A Channel State Information Feedback Method for Massive MIMO-OFDM

Kudo, Riichi,Armour, Simon M.D.,McGeehan, Joe P.,Mizoguchi, Masato The Korea Institute of Information and Commucation 2013 Journal of communications and networks Vol.15 No.4

Combining multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) with a massive number of transmit antennas (massive MIMO-OFDM) is an attractive way of increasing the spectrum efficiency or reducing the transmission energy per bit. The effectiveness of Massive MIMO-OFDM is strongly affected by the channel state information (CSI) estimation method used. The overheads of training frame transmission and CSI feedback decrease multiple access channel (MAC) efficiency and increase the CSI estimation cost at a user station (STA). This paper proposes a CSI estimation scheme that reduces the training frame length by using a novel pilot design and a novel unitary matrix feedback method. The proposed pilot design and unitary matrix feedback enable the access point (AP) to estimate the CSI of the signal space of all transmit antennas using a small number of training frames. Simulations in an IEEE 802.11n channel verify the attractive transmission performance of the proposed methods.

The Evolution of a Community of Practice for Physical Education

( Keejoon Yoon ),( Kathleen Armour ) 한국체육학회 2016 국제스포츠과학 학술대회 Vol.2016 No.1

Purpose: There is a widespread agreement that teachers’ continuing professional development (CPD) is important in teaching quality. A Community of Practice (CoP) approach has been proposed as an alternative to traditional types of CPD. Despite claims about the effectiveness of CoPs, there has been little research that reveals the complex pathways of learning from CoP to teachers’ practice (O’Sullivan, 2007). Method: The CoP investigated was not based in a single school, but was structured to draw teachers together from several schools. 8 secondary school PE teachers and a professor participated in the PE-CoP in South Korea. Data were collected from in-depth qualitative data using individual interviews with the teachers and the professor, a focus group with the teachers, and observations of PE classes and the CoP meetings. A constructivist revision of grounded theory (Charmaz, 2014) was used for data analysis using NVivo10. Result: There have been changes over time in the ways in which professional learning is supported in the CoP. In the early phase, teachers developed teaching ideas together and applied them to each teacher’s pedagogy. Following this, as new teachers joined existing members supported them in a manner that is characteristic of CoPs. More recently, however, the CoP has lost something of its social constructivist and collaborative focus on pedagogy. A range of reasons . internal and external . are explored. Conclusion: Studying the evolution of a CoP over time illustrates the importance of maintaining the original features of a CoP as proposed by Lave and Wenger (1991) and the challenges of so doing.

A Channel State Information Feedback Method for Massive MIMO-OFDM

Riichi Kudo,Simon M. D. Armour,Joe P. McGeehan,Masato Mizoguchi 한국통신학회 2013 Journal of communications and networks Vol.15 No.4

Combining multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) with a massive number of transmit antennas (massive MIMO-OFDM) is an attractive way of increasing the spectrum efficiency or reducing the transmission energy per bit. The effectiveness of Massive MIMOOFDM is strongly affected by the channel state information (CSI)estimation method used. The overheads of training frame transmission and CSI feedback decrease multiple access channel (MAC)efficiency and increase the CSI estimation cost at a user station (STA). This paper proposes a CSI estimation scheme that reduces the training frame length by using a novel pilot design and a novel unitary matrix feedback method. The proposed pilot design and unitary matrix feedback enable the access point (AP) to estimate the CSI of the signal space of all transmit antennas using a small number of training frames. Simulations in an IEEE 802.11n channel verify the attractive transmission performance of the proposed methods.

MIMO Techniques for Green Radio Guaranteeing QoS

Nicolaou, Marios,Han, Congzheng,Beh, Kian Chung,Armour, Simon,Doufexi, Angela The Korea Institute of Information and Commucation 2010 Journal of communications and networks Vol.12 No.2

Environmental issues and the need to reduce energy consumption for lowering operating costs have pushed power efficiency to become one of the major issues of current research in the field of wireless networks. This paper addresses a number of multiple input multiple output (MIMO) precoding and scheduling techniques across the PHY and MAC layers that can operate under a reduced link budget and collectively improve the transmit power efficiency of a base station, while maintaining the same levels of service. Different MIMO transmission and precoding schemes proposed for LTE, achieving varying degrees of multiuser diversity in both the time, frequency as well as the space domain, are examined. Several fairness-aware resource allocation algorithms are applied to the considered MIMO schemes and a detailed analysis of the tradeoffs between power efficiency and quality of service is presented. This paper explicitly examines the performance of a system serving real-time, VoIP traffic under different traffic loading conditions and transmit power levels. It is demonstrated that by use of efficient scheduling and resource allocation techniques significant savings in terms of consumed energy can be achieved, without compromising QoS.

