Remote sensing lightweight foundation models have successfully achieved online perception, providing real-time intelligent interpretation. However, their capabilities are restricted to inferences solely based on their respective observations and models, thus lacking a comprehensive understanding of large-scale remote sensing scenarios. To address this limitation, we propose RingMo-Galaxy, a remote sensing distributed foundation model based on generalized information mapping and interaction. RingMo-Galaxy can realize online collaborative perception across multiple platforms and diverse downstream tasks by mapping observations into a unified space and implementing a task-agnostic information interaction strategy. Specifically, we leverage the ground-based geometric prior of remote sensing oblique observations to change feature mapping from absolute to relative depth estimation, thereby enhancing the model’s ability to extract generalized features across diverse heights and perspectives. In addition, we present a dual-branch information compression module to decouple high-frequency and low-frequency features, achieving feature-level compression while preserving critical task-agnostic details. To support our research, we collect a multitask simulation dataset named AirCo-MultiTasks, specifically designed for multi-unmanned aerial vehicle (UAV) collaborative observation. We also conduct extensive experiments, including 3-D object detection, instance segmentation, and trajectory prediction. The numerous results demonstrate that our proposed RingMo-Galaxy achieves state-of-the-art performance across various downstream tasks.

In this paper, we consider a cooperative sensing framework in the context of future multi-functional network with both communication and sensing ability, where one base station (BS) serves as a sensing transmitter and several nearby BSs serve as sensing receivers. Each receiver receives the sensing signal reflected by the target and communicates with the fusion center (FC) through a backhaul-limited multiple access channel (MAC) for cooperative localization of the target. Different from schemes on only information domain or signal domain cooperation, we present a hybrid information-signal domain cooperative sensing (HISDCS) design, where each sensing receiver transmits both the estimated time delay/effective reflecting coefficient and the received sensing signal sampled around the estimated time delay to the FC. Then, we propose to minimize the number of channel uses by utilizing an efficient Karhunen-Loéve transformation (KLT) encoding scheme for signal quantization and proper node selection, under the Cramér-Rao lower bound (CRLB) constraint and the capacity limits of MAC. A novel matrix-inequality constrained successive convex approximation (MCSCA) algorithm is proposed to optimize the backhaul resource allocation, together with a greedy strategy for node selection. Finally, numerical simulations are presented to show that the proposed HISDCS design is able to outperform the baseline schemes significantly.

The Graph Attention Network (GAT), based on the foundational principles of Graph Neural Network (GNN), represents a significant advancement in the accurate representation and in-depth understanding of complex data structures. However, GAT can’t proficiently handle heterogeneous data, which negatively affects model performance. Existing solutions incur substantial computational overhead when addressing these challenges, compromising efficiency and impeding practical deployment. In this paper, we propose Zephyr to enable GAT to efficiently process heterogeneous data with high performance. In Zephyr, we introduce Dynamic Multi-matrix Design and Spatial Multi-activation Design to eliminate the effects of finiteness of matrix representation capability and difference in heterogeneous spaces. Remarkably, Zephyr shows superior capability in processing heterogeneous data while requiring minimal storage space. Through comprehensive simulations and comparisons with existing schemes, Zephyr demonstrates a substantial performance improvement, increasing accuracy by over 8% on heterogeneous datasets and enhancing fitting speed by approximately 20%. Moreover, with heterogeneous data, it maintains memory overhead below 1.05x and curtails time overhead to 70%.

Nowadays, wafer fabrication in semiconductor manufacturing is highly dependent on cluster tools. A cluster tool is equipped with several process modules (PMs) and a wafer handling robot. When the tool is operating, generally each PM is processing a wafer, and the robot is responsible for delivering the wafers from one PM to another. Thus, when a wafer is completed in a PM, the robot may be busy for performing other tasks such that it cannot immediately unload the completed wafer in the PM, resulting in that the wafer has to stay there for some extra time. The processing time of a wafer together with its delay time for waiting for the robot’s arrival for unloading is defined as wafer residency time in a PM. However, a long wafer delay time may deteriorate its quality. Therefore, it is highly desired and important to reduce the wafer delay time at each step as much as possible. This work aims to tackle this important issue for single-arm cluster tools (SACTs). Specifically, by using a Petri net model, this work analyzes the steady-state operational behavior of an SACT under the backward and earliest starting strategies. It is found that there must exist wafer delay time at the steps in the upstream of the bottleneck step, and such wafer delay time can be reduced by properly adjusting the robot waiting time. Thus, three algorithms are developed to reduce the wafer delay time at each step as much as possible by properly assigning the robot idle time. Finally, the application of the proposed method is illustrated by using examples.Note to Practitioners—In a modern semiconductor fab, there are hundreds of cluster tools for wafer fabrication. To ensure wafer quality, it is important to reduce the wafer delay time in PMs of cluster tools after a wafer is processed since the high temperature, chemical gas, and particles in the PMs may damage the wafer. To do so, this work proposes three algorithms with polynomial complexity to assign the robot idle time as robot waiting time such that the wafer delay time in PMs can be reduced as much as possible. Furthermore, the obtained schedule by these algorithms is optimal in terms of the cycle time. Besides, the developed algorithms can be easily embedded into the controller of cluster tools by facility engineers. Therefore, this work has a practical value.

