is categorized as Type I HARQ or soft combining HARQ, respectively [5][6][7][8].…”

“…In particular, hybrid ARQ (HARQ) combines error detection with error correction by adding redundancy bits to the transmitted frames, and if the message decoding fails, a series of retransmission rounds are performed [5][6][7][8]. Depending on whether the erroneous message is discarded or stored, the HARQ is categorized as Type I HARQ or soft combining HARQ, respectively [5][6][7][8]. The latter is performed in practice based on the following two methods: chase combining (CC), in which the transmitter sends identical copies of the corrupted frame on each round and the receiver employs maximal ratio combining, whereas in incremental redundancy (IR) the transmitter sends more parity bits on each round, increasing the successful decoding probability [5][6][7][8].…”

“…Depending on whether the erroneous message is discarded or stored, the HARQ is categorized as Type I HARQ or soft combining HARQ, respectively [5][6][7][8]. The latter is performed in practice based on the following two methods: chase combining (CC), in which the transmitter sends identical copies of the corrupted frame on each round and the receiver employs maximal ratio combining, whereas in incremental redundancy (IR) the transmitter sends more parity bits on each round, increasing the successful decoding probability [5][6][7][8]. The HARQ is superior when reliability and link adaptation are required due to the joint error detection and correction, while costwise it is potentially cheaper.…”

An Incentive Mechanism for Computation Offloading in Satellite-Terrestrial Internet of Vehicles

“…Third, resource allocations [10] and computation offloading transactions require low time delay or there is no necessity to conduct it. Therefore, we design costumed algorithms during different stages which guarantee system and computation efficiency [11]. Lastly, the battery capacity is still a limitation of supporting energy consumption [12].…”