7,520 research outputs found
Performance Analysis of PCFICH and PDCCH LTE Control Channels
Control channels play a key role in the evaluation of mobile system performance. The purpose of our paper is to evaluate the performance of the control channels implementation in the Long Term Evolution (LTE) system. The paper deals with the simulation of the complete signal processing chain for Physical Control Format Indicator Channel (PCFICH) and Physical Downlink Control Channel (PDCCH) in the LTE system, Release 8. We implemented a complete signal processing chain for downlink control channels as an extension of the existing MATLAB LTE downlink simulator. The paper presents results of PCFICH and PDCCH control channel computer performance analysis in various channel conditions. The results can be compared with the performance of data channels
A Novel Beamformed Control Channel Design for LTE with Full Dimension-MIMO
The Full Dimension-MIMO (FD-MIMO) technology is capable of achieving huge
improvements in network throughput with simultaneous connectivity of a large
number of mobile wireless devices, unmanned aerial vehicles, and the Internet
of Things (IoT). In FD-MIMO, with a large number of antennae at the base
station and the ability to perform beamforming, the capacity of the physical
downlink shared channel (PDSCH) has increased a lot. However, the current
specifications of the 3rd Generation Partnership Project (3GPP) does not allow
the base station to perform beamforming techniques for the physical downlink
control channel (PDCCH), and hence, PDCCH has neither the capacity nor the
coverage of PDSCH. Therefore, PDCCH capacity will still limit the performance
of a network as it dictates the number of users that can be scheduled at a
given time instant. In Release 11, 3GPP introduced enhanced PDCCH (EPDCCH) to
increase the PDCCH capacity at the cost of sacrificing the PDSCH resources. The
problem of enhancing the PDCCH capacity within the available control channel
resources has not been addressed yet in the literature. Hence, in this paper,
we propose a novel beamformed PDCCH (BF-PDCCH) design which is aligned to the
3GPP specifications and requires simple software changes at the base station.
We rely on the sounding reference signals transmitted in the uplink to decide
the best beam for a user and ingeniously schedule the users in PDCCH. We
perform system level simulations to evaluate the performance of the proposed
design and show that the proposed BF-PDCCH achieves larger network throughput
when compared with the current state of art algorithms, PDCCH and EPDCCH
schemes
Architectures and Key Technical Challenges for 5G Systems Incorporating Satellites
Satellite Communication systems are a promising solution to extend and
complement terrestrial networks in unserved or under-served areas. This aspect
is reflected by recent commercial and standardisation endeavours. In
particular, 3GPP recently initiated a Study Item for New Radio-based, i.e., 5G,
Non-Terrestrial Networks aimed at deploying satellite systems either as a
stand-alone solution or as an integration to terrestrial networks in mobile
broadband and machine-type communication scenarios. However, typical satellite
channel impairments, as large path losses, delays, and Doppler shifts, pose
severe challenges to the realisation of a satellite-based NR network. In this
paper, based on the architecture options currently being discussed in the
standardisation fora, we discuss and assess the impact of the satellite channel
characteristics on the physical and Medium Access Control layers, both in terms
of transmitted waveforms and procedures for enhanced Mobile BroadBand (eMBB)
and NarrowBand-Internet of Things (NB-IoT) applications. The proposed analysis
shows that the main technical challenges are related to the PHY/MAC procedures,
in particular Random Access (RA), Timing Advance (TA), and Hybrid Automatic
Repeat reQuest (HARQ) and, depending on the considered service and
architecture, different solutions are proposed.Comment: Submitted to Transactions on Vehicular Technologies, April 201
Scheduling Policies in Time and Frequency Domains for LTE Downlink Channel: A Performance Comparison
A key feature of the Long-Term Evolution (LTE) system is that the packet scheduler can make use of the channel quality information (CQI), which is periodically reported by user equipment either in an aggregate form for the whole downlink channel or distinguished for each available subchannel. This mechanism allows for wide discretion in resource allocation, thus promoting the flourishing of several scheduling algorithms, with different purposes. It is therefore of great interest to compare the performance of such algorithms under different scenarios. Here, we carry out a thorough performance analysis of different scheduling algorithms for saturated User Datagram Protocol (UDP) and Transmission Control Protocol (TCP) traffic sources, as well as consider both the time- and frequency-domain versions of the schedulers and for both flat and frequency-selective channels. The analysis makes it possible to appreciate the difference among the scheduling algorithms and to assess the performance gain, in terms of cell capacity, users' fairness, and packet service time, obtained by exploiting the richer, but heavier, information carried by subchannel CQI. An important part of this analysis is a throughput guarantee scheduler, which we propose in this paper. The analysis reveals that the proposed scheduler provides a good tradeoff between cell capacity and fairness both for TCP and UDP traffic sources
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