218 research outputs found
Enhanced Trellis Coded Multiple Access (ETCMA)
We propose an enhanced version of trellis coded multiple access (TCMA), an
overloaded multiple access scheme that outperforms the original TCMA in terms
of achieved spectral efficiency. Enhanced TCMA (ETCMA) performs simultaneous
transmission of multiple data streams intended for users experiencing similar
signal-to-noise ratios and can be employed both in the uplink and in the
downlink of wireless systems, thus overcoming one of the main limitations of
TCMA. Thanks to a new receiver algorithm, ETCMA is capable of delivering a
significantly higher spectral efficiency. We show that ETCMA approaches the
capacity of the Additive White Gaussian Noise channel for a wide range of
signal-to-noise ratios.Comment: 5 pages, 5 figure
Analysis and Evaluation of Pattern Division Multiple Access Scheme Jointed With 5G Waveforms
Nonorthogonal multiple access (NOMA) techniques represent a key feature for 5G systems in order to increase multiple users' systems' capacity. In particular, we propose, for study, a pattern division multiple access (PDMA) technique, which denes a pattern matrix used for mapping the users to a group of resource elements that might be shared by multiple users. The contribution of this paper is the analysis of the performances, in terms of bit error rate (BER), of 5G candidate waveforms, such as orthogonal frequency division multiplexing (OFDM), lter bank multi-carrier (FBMC), and generalized frequency division multiplexing (GFDM), in the PDMA scheme. Regarding the detection of different users' data, the successive interference cancellation algorithm is performed at the receiver side. The simulation results, consolidated by the analytic study, exhibit that OFDM and FBMC could be used in the NOMA context, while the BER related to GFDM is very high
Hybrid generalized non-orthogonal multiple access for the 5G wireless networks.
Master of Science in Computer Engineering. University of KwaZulu-Natal. Durban, 2018.The deployment of 5G networks will lead to an increase in capacity, spectral efficiency, low latency
and massive connectivity for wireless networks. They will still face the challenges of resource and
power optimization, increasing spectrum efficiency and energy optimization, among others.
Furthermore, the standardized technologies to mitigate against the challenges need to be developed
and are a challenge themselves. In the current predecessor LTE-A networks, orthogonal frequency
multiple access (OFDMA) scheme is used as the baseline multiple access scheme. It allows users to
be served orthogonally in either time or frequency to alleviate narrowband interference and impulse
noise. Further spectrum limitations of orthogonal multiple access (OMA) schemes have resulted in
the development of non-orthogonal multiple access (NOMA) schemes to enable 5G networks to
achieve high spectral efficiency and high data rates. NOMA schemes unorthogonally co-multiplex
different users on the same resource elements (RE) (i.e. time-frequency domain, OFDMA subcarrier,
or spreading code) via power domain (PD) or code domain (CD) at the transmitter and successfully
separating them at the receiver by applying multi-user detection (MUD) algorithms. The current
developed NOMA schemes, refered to as generalized-NOMA (G-NOMA) technologies includes;
Interleaver Division Multiple Access (IDMA, Sparse code multiple access (SCMA), Low-density
spreading multiple access (LDSMA), Multi-user shared access (MUSA) scheme and the Pattern
Division Multiple Access (PDMA). These protocols are currently still under refinement, their
performance and applicability has not been thoroughly investigated. The first part of this work
undertakes a thorough investigation and analysis of the performance of the existing G-NOMA
schemes and their applicability.
Generally, G-NOMA schemes perceives overloading by non-orthogonal spectrum resource
allocation, which enables massive connectivity of users and devices, and offers improved system
spectral efficiency. Like any other technologies, the G-NOMA schemes need to be improved to
further harvest their benefits on 5G networks leading to the requirement of Hybrid G-NOMA
(G-NOMA) schemes. The second part of this work develops a HG-NOMA scheme to alleviate the
5G challenges of resource allocation, inter and cross-tier interference management and energy
efficiency. This work develops and investigates the performance of an Energy Efficient HG-NOMA
resource allocation scheme for a two-tier heterogeneous network that alleviates the cross-tier
interference and improves the system throughput via spectrum resource optimization. By considering
the combinatorial problem of resource pattern assignment and power allocation, the HG-NOMA
scheme will enable a new transmission policy that allows more than two macro-user equipment’s
(MUEs) and femto-user equipment’s (FUEs) to be co-multiplexed on the same time-frequency RE
increasing the spectral efficiency. The performance of the developed model is shown to be superior to
the PD-NOMA and OFDMA schemes
Turbo-like Iterative Multi-user Receiver Design for 5G Non-orthogonal Multiple Access
Non-orthogonal multiple access (NoMA) as an efficient way of radio resource
sharing has been identified as a promising technology in 5G to help improving
system capacity, user connectivity, and service latency in 5G communications.
This paper provides a brief overview of the progress of NoMA transceiver study
in 3GPP, with special focus on the design of turbo-like iterative multi-user
(MU) receivers. There are various types of MU receivers depending on the
combinations of MU detectors and interference cancellation (IC) schemes.
Link-level simulations show that expectation propagation algorithm (EPA) with
hybrid parallel interference cancellation (PIC) is a promising MU receiver,
which can achieve fast convergence and similar performance as message passing
algorithm (MPA) with much lower complexity.Comment: Accepted by IEEE 88th Vehicular Technology Conference (IEEE VTC-2018
Fall), 5 pages, 6 figure
Decision Feedback Aided Bayesian Turbo Space-Time Equalizer for Parallel Interference Cancellation in SDMA Systems
A novel Bayesian Decision-Feedback aided turbo Space-Time Equalizer (DF-STE) combined with a Parallel Interference Cancellation (PIC) scheme and designed for multiple antenna assisted receivers is introduced. The proposed receiver structure allows the employment of a non-linear Bayesian turbo DF-STE operating at a moderate computational cost, which outperforms the linear turbo detector benchmarker based on the Minimum Mean-Squared Error (MMSE) criterion, even if the latter aims for jointly detecting all transmitters’ signals
Compressed television transmission: A market survey
NASA's compressed television transmission technology is described, and its potential market is considered; a market that encompasses teleconferencing, remote medical diagnosis, patient monitoring, transit station surveillance, as well as traffic management and control. In addition, current and potential television transmission systems and their costs and potential manufacturers are considered
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