Light emitting diodes (LEDs), which likely emit thermal states, are easy to implement alternatives to the usually taken lasers when deployed at quantum transmitters of wireless quantum optical communications. However, using LEDs leads to increased bit error and block error ratios in the said wireless quantum optical communication concepts. These increases of the error ratios can be mitigated by applying sophisticated channel coding, e.g. polar coding, which has been included in the Fifth Generation New Radio (5 G/NR) standard. In addition, applying turbo equalization, proposed for classical communications in the 1990s, seems attractive when striving for improved robustness of wireless quantum optical communications. In this manuscript the recently emerged laser based polar coded wireless quantum optical communication concept with turbo equalization, which has been applied to multipath reception scenarios, will be extended to the case of LED based polar coded wireless quantum optical multipath communications. We will demonstrate the viability of the proposed concept with selected simulation results.
Light emitting diodes (LEDs), which likely emit thermal states, are easy to implement alternatives to the usually taken lasers when deployed at quantum transmitters of wireless quantum optical communications. However, using LEDs leads to increased bit error and block error ratios in the said wireless quantum optical communication concepts. These increases of the error ratios can be mitigated by applying sophisticated channel coding, e.g. polar coding, which has been included in the Fifth Generation New Radio (5 G/NR) standard. In addition, applying turbo equalization, proposed for classical communications in the 1990s, seems attractive when striving for improved robustness of wireless quantum optical communications. In this manuscript the recently emerged laser based polar coded wireless quantum optical communication concept with turbo equalization, which has been applied to multipath reception scenarios, will be extended to the case of LED based polar coded wireless quantum optical multipath communications. We will demonstrate the viability of the proposed concept with selected simulation results.
Wireless communication above 300GHz requires highly sophisticated analog circuit design due to severe frequency dependent ohmic losses. The complexity of such electronic hardware motivates exploring wireless quantum optical communication approaches even for the 6G “terahertz (THz) range” 300GHz,10THz. In this work, the classical radio frequency (RF)-based inner physical layer (PHY) transceiver blocks of channel coded wireless communication systems are replaced by wireless quantum optical transceiver blocks. Short range concepts employing LEDs as transmitters are particularly attractive, owing to their low implementation cost and practical simplicity. In contrast to laser based wireless quantum optical transmission over multipath channels, the quantum mechanical density operator ρ̲RX,[si,bi] and the transition probability γ(si,si+1) required by the quantum data detection must be revised accordingly. Furthermore, the novel interpretation introduced here, in which the extrinsic information is treated as a diversity branch rather than as an estimate of the a priori information, facilitates turbo equalization that still can accomodate varying a priori information. However, due to the limited uncoded transmission performance achievable with such systems, the incorporation of sophisticated channel coding schemes appears imperative. The authors therefore investigate the combination of sophisticated channel coding techniques, such as polar coding, with LED based wireless quantum optical transmission technologies. All numerical results assume a cryogenically cooled receiver front-end (approximately 10 K), yielding thermal noise levels. Operation at room temperature in the 6G THz range 300GHz,10THz would require an average number N¯α of thermal noise photon values of approximately 5 to 20, which is beyond the scope of this feasibility study. The results show that the proposed paradigm enables simple, robust, and practically viable wireless quantum optical communication systems with favorable transmission performance. Additional gains are achieved through iterative turbo equalization. The results also suggest that the proposed approach can pave the way toward robust and economically viable future communication solutions.
Wireless communication applications above 300 GHz need careful analog electronics design that takes into account the frequency-dependent nature of ohmic resistance at these frequencies. The cumbersome development of electronics brings quantum optical communication solutions for the sixth generation (6G) THz band located between 300 GHz and 10 THz into focus. In this manuscript, the authors propose to replace the classical radio frequency based inner physical layer transceiver blocks used in classical channel coded short range wireless communication systems by wireless quantum optical communication concepts. Besides discussing the resulting generic concept of the wireless quantum optical communications and illustrating optimum quantum data detection schemes, novel reduced state quantum data detection and novel Kohonen maps based quantum data detection, will be addressed. All the considered quantum data detection schemes provide soft outputs required for the lowest possible block error ratio (BLER) at the output of the channel decoding. Furthermore, a novel polar codes design approach determining the polar sequence by appropriately combining already available polar sequences tailored for low BLER is presented for the first time after illustrating the basics of polar codes. In addition, turbo equalization for wireless quantum optical communications using polar codes will be presented, for the first time explicitly stating the generation of soft information associated with the codebits and introducing a novel scheme for the computation of extrinsic soft outputs to be used in the turbo equalization iterations. New simulation results emphasize the viability of the theoretical concepts.
