scholarly journals Multichannel simultaneous uplink and downlink transmission scheme for flexible duplexing

2017 ◽  
Vol 2017 (1) ◽  
Author(s):  
Adrian Kliks ◽  
Paweł Kryszkiewicz
Keyword(s):  
Transmission Scheme ◽  
Downlink Transmission

Performance analysis of LTE enterprise femtocell using cooperative downlink transmission scheme

ICTC 2011 ◽  
2011 ◽  
Author(s):  
Seung-Yeon Kim ◽  
Choong-Ho Cho ◽  
Hyong-Woo Lee ◽  
Nam-Hoon Park ◽  
Byung Han Ryu ◽  
...  
Keyword(s):  
Performance Analysis ◽  
Transmission Scheme ◽  
Downlink Transmission

scholarly journals Exploiting Spatial and Frequency Diversity in Spatially Correlated MU-MIMO Downlink Channels

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Rosdiadee Nordin
Keyword(s):  
Spatial Diversity ◽  
Base Station ◽  
Limiting Factors ◽  
Mimo Channel ◽  
Frequency Diversity ◽  
Transmission Scheme ◽  
Downlink Transmission ◽  
Spatially Correlated ◽  
Allocation Process ◽  
Downlink Channels

The effect of self-interference due to the increase of spatial correlation in a MIMO channel has become one of the limiting factors towards the implementation of future network downlink transmissions. This paper aims to reduce the effect of self-interference in a downlink multiuser- (MU-) MIMO transmission by exploiting the available spatial and frequency diversity. The subcarrier allocation scheme can exploit the frequency diversity to determine the self-interference from the ESINR metric, while the spatial diversity can be exploited by introducing the partial feedback scheme, which offers knowledge of the channel condition to the base station and further reduces the effect before the allocation process takes place. The results have shown that the proposed downlink transmission scheme offers robust bit error rate (BER) performance, even when simulated in a fully correlated channel, without imposing higher feedback requirements on the base controller.

scholarly journals Occupancy-balancing downlink transmission for enhancing scalability of LoRa networks

2020 ◽  
Vol 16 (12) ◽  
pp. 155014772097927
Author(s):  
Cheonyong Kim ◽  
Joobum Kim ◽  
Jaiseung Kwak ◽  
Kiwook Kim ◽  
Woojin Seok
Keyword(s):  
Spread Spectrum ◽  
Delivery Ratio ◽  
Transmission Power ◽  
Transmission Scheme ◽  
Medium Access ◽  
Downlink Transmission ◽  
Packet Delivery ◽  
Modulation Parameter ◽  
Simulation Results ◽  
The Internet Of Things

LoRa/LoRaWAN is growing rapidly as an underlying technology for the Internet of Things because of its long-range connectivity and low power. However, its limited scalability, owing to spread spectrum–based modulation and contention-based medium access control, impedes its use in emerging massive applications. In this study, we propose a downlink transmission scheme for enhancing the scalability of LoRa networks. The proposed scheme consists of two mechanisms. First, a modulation parameter is adjusted using the different transmission power limitations between the gateways and end devices to reduce downlink duration. Second, the timing of downlink traffic is selected based on uplink traffic concentration analysis. The proposed scheme reduces the uplink failure, and consequently, allows more end devices to participate in the network. The simulation results show that the proposed scheme is superior to the standard protocol in terms of the packet delivery ratio.

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