paper_authors: Mingjun Ying, Dipankar Shakya, Hitesh Poddar, Theodore S. Rappaport
for: This paper aims to improve the power efficiency of cascaded communication systems by developing a new metric called the Waste Factor ($W$).
methods: The authors use a mathematical framework to evaluate power efficiency in cascaded communication systems, by accounting for power wasted in individual components along a cascade. They also use the consumption efficiency factor (CEF) to evaluate the effects of insertion loss and deployment density on power efficiency.
results: The authors show that the Waste Factor is a unifying metric for defining wasted power in a cascade, and that it can be used to compare power efficiency between data centers and their components. They also observe that the CEF is markedly sensitive to insertion loss changes, particularly in uplink transmissions, and that energy efficiency improves at 142 GHz compared to 28 GHz as UE and BS numbers increase.Here’s the Chinese translation of the three points:
results: 作者们显示了 $W$ 是积离系统中定义浪费能量的统一指标，并且可以用来比较积离系统和其组件的能效性。他们还发现 CEF 受插入损失变化的影响非常大，特别是在上行传输中，而且能效性在142 GHz比28 GHz提高为 UE 和 BS 数量增加。Abstract
In this paper, we expand upon a new metric called the Waste Factor ($W$), a mathematical framework used to evaluate power efficiency in cascaded communication systems, by accounting for power wasted in individual components along a cascade. We show that the derivation of the Waste Factor, a unifying metric for defining wasted power along the signal path of any cascade, is similar to the mathematical approach used by H. Friis in 1944 to develop the Noise Factor ($F$), which has since served as a unifying metric for quantifying additive noise power in a cascade. Furthermore, the mathematical formulation of $W$ can be utilized in artificial intelligence (AI) and machine learning (ML) design and control for enhanced power efficiency. We consider the power usage effectiveness (PUE), which is a widely used energy efficiency metric for data centers, to evaluate $W$ for the data center as a whole. The use of $W$ allows easy comparison of power efficiency between data centers and their components. Our study further explores how insertion loss of components in a cascaded communication system influences $W$ at 28 GHz and 142 GHz along with the data rate performance, evaluated using the consumption efficiency factor (CEF). We observe CEF's marked sensitivity, particularly to phase shifter insertion loss changes. Notably, CEF variations are more prominent in uplink transmissions, whereas downlink transmissions offer relative CEF stability. Our exploration also covers the effects of varying User Equipment (UE) and Base Station (BS) deployment density on CEF in cellular networks. This work underscores the enhanced energy efficiency at 142 GHz, compared to 28 GHz, as UE and BS numbers escalate.
摘要
在本文中，我们扩展了一个新的度量 called Waste Factor ($W$), 用于评估级联通信系统中的能效性，通过对各个组件的能量损耗进行考虑。我们表明了度量Waste Factor的 derivation， 是级联通信系统中能效性度量的一个统一metric，类似于1944年Friis提出的Noise Factor ($F$)，该度量在级联通信系统中 quantifying 添加的噪声功率。此外，度量W的数学表述可以在人工智能（AI）和机器学习（ML）设计和控制中使用，以提高能效性。我们使用数据中心的能效性指标（PUE）来评估W，以便对数据中心和其组件进行简单的能效性比较。我们的研究还探讨了级联通信系统中组件插入损耗对W的影响，以及数据率性能，通过消耗效应因子（CEF）的变化来评估。我们发现CEF在28GHz和142GHz之间具有明显的敏感度，特别是在相位调制器插入损耗变化时。此外，我们还发现在无线电网络中 UE 和 BS 的分布密度变化对CEF的影响。这种研究表明了142GHz的能效性比28GHz更高，当 UE 和 BS 数量增加时。
A Sub-Terahertz Sliding Correlator Channel Sounder with Absolute Timing using Precision Time Protocol over Wi-Fi
