2,926 research outputs found
Image processing techniques as a support to transmitter positioning determination in cognitive radio networks
Cognitive radio is a new paradigm for wireless communications offering a solution to conciliate the current spectrum demand growth and underutilization without changes to the existing legacy wireless systems. Secondary users should be able to identify spatial and temporal spectrum holes not occupied by primary users and use them
opportunistically, without generating interference to primary receivers. For that purpose, having knowledge of the primary
network is required to ensure an appropriate secondary user operation. In this context, and assuming there is no cooperation between primary and secondary networks, this paper proposes a new framework, based on image processing techniques, aimed at combining a number of sensed samples at different geographical positions collected by secondary sensors, in order to estimate the positions of the different primary transmitters. The results can be used to discover frequencies that can be used by a secondary network without disturbing
primary receivers. Our results, performed in a realistic scenario, show the efficacy of the proposed framework in estimating transmitter positions.Peer ReviewedPostprint (published version
Software Defined Radio Implementation Of Ds-Cdma In Inter-Satellite Communications For Small Satellites
The increased usage of CubeSats recently has changed the communication philosophy from long-range point-to-point propagations to a multi-hop network of small orbiting nodes. Separating system tasks into many dispersed satellites can increase system survivability, versatility, configurability, adaptability, and autonomy. Inter-satellite links (ISL) enable the satellites to exchange information and share resources while reducing the traffic load to the ground. Establishment and stability of the ISL are impacted by factors such as the satellite orbit and attitude, antenna configuration, constellation topology, mobility, and link range. Software Defined Radio (SDR) is beginning to be heavily used in small satellite communications for applications such as base stations. A software-defined radio is a software program that does the functionality of a hardware system. The digital signal processing blocks are incorporated into the software giving it more flexibility and modulation. With this, the idea of a remote upgrade from the ground as well as the potential to accommodate new applications and future services without hardware changes is very promising. Realizing this, my idea is to create an inter-satellite link using software defined radio. The advantages of this are higher data rates, modification of operating frequencies, possibility of reaching higher frequency bands for higher throughputs, flexible modulation, demodulation and encoding schemes, and ground modifications. However, there are several challenges in utilizing the software-defined radio to create an inter-satellite link communication for small satellites. In this paper, we designed and implemented a multi-user inter-satellite communication network using SDRs, where Code Division Multiple Access (CDMA) technique is utilized to manage the multiple accesses to shared communication channel among the satellites. This model can be easily reconfigured to support any encoding/decoding, modulation, and other signal processing schemes
Software Defined Radio Implementation Of Ds-Cdma In Inter-Satellite Communications For Small Satellites
The increased usage of CubeSats recently has changed the communication philosophy from long-range point-to-point propagations to a multi-hop network of small orbiting nodes. Separating system tasks into many dispersed satellites can increase system survivability, versatility, configurability, adaptability, and autonomy. Inter-satellite links (ISL) enable the satellites to exchange information and share resources while reducing the traffic load to the ground. Establishment and stability of the ISL are impacted by factors such as the satellite orbit and attitude, antenna configuration, constellation topology, mobility, and link range. Software Defined Radio (SDR) is beginning to be heavily used in small satellite communications for applications such as base stations. A software-defined radio is a software program that does the functionality of a hardware system. The digital signal processing blocks are incorporated into the software giving it more flexibility and modulation. With this, the idea of a remote upgrade from the ground as well as the potential to accommodate new applications and future services without hardware changes is very promising. Realizing this, my idea is to create an inter-satellite link using software defined radio. The advantages of this are higher data rates, modification of operating frequencies, possibility of reaching higher frequency bands for higher throughputs, flexible modulation, demodulation and encoding schemes, and ground modifications. However, there are several challenges in utilizing the software-defined radio to create an inter-satellite link communication for small satellites. In this paper, we designed and implemented a multi-user inter-satellite communication network using SDRs, where Code Division Multiple Access (CDMA) technique is utilized to manage the multiple accesses to shared communication channel among the satellites. This model can be easily reconfigured to support any encoding/decoding, modulation, and other signal processing schemes
A Tutorial on Environment-Aware Communications via Channel Knowledge Map for 6G
Sixth-generation (6G) mobile communication networks are expected to have
dense infrastructures, large-dimensional channels, cost-effective hardware,
diversified positioning methods, and enhanced intelligence. Such trends bring
both new challenges and opportunities for the practical design of 6G. On one
hand, acquiring channel state information (CSI) in real time for all wireless
links becomes quite challenging in 6G. On the other hand, there would be
numerous data sources in 6G containing high-quality location-tagged channel
data, making it possible to better learn the local wireless environment. By
exploiting such new opportunities and for tackling the CSI acquisition
challenge, there is a promising paradigm shift from the conventional
environment-unaware communications to the new environment-aware communications
based on the novel approach of channel knowledge map (CKM). This article aims
to provide a comprehensive tutorial overview on environment-aware
communications enabled by CKM to fully harness its benefits for 6G. First, the
basic concept of CKM is presented, and a comparison of CKM with various
existing channel inference techniques is discussed. Next, the main techniques
for CKM construction are discussed, including both the model-free and
model-assisted approaches. Furthermore, a general framework is presented for
the utilization of CKM to achieve environment-aware communications, followed by
some typical CKM-aided communication scenarios. Finally, important open
problems in CKM research are highlighted and potential solutions are discussed
to inspire future work
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