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Item type:Publication, Access status: without files , Multi-channel self-organized TDMA for future aeronautical mobile ad-hoc networks(IEEE, 2024-03-21); ; ; Modernizing communication systems is crucial for the future of aviation, and the <inline-formula><tex-math notation="LaTeX">$L$</tex-math></inline-formula>-dacs Digital Aeronautical Communications Systemin(LDACS) in Air-Ground (A/G) and Air-Air (A/A) modes is being developed European and American organizations to meet this need. In this study, we explore possible channel access schemes for aeronautical ad-hoc networks. We propose Multi-Channel Self-Organized TDMA (MCSOTDMA), a novel variant of randomized, reservation-based slottedALOHA for LDACS A/A. In particular, we prove that it can achieve an optimal delay by following the <inline-formula><tex-math notation="LaTeX">$\frac{1}{e}$</tex-math></inline-formula>-rule of traditional slotted ALOHA's throughput. This new variant allows users to distributively converge towards an optimal channel access strategy with no a-priori knowledge of their neighborhood. It scales to any number of users and always guarantees a freely chosen, average packet collision probability. We evaluate the performance on the busiest oceanic airspace, and compare it to medium access schemes used in maritime and other aeronautical networks. We demonstrate that arbitrary collision rates can be achieved at the cost of proportional packet delay, establish communication links with deterministic performance, and implement broadcast voice messaging among pilots. We provide access to the simulator and a protocol specification under open licenses, in line with the principles of open science.Publicationtype: Journal Article45 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Communication Analysis between an Airborne Mobile User and a Terrestrial Mobile NetworkMobile services like GSM and LTE are increasingly offered on board of long-haul flights. This is achieved by installing an onboard base station, namely a GSM BTS or an LTE eNodeB in the airplane. Additionally, the airplane is equipped with a network control unit (NCU) device which prevents onboard mobile users from attempting to connect to ground mobile networks and, therefore, affect or interfere with terrestrial communications. The objective of this paper is to evaluate the need of the network control unit. For that purpose, it is investigated if a mobile user in the airplane can establish a connection with an existing terrestrial GSM or LTE network without the presence of the network control unit and the onboard base station. Only a few studies exist which investigate this connection. The analysis done in this paper takes into consideration physical and high layer requirements of both GSM and LTE networks.Publicationtype: Journal Article185 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , A Low-Complexity Interference-Aware Sphere Detector for Imperfect Channel Estimates(2016-07); ; In practical applications, an imperfect channel estimate over a noisy channel is inevitable. This paper investigates an interference-aware receiver in which colored-estimation-noise-based maximum-likelihood (CEN-ML) detection is employed to mitigate the impact of imperfect channel estimates. It is shown that the CEN-ML detection, which treats the channel estimation errors as colored noise, has superior performance and is robust to imperfect channel estimation. However, a CEN-ML interference-aware detector usually requires computational efforts that are too complex for multiple-input-multiple-output (MIMO) interference-limited systems. To reduce the complexity, this paper proposes new methods for both the preprocessing and tree-search stages of an interference-aware sphere detector (SD). First, a channel extended matrix is constructed using the information from channel estimation errors in a preprocessing stage. The channel extension model can reduce the complexity without performance loss. Second, two tree pruning (TP) criteria are developed in a tree-search stage to make the implementation of the CEN-ML SD feasible. The first criterion is based on a lower bound of the CEN-ML metric and can achieve the same result as the optimal brute-force method. The second criterion is derived from an approximated metric and can further reduce the complexity with small performance loss. Simulation results for typical Third-Generation Partnership Project Long-Term Evolution (LTE)/LTE-Advanced scenarios show that the new methods provide the ability to deal with the channel estimation errors and to achieve a better tradeoff between complexity and performance (e.g., in terms of throughput or error rate) in interference-limited scenarios. The proposed low-complexity CEN-ML SD can have a gain of more than 10 dB than the other investigated detection for 16-ary quadrature amplitude modulation (QAM) or 64-QAM at a target coded block error rate (BLER) of 10-2.Publicationtype: Journal Article134