9 research outputs found
Spatially-Coupled Nearly-Regular LDPC Code Ensembles for Rate-Flexible Code Design
Spatially coupled regular LDPC code ensembles have outstanding performance with belief propagation decoding and can perform close to the Shannon limit. In this paper we investigate the suitability of coupled regular LDPC code ensembles with respect to rate-flexibility. Regular ensembles with good performance and low complexity exist for a variety of specific code rates. On the other hand it can be observed that outside this set of favorable rational rates the complexity and performance become unreasonably high. We therefore propose ensembles with slight irregularity that allow us to smoothly cover the complete range of rational rates. Our simple construction allows a performance with negligible gap to the Shannon limit while maintaining complexity as low as for the best regular code ensembles. At the same time the construction guarantees that asymptotically the minimum distance grows linearly with the length of the coupled blocks
Rate-Compatible Spatially-Coupled LDPC Code Ensembles With Nearly-Regular Degree Distributions
Spatially-coupled regular LDPC code ensembles have outstanding performance with belief propagation decoding and can perform arbitrarily close to the Shannon limit without requiring irregular graph structures. In this paper, we are concerned with the performance and complexity of spatially-coupled ensembles with a rate-compatibility constraint. Spatially-coupled regular ensembles that support rate-compatibility through extension have been proposed before and show very good performance if the node degrees and the coupling width are chosen appropriately. But due to the strict constraint of maintaining a regular degree, there exist certain unfavorable rates that exhibit bad performance and high decoding complexity. We introduce an altered LDPC ensemble construction that changes the evolution of degrees over subsequent incremental redundancy steps in such a way, that the degrees can be kept low to achieve outstanding performance close to Shannon limit for all rates. These ensembles always outperform their regular counterparts at small coupling width
Spatially coupled protograph-based ldpc codes for incremental redundancy
Abstract-We investigate a family of protograph based ratecompatible LDPC convolutional codes. The code family shows improved thresholds close to the Shannon limit compared to their uncoupled versions for the binary erasure channel as well as the AWGN channel. In fact, the gap to Shannon limit is almost uniform for all members of the code family ensuring good performance for all subsequent incremental redundancy transmissions. Compared to similar code families based on regular LDPC codes [1] the complexity of our approach grows slower for the considered rates
Software-based implementation of dual connectivity for LTE
© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.One of the major challenges of current mobile networks is to increase the per-user data rate without significant infrastructure cost and using the already existing physical resources, i.e., the bandwidth. In this sense, Dual Connectivity emerges as a promising solution for LTE and future 5G to increase the throughput with minor changes in current systems. This work presents the implementation of the U-Plane of Dual Connectivity for LTE using the open source software Open Air Interface with commodity hardware and the impact of this technology on UDP and TCP performance.This work has been supported by the European Project DualConnectivity Solution for ORCA (DALI) as part of the OpenCall 2 of H2020-ICT-2016-2017 (ORCA) project.Peer Reviewe
Implementation of the 3GPP LTE-WLAN Interworking Protocols in NS-3
The next generation wireless standard, called Fifth Generation (5G), is being
designed to encompass Heterogeneous Networks (HetNets) architectures consisting
of a single holistic network with Multiple Radio Access Technologies
(Multi-RAT). Multiple connectivity protocols and spectrum would be managed from
a common core (management system) handling both: i) traditional macro cellular
systems (such as LTE), that can provide long-range, outdoor coverage, as well
as ii) low-power wireless systems with high capacity (such as Wi-Fi), that can
be deployed to cater indoor traffic needs. 5G HetNets are expected to achieve
ubiquitous connectivity that would guarantee Quality of Service (QoS), Quality
of Experience (QoE) along with efficient use of spectrum and energy at low
cost. Tightly coupled LTE-Wi-Fi networks have emerged as one of the promising
solutions in the 5G era to boost network capacity and improve end user's
quality of experience. LTE/Wi-Fi Link Aggregation (LWA) and LTE WLAN Radio
Level Integration with IPSec Tunnel (LWIP) are two approaches put forward by
the 3rd Generation Partnership Project (3GPP) to enable flexible, general, and
scalable LTE-WLAN inter-working. These techniques enable operator-controlled
access of licensed and unlicensed spectrum and allow transparent access of
operator's evolved core. The most important aspect of these techniques is that
they could be enabled with straightforward software upgrades and can utilize
the already existing Wi-Fi networks. This article presents and motivates the
design details of LWA and LWIP protocols. We also present the first NS-3 LWA
and LWIP implementations over Network Simulator 3 (NS-3). In particular, this
work focuses on the adaptation and concurrent usage of different NS-3 modules
and protocols of different technologies to enable the support of these
interworking schemes