ABSTRACT Entanglement‐based quantum communication schemes, such as quantum teleportation, rely on classical communication links, which introduce significant transmission overhead and limit the achievable quantum advantage. To address this issue, this work investigates a non–entanglement‐based quantum communication concept. The proposed laser‐based physical layer (PHY) model accommodates a multipath quantum channel and receiver impairments, including intersymbol interference (ISI) caused by multipath propagation, thermal background noise, decoherence, the absence of phase coherence between transmitter and receiver, photon‐counting reception, dark counts and quantum efficiency. Because optimum full state sequence detection becomes increasingly complex with increasing channel memory, a reduced‐complexity trellis‐based, suboptimum yet practical sequence detection approach considering the ‐algorithm is applied. By extending this algorithm to generate soft outputs, a soft‐output ‐algorithm (SOMA) is obtained, enabling improved channel decoding. Two SOMA variants are introduced: a straightforward ‘post‐processing (PP)’‐SOMA and a more advanced ‘simple rule (SR)’‐SOMA. Results indicate that, particularly with SR‐SOMA, the proposed concept substantially reduces transmission overhead while ensuring reliable reception performance. Furthermore, the integration of classical channel coding, such as 3GPP 5G/new radio (5G/NR) polar codes, enhances overall system robustness. The proposed architecture can operate as a stand‐alone communication system without entanglement and may additionally convey the classical feed‐forward information required by entanglement‐based protocols.
Recent research has clarified that radio applications above 300 GHz require a laborious analog design that takes into account the frequency-dependent nature of ohmic resistance at these frequencies, bringing optical communication solutions, well suited for short range links in the sixth generation (6G) THz band located between 300 GHz and 10 THz, into focus. In particular, wireless quantum optical communication concepts are attractive, replacing the classical radio frequency based inner physical layer transceivers used in channel coded short range wireless communication systems. In particular, due to low environmental interaction of short range links, the prevailing coherence and interference ability when knowing and maintaining the carrier phase permits a beneficially robust wireless quantum optical transmission. In this manuscript, the viability of connecting the 5G/New Radio polar code and the proposed wireless quantum optical communication concept, which uses the optimum soft output quantum data detector for coherent reception with known carrier phase, is demonstrated by means of performance results.
In this communication, the authors illustrate the application of turbo codes in wireless quantum optical communications that suffer from intersymbol interference caused by multipath transmission. Setting out from the quantum mechanical system model, optimum quantum data detection will be briefly discussed. It will be illustrated that the optimum quantum data detection scheme uses a photon counter, measuring the radiation field and determining the number of photons in each detection time interval, followed by an optimum data detection algorithm known from classical communications, e.g. based on the Viterbi algorithm or the BCJR (Bahl-Cocke-Jelinek-Raviv) algorithm. Also, promising simulation results will be presented.
Research has shown that radio applications above300GHzrequire a very careful analog design that takes into account the frequency-dependent nature of ohmic resistance at these frequencies, bringing optical communication solutions for the sixth generation(6G)THzband located between 300 GHz and 10 THz, being well suited for short range links, into focus. The authors propose wireless quantum optical communications concepts replacing the classical radio frequency based inner physical layer transceivers used in classical channel coded short range wireless systems. Owing to low environmental interaction of such short range links, the coherence and interference ability when knowing and maintaining the carrier phase permits a beneficially robust transmission. Also, on the basis of today's wireless communication systems considering sophisticated channel codes such as the LTE turbo code and the WLAN LDPC code seems to be of greatest interest. Thus, besides illustrating the proposed wireless quantum optical communications concept, the optimum soft output quantum data detector for coherent reception with known carrier phase is discussed and both uncoded as well as novel channel coded bit error ratio performance results are presented.