1,981 research outputs found
Channelization for Multi-Standard Software-Defined Radio Base Stations
As the number of radio standards increase and spectrum resources come under more pressure, it becomes ever less efficient to reserve bands of spectrum for exclusive use by a single radio standard. Therefore, this work focuses on channelization structures compatible with spectrum sharing among multiple wireless standards and dynamic spectrum allocation in particular. A channelizer extracts independent communication channels from a wideband signal, and is one of the most computationally expensive components in a communications receiver. This work specifically focuses on non-uniform channelizers suitable for multi-standard Software-Defined Radio (SDR) base stations in general and public mobile radio base stations in particular.
A comprehensive evaluation of non-uniform channelizers (existing and developed during the course of this work) shows that parallel and recombined variants of the Generalised Discrete Fourier Transform Modulated Filter Bank (GDFT-FB) represent the best trade-off between computational load and flexibility for dynamic spectrum allocation. Nevertheless, for base station applications (with many channels) very high filter orders may be required, making the channelizers difficult to physically implement.
To mitigate this problem, multi-stage filtering techniques are applied to the GDFT-FB. It is shown that these multi-stage designs can significantly reduce the filter orders and number of operations required by the GDFT-FB. An alternative approach, applying frequency response masking techniques to the GDFT-FB prototype filter design, leads to even bigger reductions in the number of coefficients, but computational load is only reduced for oversampled configurations and then not as much as for the multi-stage designs. Both techniques render the implementation of GDFT-FB based non-uniform channelizers more practical.
Finally, channelization solutions for some real-world spectrum sharing use cases are developed before some final physical implementation issues are considered
Non-Uniform Channelization Methods for Next Generation SDR PMR Base Stations
Channelization in multi-standard Software-Defined
Radio base stations presents a significant challenge. In this
paper, two different channelization structures designed for a
multi-standard SDR base station are studied. As a basis for
comparing their computational efficiency and
reconfigurability, both are applied to a specific case study of a
TETRA and TEDS standards base station. Uniform narrow
band spectrum division followed by channel recombination
demonstrates greater flexibility than a non-uniform parallel
spectrum division alternative. However, computational
advantages between both structures depend on the channel
allocation patterns considered
Practical Non-Uniform Channelization for Multistandard Base Stations
A Multistandard software-defined radio base station must perform non-uniform channelization of multiplexed frequency bands. Non-uniform
channelization accounts for a significant portion of the digital signal processing workload in the base station receiver and can be difficult to realize in a physical
implementation. In non-uniform channelization methods based on generalized DFT filter banks, large prototype filter orders are a significant issue for
implementation. In this paper, a multistage filter design is applied to two different non-uniform generalized DFT-based channelizers in order to reduce their filter
orders. To evaluate the approach, a TETRA and TEDS base station is used. Experimental results show that the new multistage design reduces both the number
of coefficients and operations and leads to a more feasible design and practical physical implementation
Practical Non-Uniform Channelization for Multistandard Base Stations
A Multistandard software-defined radio base station must perform non-uniform channelization of multiplexed frequency bands. Non-uniform
channelization accounts for a significant portion of the digital signal processing workload in the base station receiver and can be difficult to realize in a physical
implementation. In non-uniform channelization methods based on generalized DFT filter banks, large prototype filter orders are a significant issue for
implementation. In this paper, a multistage filter design is applied to two different non-uniform generalized DFT-based channelizers in order to reduce their filter
orders. To evaluate the approach, a TETRA and TEDS base station is used. Experimental results show that the new multistage design reduces both the number
of coefficients and operations and leads to a more feasible design and practical physical implementation
Efficient Channelization for PMR+4G and GSM Re-Farming Base Stations
Current trends in mobile communications look for a better usage of the frequency spectrum by diverging from the classic frequency bands division for each standard. Instead, sharing a same frequency band by several mobile standards has been motivated by several factors: under-utilisation of some frequency bands, better electromagnetic propagation properties and provision of new capabilities to existing standards. This new way to manage the electromagnetic spectrum has an influence in the devices which form the mobile radio interface: base stations and mobiles stations. In particular for base stations, channelization represents an important challenge. In this paper efficient channelization techniques are proposed as a practical solution for real world professional and commercial mobile communication cases where frequency bands are shared. Depending on each case, the most optimal solution is based on the application of one of these channelization techniques, or a combination of several of them