Polar amplification dominated by local forcing and feedbacks

Stuecker, Malte F.,Bitz, Cecilia M.,Armour, Kyle C.,Proistosescu, Cristian,Kang, Sarah M.,Xie, Shang-Ping,Kim, Doyeon,McGregor, Shayne,Zhang, Wenjun,Zhao, Sen,Cai, Wenju,Dong, Yue,Jin, Fei-Fei Nature Publishing Group 2018 Nature climate change Vol.8 No.12

Acupuncture for endometriosis: A systematic review and meta-analysis

Nora Giese,Ki Kyung Kwon,Mike Armour 한국한의학연구원 2023 Integrative Medicine Research Vol.12 No.4

Background: Current endometriosis treatments do not always provide symptom relief, with many using complementary approaches. This study examined the effectiveness of acupuncture on pain and quality of life in people with endometriosis. Methods: Searches were conducted on Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, Allied and Complementary Medicine Database (AMED) and Embase (Ovid), Epistemonikos, and Cumulative Index to Nursing and Allied Health Literature (CINAHL; EBSCOhost) on 20 March 2023. Trials were included if they used penetrating acupuncture. Risk of bias was assessed with Cochrane RoB2 and GRADE for overall evidence certainty. Random-effects meta-analyses were undertaken, using Hedges’ g or mean difference (MD) both with 95 % confidence intervals (CI). Results: Six studies involving a total of 331 participants were included. Evidence for benefit was found for acupuncture compared to non-specific acupuncture on overall pelvic pain (g = 1.54, 95 % CI 0.92 to 2.16, 3 RCTs, n = 231, low certainty evidence, p<0.001), menstrual pain (g = 1.67, 95 % CI 1.23 to 2.12, 1 RCT, n = 106, moderate certainty evidence, p<0.001), and non-specified pelvic pain (MD -2.77, 95 % CI 2.15 to 3.38, 2 RCTs, n = 125, low certainty evidence, p<0.001), and compared to usual care on menstrual pain (g = 0.9, 95 % CI 0.15 to 1.64, 1 RCT, n = 19, very low certainty evidence, p = 0.02). Most studies reported low rates of adverse events. Conclusion: Acupuncture treatment for endometriosis demonstrated clinically relevant improvements in pelvic pain and should be considered as a potential treatment intervention. Study registration: PROSPERO ID: CRD42023408700.

MIMO Techniques for Green Radio Guaranteeing QoS

Marios Nicolaou,Congzheng Han,Kian Chung Beh,Simon Armour,Angela Doufexi 한국통신학회 2010 Journal of communications and networks Vol.12 No.2

Environmental issues and the need to reduce energy consumption for lowering operating costs have pushed power efficiency to become one of the major issues of current research in the field of wireless networks. This paper addresses a number of multiple input multiple output (MIMO) precoding and scheduling techniques across the PHY and MAC layers that can operate under a reduced link budget and collectively improve the transmit power efficiency of a base station, while maintaining the same levels of service. Different MIMO transmission and precoding schemes proposed for LTE, achieving varying degrees of multiuser diversity in both the time, frequency as well as the space domain, are examined. Several fairness-aware resource allocation algorithms are applied to the considered MIMO schemes and a detailed analysis of the tradeoffs between power efficiency and quality of service is presented. This paper explicitly examines the performance of a system serving real-time, VoIP traffic under different traffic loading conditions and transmit power levels. It is demonstrated that by use of efficient scheduling and resource allocation techniques significant savings in terms of consumed energy can be achieved, without compromising QoS.

Polar amplification dominated by local forcing and feedbacks

Malte F. Stuecker,Cecilia M. Bitz,Kyle C. Armour,Cristian Proistosescu,Sarah M. Kang,Shang-Ping Xie,Doyeon Kim,Shayne McGregor,Wenjun Zhang,Sen Zhao,Wenju Cai,Yue Dong,Fei-Fei Jin 한국기상학회 2018 한국기상학회 학술대회 논문집 Vol.2018 No.10