paper_authors: Dipankar Shakya, Hitesh Poddar, Theodore S. Rappaport for:This paper aims to achieve sub-nanosecond timing accuracy for multipath component (MPC) propagation delays in power delay profiles (PDPs) for 5G and 6G communications at mmWave and sub-THz frequencies.methods:The proposed solution utilizes precision time protocol (PTP) and periodic drift correction to achieve absolute timing for MPCs in PDPs. The solution involves synchronizing the transmitter (TX) and receiver (RX) clocks using two RaspberryPi computers and a dedicated Wi-Fi link, and applying a periodic drift correction algorithm to eliminate PDP sample drift.results:The proposed solution achieves sub-nanosecond timing accuracy for MPC delays, reducing PDP sample drift to 150 samples/hour compared to several thousand samples/hour without synchronization. The solution shows promise in myriad applications, including precise position location and distributed systems that require sub-nanosecond timing accuracy and synchronization among components.Here is the information in Simplified Chinese text:for:这篇论文目标是在5G和6G通信中的mmWave和sub-THz频谱中实现多吉比特数据速率的 multipath component（MPC）延迟。methods:提议的解决方案利用精度时间协议（PTP）和周期偏移修正来实现MPC在电力延迟profile（PDP）中的绝对时间。解决方案使用两个RaspberryPi计算机和专门的Wi-Fi链接来实现TX和RX Rubidium时钟的同步，并应用周期偏移修正算法来消除PDP样本偏移。results:提议的解决方案实现了MPC延迟的sub-nanosecond精度，将PDP样本偏移降低至150个样本/小时，比不同的时钟同步方法而言有所下降。该解决方案在多种应用中展示了承诺，包括精确的位置定位和分布式系统，它们需要sub-nanosecond精度和同步。Abstract
Radio channels at mmWave and sub-THz frequencies for 5G and 6G communications offer large channel bandwidths (hundreds of MHz to several GHz) to achieve multi-Gbps data rates. Accurate modeling of the radio channel for these wide bandwidths requires capturing the absolute timing of multipath component (MPC) propagation delays with sub-nanosecond accuracy. Achieving such timing accuracy is challenging due to clock drift in untethered transmitter (TX) and receiver (RX) clocks used in time-domain channel sounders, yet will become vital in many future 6G applications. This paper proposes a novel solution utilizing precision time protocol (PTP) and periodic drift correction to achieve absolute timing for MPCs in power delay profiles (PDPs) --captured as discrete samples using sliding correlation channel sounders. Two RaspberryPi computers are programmed to implement PTP over a dedicated Wi-Fi link and synchronize the TX and RX Rubidium clocks continuously every second. This synchronization minimizes clock drift, reducing PDP sample drift to 150 samples/hour, compared to several thousand samples/hour without synchronization. Additionally, a periodic drift correction algorithm is applied to eliminate PDP sample drift and achieve sub-nanosecond timing accuracy for MPC delays. The achieved synchronicity eliminates the need for tedious and sometimes inaccurate ray tracing to synthesize omnidirectional PDPs from directional measurements. The presented solution shows promise in myriad applications, including precise position location and distributed systems that require sub-nanosecond timing accuracy and synchronization among components.
摘要
radio频道在mmWave和sub-THz频率上为5G和6G通信提供大量频带宽（百万Hz到几亿Hz）以实现多Gbps的数据速率。 precisely modeling radio频道需要 capture multipath component（MPC）延迟的绝对时间准确性（sub-纳秒级）。 Achieving such timing accuracy is challenging due to clock drift in untethered transmitter（TX）和receiver（RX）clocks used in time-domain channel sounders, yet will become vital in many future 6G applications。 This paper proposes a novel solution utilizing precision time protocol（PTP）and periodic drift correction to achieve absolute timing for MPCs in power delay profiles（PDPs）—captured as discrete samples using sliding correlation channel sounders。 Two RaspberryPi computers are programmed to implement PTP over a dedicated Wi-Fi link and synchronize the TX and RX Rubidium clocks continuously every second。 This synchronization minimizes clock drift, reducing PDP sample drift to 150 samples/hour, compared to several thousand samples/hour without synchronization。 Additionally, a periodic drift correction algorithm is applied to eliminate PDP sample drift and achieve sub-nanosecond timing accuracy for MPC delays。 The achieved synchronicity eliminates the need for tedious and sometimes inaccurate ray tracing to synthesize omnidirectional PDPs from directional measurements。 The presented solution shows promise in myriad applications, including precise position location and distributed systems that require sub-nanosecond timing accuracy and synchronization among components。
Robust Joint Active-Passive Beamforming Design for IRS-Assisted ISAC Systems
