scholarly journals An Algorithm That Predicts CSI to Allocate Bandwidth for Healthcare Monitoring in Hospital's Waiting Rooms

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Di Lin ◽  
Fabrice Labeau
Keyword(s):  
System Performance ◽  
Bandwidth Allocation ◽  
Efficient Solution ◽  
Monitoring Systems ◽  
Central Unit ◽  
Imperfect Csi ◽  
Negative Effects ◽  
Channel State ◽  
State Information ◽  
Healthcare Monitoring

In wireless healthcare monitoring systems, bandwidth allocation is an efficient solution to the problem of scarce wireless bandwidth for the monitoring of patients. However, when the central unit cannot access the exact channel state information (CSI), the efficiency of bandwidth allocation decreases, and the system performance also decreases. In this paper, we propose an algorithm to reduce the negative effects of imperfect CSI on system performance. In this algorithm, the central unit can predict the current CSI by previous CSI when the current CSI is not available. We analyze the reliability of the proposed algorithm by deducing the standard error of estimated CSI with this algorithm. In addition, we analyze the efficiency of the proposed algorithm by discussing the system performance with this algorithm.

scholarly journals SVD-Aided Beamforming and Power Allocation Algorithm for Multiuser Turbo-BLAST System Uplink with Imperfect CSI

2012 ◽  
Vol 2012 ◽  
pp. 1-13
Author(s):  
Xiaomin Chen ◽  
Xiangbin Yu ◽  
Dazhuan Xu
Keyword(s):  
Power Allocation ◽  
System Performance ◽  
Estimation Error ◽  
Channel Estimation Error ◽  
Iterative Detection ◽  
Receiver Design ◽  
Imperfect Csi ◽  
Channel State ◽  
Multiuser Interference ◽  
State Information

The SVD-aided joint transmitter and receiver design for the uplink of CDMA-based synchronous multiuser Turbo-BLAST systems is proposed in the presence of channel state information (CSI) imperfection. At the transmitter, the beamforming and power allocation schemes are developed to maximize the capacity of the desired user. At the receiver, a suboptimal decorrelating scheme is first proposed to mitigate the multiuser interference (MUI) and decouple the detection of different users with imperfect CSI, and then the iterative detecting algorithm that takes the channel estimation error into account is designed to cancel the coantenna interference (CAI) and enhance the bit error rate (BER) results further. Simulation results show that the proposed uplink CDMA-based multiuser Turbo-BLAST model is effective, the detection from every user is completely independent to each other after decorrelating, and the system performance can be enhanced by the proposed beamforming and power allocation schemes. Furthermore, BER performance can be enhanced by the modified iterative detection. The effect of CSI imperfection is evaluated, which is proved to be a useful tool to assess the system performance with imperfect CSI.

scholarly journals A new look on CSI imperfection in downlink NOMA systems

2021 ◽  
Vol 10 (3) ◽  
pp. 1415-1422
Author(s):  
Anh-Tu Le ◽  
Dinh-Thuan Do
Keyword(s):  
Monte Carlo ◽  
Performance Analysis ◽  
System Performance ◽  
Multiple Access ◽  
Spectrum Efficiency ◽  
System Model ◽  
Full Duplex ◽  
Channel State ◽  
State Information ◽  
Cooperative Scheme

Observing that cooperative scheme benefits to non-orthogonal multiple access (NOMA) systems, we focus on system performance analysis of downlink. However, spectrum efficiency is still high priority to be addressed in existing systems and hence this paper presents full-duplex enabling in NOMA systems. Other challenge needs be considered related to channel state information (CSI). In particular, we derive closedform expressions of outage probability for such NOMA systems under the presence of CSI imperfection. Furthermore, to fully exploit practical environment, we provide system model associated with Nakagami-m fading. The Monte-Carlo simulations are conducted to verify the exactness of considered systems.

scholarly journals Performance Analysis of MEC Based on NOMA under Imperfect CSI with Eavesdropper

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Xuehua Li ◽  
Yingjie Pei ◽  
Huan Jiang ◽  
Xinwei Yue ◽  
Yafei Wang ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Channel State Information ◽  
Multiple Access ◽  
System Throughput ◽  
Secrecy Outage Probability ◽  
Imperfect Csi ◽  
Channel State ◽  
State Information ◽  
Secrecy Outage ◽  
The Impact

Mobile edge computing (MEC) is becoming more and more popular because of improving computing power in virtual reality, augmented reality, unmanned driving, and other fields. This paper investigates a nonorthogonal multiple access- (NOMA-) based MEC system, which is under imperfect channel state information (ipCSI). In this system model, a pair of users offloads their tasks to the MEC server with the existence of an eavesdropper (Eve). To evaluate the impact of Eve on the performance of the NOMA-MEC system, the secrecy outage probability (SOP) expressions for two users with the conditions of imperfect CSI and perfect channel state information (pCSI) are derived. In addition, both throughput and energy efficiency are discussed in the delay-limited transmission mode. Simulation results reveal that (1) due to the influence of channel estimation errors, the secrecy outage behaviors of two users under ipCSI conditions are worse than those of users with pCSI; (2) the secrecy performance of NOMA-MEC is superior to orthogonal multiple access- (OMA-) aided MEC systems; and (3) the NOMA-MEC systems have the ability to attain better system throughput and energy efficiency compared with OMA-MEC.

scholarly journals Asynchronous Two-Way Relaying Networks Using Distributed Differential Space-Time Coding

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Minjie Qian ◽  
Yanliang Jin ◽  
Zhuo Wu ◽  
Tao Wang
Keyword(s):  
Signal Detection ◽  
System Performance ◽  
Space Time ◽  
Channel State ◽  
Detection Scheme ◽  
State Information ◽  
Space Time Coding ◽  
Time Coding ◽  
Simulation Results ◽  
Synchronization Effect

A signal detection scheme is proposed for two-way relaying network (TWRN) using distributed differential space-time coding (DDSTC) under imperfect synchronization. Unlike most of existing work, which assumed perfect synchronization and channel state information (CSI) at all nodes, a more realistic scenario is investigated here by considering the signals transmitted from the two source nodes arriving at the relay not exactly at the same time due to the distributed nature of the nodes, and no CSI is available at any node. The proposed signal detection scheme is then demonstrated to remove the imperfect synchronization effect significantly through simulation results. Furthermore, pairwise error probability (PEP) of the asynchronous TWRN is analyzed and derived for both source nodes. Based on the simplified PEP expression, an optimum power allocation (OPA) scheme is then determined to further improve the whole system performance, when neither the source nor the relay has any knowledge of the CSI.

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