Bianchi's 2-Dimesional Markov model has laid the foundation for analysis of 802.11 CSMA/CA mechanism. However, the assumption that every station is saturated significantly degrades the accuracy of it since it is quite possible that the network exists in heterogeneous saturation status where some types of traffics are extremely saturated while other types of traffics are far from saturation. Although there are several analytical models under non-saturated assumption by introducing a constant probability that the station has packets awaiting transmission, they share two common weaknesses: the possibility of multiple packets arriving and the constant probability that a station has packet to send. Thus we establish a 3-Dimensional Markov model that introduces an additional Dimensional, the queue length, to solve them. We validated our analytical results of performance metrics of 802.11 under homogeneous and heterogeneous traffics by extensive simulations.

IEEE 802.11 distributed coordination function (DCF) is the most popular medium access control (MAC) protocol in distributed wireless networks, in which the wireless medium is shared. But the throughput of the network is restrained because of collisions and the idle time slots wasted for competition. In this paper, we present a new medium access protocol with a busy tone (MABT)1. In this protocol, the backoff procedure is executed in the busy tone instead of the data channel, so there is almost no wasted time slot in the data channel. Besides, this paper also introduces a modified backoff algorithm different with that of IEEE 802.11 DCF. By this backoff algorithm, the probability of packet collision can be significantly reduced. A remarkable characteristic of this protocol is that it does not require extra transceiver for the busy tone, which doesn't increase the hardware cost of the mobile station. We study the performance of MABT protocol through simulated experiments. The results show that MABT protocol is more efficient than the one discussed in the IEEE 802.11e task group.

IEEE 802.11e standard has defined EDCA to guarantee prioritized QoS by service differentiation. However, it induces significant performance deterioration in both delay performance and collision probability at heavy load due to inherent drawbacks of binary exponential backoff (BEB) scheme. In this paper we proposed a novel backoff scheme, channel collision based adaptive backoff (CCBAB)1 scheme which compels each station to react to channel collisions irrespective of whether or not it is involved in, to combat the deterioration problem. CCBAB selectively forces some uncollided traffics to reduce their transmission probability and grants collided real time traffics larger transmission probability to ensure them be successfully transmitted in a shorter time. Simulations demonstrate that CCBAB scheme achieves more stable channel collision probabilities, smaller delay and jitter for real time traffics than EDCA and its enhanced variation AEDCF schemes and proves to be more resistant towards collisions and delay deterioration at high congestion level.

IEEE 802.11 standard is the most popular medium access control (MAC) protocol in distributed wireless networks. But the throughput of the network is restrained because of collisions and the idle slots wasted for competition. In this paper, we present a new Distributed Medium Access protocol with a busy tone (DMABT). In this protocol, a new backoff procedure is executed in the busy tone instead of the data channel and collision is reduced, so the throughput of the network is improved. A remarkable characteristic of this protocol is that it does not require extra transceiver for the busy tone, which does not increase the hardware cost of the mobile station. We study the performance of DMABT protocol through simulated experiments. The results show that DMABT protocol is more efficient than the one discussed in the IEEE 802.11e task group.

In non-infrastructure WLANs low network capacity and lack of QoS guarantee are the bottlenecks of commonly used contention access protocols. In this paper, we proposed a novel MAC protocol, the Delegate Polling Hybrid Access (DPHA)1protocol, which uses a distributed polling-based access scheme, delegate polling access scheme, to avoid collisions and adopt contention access scheme as a complement when wrong polling decisions occur. We designed a feasible delegate polling access scheme in non-infrastructure networks, which lets the current transmitting Traffic Stream (TS) delegate the AP to select the next transmitting TS based on a polling algorithm and announce it in the data packet header. The elaborately designed polling algorithm employs conditional service differentiation to improve fairness for best effort traffics and overcomes the drawbacks of existing polling algorithms. Simulation results demonstrate that DPHA protocol can significantly improve network capacity and QoS performance for all kinds of traffics.

In traditional ad hoc networks, the hidden-terminal and the exposed-terminal problems can reduce the network capacity severely on the MAC layer. To address the problem, many MAC schemes have been proposed such as RTS/CTS dialogue and DBTMA protocol. Among these protocols, the DBTMA protocol has solved the hidden- and the exposed- terminal problems perfectly. However, the DBTMA protocol occupies two separate busy tone channels to address the hidden- and the exposed-terminal problems, and therefore causes a waste of channel. In this paper, we propose a new MAC protocol, termed the combined dual busy tone multiple access (CDBTMA). In our proposed CDBTMA protocol, the DBTMA protocol is modified, using only one busy tone channel to implement all functions which the DBTMA protocol has, without significant loss on performance.