scholarly journals Fundamental Tradeoff Between Doppler Diversity and Channel Estimation Errors in SIMO High Mobility Communication Systems

IEEE Access ◽  
2018 ◽  
Vol 6 ◽  
pp. 21867-21878 ◽  
Author(s):  
Mahamuda Alhaji Mahamadu ◽  
Jingxian Wu ◽  
Zheng Ma ◽  
Weixi Zhou ◽  
Youhua Tang ◽  
...  
Keyword(s):  
Channel Estimation ◽  
Communication Systems ◽  
High Mobility ◽  
Estimation Errors ◽  
Channel Estimation Errors ◽  
Doppler Diversity

scholarly journals Uplink Non-Orthogonal Multiple Access with Channel Estimation Errors for Internet of Things Applications

Sensors ◽  
2019 ◽  
Vol 19 (4) ◽  
pp. 912
Author(s):  
Minjoong Rim ◽  
Chung Kang
Keyword(s):  
Internet Of Things ◽  
Channel Estimation ◽  
Communication Systems ◽  
Multiple Access ◽  
Base Station ◽  
Shared Resources ◽  
Estimation Errors ◽  
Channel Estimation Errors ◽  
Pilot Symbols ◽  
Shift Keying

One of the key requirements for next generation wireless or cellular communication systems is to efficiently support a large number of connections for Internet of Things (IoT) applications, and uplink non-orthogonal multiple access (NOMA) schemes can be used for this purpose. In uplink NOMA systems, pilot symbols, as well as data symbols can be superimposed onto shared resources. The error rate performance can be severely degraded due to channel estimation errors, especially when the number of superimposed packets is large. In this paper, we discuss uplink NOMA schemes with channel estimation errors, assuming that quadrature phase shift keying (QPSK) modulation is used. When pilot signals are superimposed onto the shared resources and a large number of devices perform random accesses concurrently to a single resource of the base station, the channels might not be accurately estimated even in high SNR environments. In this paper, we propose an uplink NOMA scheme, which can alleviate the performance degradation due to channel estimation errors.

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