A baseband wireless spectrum hypervisor for multiplexing concurrent OFDM signals
The next generation of wireless and mobile networks will have to handle a significant increase in traffic load compared to the current ones. This situation calls for novel ways to increase the spectral efficiency. Therefore, in this paper, we propose a wireless spectrum hypervisor architecture that abstracts a radio frequency (RF) front-end into a configurable number of virtual RF front ends. The proposed architecture has the ability to enable flexible spectrum access in existing wireless and mobile networks, which is a challenging task due to the limited spectrum programmability, i.e., the capability a system has to change the spectral properties of a given signal to fit an arbitrary frequency allocation. The proposed architecture is a non-intrusive and highly optimized wireless hypervisor that multiplexes the signals of several different and concurrent multi-carrier-based radio access technologies with numerologies that are multiple integers of one another, which are also referred in our work as radio access technologies with correlated numerology. For example, the proposed architecture can multiplex the signals of several Wi-Fi access points, several LTE base stations, several WiMAX base stations, etc. As it able to multiplex the signals of radio access technologies with correlated numerology, it can, for instance, multiplex the signals of LTE, 5G-NR and NB-IoT base stations. It abstracts a radio frequency front-end into a configurable number of virtual RF front ends, making it possible for such different technologies to share the same RF front-end and consequently reduce the costs and increasing the spectral efficiency by employing densification, once several networks share the same infrastructure or by dynamically accessing free chunks of spectrum. Therefore, the main goal of the proposed approach is to improve spectral efficiency by efficiently using vacant gaps in congested spectrum bandwidths or adopting network densification through infrastructure sharing. We demonstrate mathematically how our proposed approach works and present several simulation results proving its functionality and efficiency. Additionally, we designed and implemented an open-source and free proof of concept prototype of the proposed architecture, which can be used by researchers and developers to run experiments or extend the concept to other applications. We present several experimental results used to validate the proposed prototype. We demonstrate that the prototype can easily handle up to 12 concurrent physical layers
Smart antennas in software radio base stations
The application of adaptive antenna techniques to fixed-architecture base stations has been shown to offer wide-ranging benefits, including interference rejection capabilities or increased coverage and spectral efficiency.
Unfortunately, the actual implementation of
these techniques to mobile communication scenarios has traditionally been set back by two fundamental reasons. On one hand, the lack of flexibility of current transceiver architectures does not allow for the introduction of advanced add-on functionalities. On the other hand, the
often oversimplified models for the spatiotemporal characteristics of the radio communications channel generally give rise to
performance predictions that are, in practice, too optimistic. The advent of software radio architectures represents a big step toward the
introduction of advanced receive/transmit
capabilities. Thanks to their inherent flexibility
and robustness, software radio architectures
are the appropriate enabling technology for the
implementation of array processing techniques.
Moreover, given the exponential progression of
communication standards in coexistence and
their constant evolution, software reconfigurability
will probably soon become the only costefficient
alternative for the transceiver
upgrade. This article analyzes the requirements
for the introduction of software radio techniques
and array processing architectures in
multistandard scenarios. It basically summarizes
the conclusions and results obtained within
the ACTS project SUNBEAM,1 proposing
algorithms and analyzing the feasibility of
implementation of innovative and softwarereconfigurable
array processing architectures in
multistandard settings.Peer Reviewe
Transceivers as a Resource: Scheduling Time and Bandwidth in Software-Defined Radio
In the future, software-defined radio may enable a mobile device to support multiple wireless protocols implemented as software applications. These applications, often referred to as waveform applications, could be added, updated, or removed from a software-radio device to meet changing demands. Current software-defined radio solutions grant an active waveform exclusive ownership of a specific transceiver or analog front-end. Since a wireless device has a limited number of front-ends, this approach puts a hard constraint on the number of concurrent waveform applications a device can support. A growing trend in software-defined radio research is to virtualize front-ends to allow sharing and reuse among active waveform applications. This poses a difficult scheduling challenge. This article proposes a new approach in which shared access to front-ends is managed by a mixed-integer linear programming model. This model ties together the technique of time-division sharing and front-end bandwidth channelization. This scheduling model is evaluated in simulation under several different scenarios and workloads. Simulation results show that the proposed approach reduces hardware contention and missed radio accesses compared to existing techniques
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