paper_authors: Mahmoud AlaaEldin, Emad Alsusa, Karim G. Seddik, Christos Masouros, Iman Valiulahi for: 这个研究旨在探讨 интеelligent reflective surfaces（IRS）与integrated sensing and communication（ISAC）系统之间的integraion，以改善未来无线网络中的spectrum congestion问题。methods: 这个研究使用了低复杂性和高效的共同优化算法，将BS的传发矩阵和IRS的反射矩阵共同优化，以最小化传发信号和欲要的射频范围之间的Frobenius距离。results: 研究结果显示，在不同的环境下，IRS-ISAC系统可以实现更好的传输和探测性能，并且可以适应不同的通信用户和射频范围。此外，这个研究还提出了一个对于IRS频率不确定性的强化 beamforming优化算法，可以对于实际系统中的频率不确定性进行适应。Abstract
The idea of Integrated Sensing and Communication (ISAC) offers a promising solution to the problem of spectrum congestion in future wireless networks. This paper studies the integration of intelligent reflective surfaces (IRS) with ISAC systems to improve the performance of radar and communication services. Specifically, an IRS-assisted ISAC system is investigated where a multi-antenna base station (BS) performs multi-target detection and multi-user communication. A low complexity and efficient joint optimization of transmit beamforming at the BS and reflective beamforming at the IRS is proposed. This is done by jointly optimizing the BS beamformers and IRS reflection coefficients to minimize the Frobenius distance between the covariance matrices of the transmitted signal and the desired radar beam pattern. This optimization aims to satisfy the signal-to-interference-and-noise ratio (SINR) constraints of the communication users, the total transmit power limit at the BS, and the unit modulus constraints of the IRS reflection coefficients. To address the resulting complex non-convex optimization problem, an efficient alternating optimization (AO) algorithm combining fractional programming (FP), semi-definite programming (SDP), and second order cone programming (SOCP) methods is proposed. Furthermore, we propose robust beamforming optimization for IRS-ISAC systems by adapting the proposed optimization algorithm to the IRS channel uncertainties that may exist in practical systems. Using advanced tools from convex optimization theory, the constraints containing uncertainty are transformed to their equivalent linear matrix inequalities (LMIs) to account for the channels' uncertainty radius. The results presented quantify the benefits of IRS-ISAC systems under various conditions and demonstrate the effectiveness of the proposed algorithm.
摘要
“嵌入式感测和通信（ISAC）技术提供了未来无线网络中频率压力问题的有效解决方案。这篇文章研究了智能反射表（IRS）与ISAC系统的集成，以提高雷达和通信服务的性能。具体来说，我们研究了一种由多个antenna基站（BS）和IRS共同实现的IRS-助け过 ISAC系统。在这种系统中，BS使用多个antenna执行多个目标检测和多个用户通信。我们提出了一种低复杂度和高效的集成传输扩张和反射扩张的优化方法。这种优化方法是将BS的扩张和IRS的反射矩阵优化到最小化 Frobenius 距离 между发射信号的covariance矩阵和 Desired 雷达波形矩阵。这种优化目的是满足通信用户的信号噪干扰比（SINR）约束、BS的总发射功率限制和IRS的单位模数约束。为解决这个复杂非 convex 优化问题，我们提出了一种高效的 alternate 优化（AO）算法，该算法结合分数编程（FP）、半definite 编程（SDP）和第二个 cone 编程（SOCP）方法。此外，我们还提出了IRS-ISAC系统中的Robust 扩张优化，该算法通过将uncertainty 约束转化为其等效的线性matrix inequality（LMIs）来考虑实际系统中的频率uncertainty。结果表明，在不同条件下，IRS-ISAC系统具有显著的优势，并且提出的算法效果扎实。”
Consensus-based Distributed Variational Multi-object Tracker in Multi-Sensor Network
results: 实验结果表明，我们提出的分布式变分追踪器和中央整合式追踪器的跟踪精度相当，并且分布式追踪器比 arithmetic sensor fusion 和平均协议融合策略更高。Abstract
The growing need for accurate and reliable tracking systems has driven significant progress in sensor fusion and object tracking techniques. In this paper, we design two variational Bayesian trackers that effectively track multiple targets in cluttered environments within a sensor network. We first present a centralised sensor fusion scheme, which involves transmitting sensor data to a fusion center. Then, we develop a distributed version leveraging the average consensus algorithm, which is theoretically equivalent to the centralised sensor fusion tracker and requires only local message passing with neighbouring sensors. In addition, we empirically verify that our proposed distributed variational tracker performs on par with the centralised version with equal tracking accuracy. Simulation results show that our distributed multi-target tracker outperforms the suboptimal distributed sensor fusion strategy that fuses each sensor's posterior based on arithmetic sensor fusion and an average consensus strategy.
摘要
随着准确和可靠的跟踪系统的需求不断增长，感知融合和目标跟踪技术也得到了重要的进步。在这篇论文中，我们设计了两种变分极 bayesian跟踪器，可以有效地跟踪多个目标在杂乱环境中的感知网络中。我们首先提出了一种中央感知融合方案，其中感知数据被传输到融合中心进行融合。然后，我们开发了分布式版本，利用平均协议算法，这是中央感知融合器的理论等价，只需在与邻居感知器进行本地消息传递。此外，我们验证了我们的提议的分布式变分跟踪器和中央版本之间的跟踪精度相等。 simulation结果显示，我们的分布式多目标跟踪器比使用 arithmetic sensor fusion和平均协议策略来进行分布式感知融合的优化策略强。
Delay-Doppler Alignment Modulation for Spatially Sparse Massive MIMO Communication
results: 本文首先表明，通过应用路径基本零做（ZF）预编码和接收 combine，DDAM可以将原始时变频Selective通道转化为时间 invariants ISI-free通道。 derive了必要和/或 suficient conditionsto achieve这种转化。然后，提供了一个 asymptotic analysis，表明当基站天线数量远大于通道路径数量时，DDAM可以实现时间 invariants ISI-free通道，只需要简单的延迟-Doppler补做和路径基本 MRT beamforming。此外，为了实现DDAM设计中的一些可容忍的 ISI，将路径基本预编码和接收 combine矩阵优化为最大化spectral efficiency。Abstract
Delay alignment modulation (DAM) is an emerging technique for achieving inter-symbol interference (ISI)-free wideband communications using spatial-delay processing, without relying on channel equalization or multi-carrier transmission. However, existing works on DAM only consider multiple-input single-output (MISO) communication systems and assume time-invariant channels. In this paper, by extending DAM to time-variant frequency-selective multiple-input multiple-output (MIMO) channels, we propose a novel technique termed \emph{delay-Doppler alignment modulation} (DDAM). Specifically, by leveraging \emph{delay-Doppler compensation} and \emph{path-based beamforming}, the Doppler effect of each multi-path can be eliminated and all multi-path signal components may reach the receiver concurrently and constructively. We first show that by applying path-based zero-forcing (ZF) precoding and receive combining, DDAM can transform the original time-variant frequency-selective channels into time-invariant ISI-free channels. The necessary and/or sufficient conditions to achieve such a transformation are derived. Then an asymptotic analysis is provided by showing that when the number of base station (BS) antennas is much larger than that of channel paths, DDAM enables time-invariant ISI-free channels with the simple delay-Doppler compensation and path-based maximal-ratio transmission (MRT) beamforming. Furthermore, for the general DDAM design with some tolerable ISI, the path-based transmit precoding and receive combining matrices are optimized to maximize the spectral efficiency. Numerical results are provided to compare the proposed DDAM technique with various benchmarking schemes, including MIMO-orthogonal time frequency space (OTFS), MIMO-orthogonal frequency-division multiplexing (OFDM) without or with carrier frequency offset (CFO) compensation, and beam alignment along the dominant path.
摘要
延迟对齐模ulation（DAM）是一种emerging技术，用于实现干扰符号（ISI）free广泛通信，只需通过空间延迟处理，而不需依赖通道均衡或多 carriermultiplexing。然而，现有的DAM研究仅考虑多input single-output（MISO）通信系统，并假设时variant channels。在这篇文章中，我们通过扩展DAM到时variant frequency-selective多input多output（MIMO）通信频道，提出一种新的技术，称为延迟Doppler对齐模ulation（DDAM）。具体来说，通过利用延迟Doppler补做和路径基 beamforming，每个多路可以消除Doppler效应，使所有多路信号组件能够同时到达接收器并构成。我们首先示出，通过应用路径基Zero-Forcing（ZF）预编码和接收 combining，DDAM可以将原始时variant frequency-selective频道变换成时 invariantin ISI-free频道。我们 derive了必要和/或充分的条件以实现这种变换。然后，我们提供了一种 asymptotic analysis，表明当基站天线数量比channel path数量多得多时，DDAM可以将时variant ISI-free频道转换成时 invariantin ISI-free频道，只需使用简单的延迟Doppler补做和路径基MRT beamforming。此外，为了设计DDAM，我们 optimize了路径基传输预编码和接收 combining矩阵，以最大化spectral efficiency。我们提供了一些数值结果，并与various benchmarking schemes进行比较，包括MIMO-orthogonal time frequency space（OTFS）、MIMO-orthogonal frequency-division multiplexing（OFDM）without/with carrier frequency offset（CFO）compensation，以及beam alignment along the dominant path。