(04) CTS - Communication Theory Symposium

Fundamentals and Optimization of Cellular Networks

Downlink Cellular Network Analysis with a Dual-slope Path Loss Model: Xinchen Zhang (The University of Texas at Austin & Qualcomm Inc., USA); Jeffrey Andrews (The University of Texas at Austin, USA)

pp. 5587-5592
Performance Analysis of Pair-wise Dynamic Multi-User Joint Transmission: Jeonghun Park, Namyoon Lee and Robert Heath (The University of Texas at Austin, USA)

pp. 5593-5598
Distributed Optimization of Multi-Cell Uplink Co-operation with Backhaul Constraints: Shirish Nagaraj (Nokia Networks, USA); Michael Honig (Northwestern University, USA); Khalid Zeineddine (Northwestern University & Nokia Networks, USA)

pp. 5599-5604
Outage Performance of Uplink Two-tier Networks Under Backhaul Constraint: Shirin Jalali (Princeton University, USA); Zolfa Zeinalpour (Yazd University, Iran); H. Vincent Poor (Princeton University, USA)

pp. 5605-5610
Delay-Optimal Fronthaul Allocation via Perturbation Analysis in Cloud Radio Access Networks: Wei Wang (Zhejiang University, P.R. China); Vincent Lau (Hong Kong University of Science and Technology, Hong Kong); Mugen Peng (Beijing University of posts & Telecommunications, P.R. China)

pp. 5611-5616
Delay Minimizing User Association in Cellular Networks via Hierarchically Well-Separated Trees: Jeffrey Wildman, Yusuf Osmanlioglu, Steven Weber and Shokoufandeh (Drexel University, USA)

pp. 5617-5623

Channel Capacity

High-SNR Capacity of Multiple-Antenna Phase-Noise Channels with Common/Separate RF Oscillators: M. Reza Khanzadi, Giuseppe Durisi and Thomas Eriksson (Chalmers University of Technology, Sweden)

pp. 5624-5629
Approximating the Constellation Constrained Capacity of the MIMO Channel with Discrete Input: Metodi Yankov (Technical University of Denmark, Denmark); Lars P. B. Christensen (Fingerprint Cards, Denmark); Knud Larsen and Soren Forchhammer (Technical University of Denmark, Denmark)

pp. 5630-5635
Delay-Limited Capacity of Fading Multiple Access and Broadcast Channels in the Low Power Regime: Zouheir Rezki (King Abdullah University of Science and Technologie (KAUST), Saudi Arabia); Mohamed-Slim Alouini (King Abdullah University of Science and Technology (KAUST), Saudi Arabia)

pp. 5636-5641
On the Capacity of Vector Gaussian Channels With Bounded Inputs: Borzoo Rassouli (Imperial College London, United Kingdom); Bruno Clerckx (Imperial College London & Korea University, United Kingdom)

pp. 5642-5647
On Achievable Rates for Analog Computing Real-Valued Functions Over the Wireless Channel: Mario Goldenbaum (Technische Universität Berlin, Germany); Slawomir Stanczak (Fraunhofer Heinrich Hertz Institute & Technische Universität Berlin, Germany); Holger Boche (Technical University Munich, Germany)

pp. 5648-5653
Capacity-Achieving Distributions of Impulsive Ambient Noise Channels: Hung Vu (McGill University, Canada); Nghi H Tran (University of Akron, USA); M. Cenk Gursoy (Syracuse University, USA); Tho Le-Ngoc (McGill University, Canada); Subramaniya Hariharan (University of Akron, USA)

pp. 5654-5659

Coding Theory

Protograph-Based Anytime Reliable Channel Coding Design: Nan Zhang and Md Noor-A-Rahim (University of South Australia, Australia); Badri N Vellambi (New Jersey Institute of Technology, USA); Khoa D. Nguyen (University of South Australia, Australia)

pp. 5660-5665
Anytime Reliable Bilayer Codes with Uncoded Relaying: Md Noor-A-Rahim, Khoa D. Nguyen and Gottfried Lechner (University of South Australia, Australia)

pp. 5666-5671
Non-binary Classical Error-correcting Codes for Quantum Communication: Christopher Boyd, Renaud-Alexandre Pitaval, Ulo Parts and Olav Tirkkonen (Aalto University, Finland)

pp. 5672-5677
Error Correcting Functional Source Coding with Decoder Side Information using Row-Latin Rectangles: Anindya Gupta and B. Sundar Rajan (Indian Institute of Science, India)

pp. 5678-5683
Low Error-Floor Majority-Logic Decoding Based Algorithm for Non-Binary LDPC Codes: Liyuan Song and Mu Zhang (Beihang University, P.R. China); Qin Huang (Beihang University, Beijing, P.R. China); Zulin Wang (Beihang University, P.R. China)

pp. 5684-5688
Improved Bit Error Rate Performance of Convolutional Codes with Synchronization Errors: Victor Buttigieg and Noel Farrugia (University of Malta, Malta)

pp. 5689-5694

Estimation and Detection

Distributed LMMSE Estimation in Cooperative Cellular Networks: Rajitha Senanayake and Phee Lep Yeoh (University of Melbourne, Australia); Jamie Evans (Monash University, Australia)

pp. 5695-5700
Optimizing Pilot Length for a Go/No-Go Decision in Two-State Block Fading Channels with Feedback: Chung-Yu Lou, Babak Daneshrad and Richard Wesel (University of California, Los Angeles, USA)

pp. 5701-5706
Segment Training Based Channel Estimation and Training Design in Cloud Radio Access Networks: Qiang Hu and Mugen Peng (Beijing University of posts & Telecommunications, P.R. China); Xinqian Xie (Beijing University of Posts and Telecommunications, P.R. China); Feifei Gao (Tsinghua University, P.R. China); Dongming Wang (Southeast University & National Mobile Communications Research Lab., P.R. China)

pp. 5707-5712
On the Age of Channel Information for a Finite-State Markov Model: Maice Costa (University of Maryland at College Park, USA); Stefan Valentin (Huawei Technologies, France); Anthony Ephremides (University of Maryland at College Park, USA)

pp. 5713-5718
Delay Constrained Linear Transmission of a Mixture of Gaussian Measurements over a Fading Channel: Onur Tan (Centre Tecnològic de Telecomunicacions de Catalunya (CTTC), Spain); Deniz Gündüz (Imperial College London, United Kingdom); Jesús Gómez-Vilardebò (CTTC, Spain)

pp. 5719-5724

Interference Management and Power Control

Topological Interference Management with just Retransmission: What are the "Best" Topologies?: Navid NaderiAlizadeh, Aly El Gamal and Salman Avestimehr (University of Southern California, USA)

pp. 5725-5731
Interference Shaping for Device-to-Device Communication in Cellular Networks: Michael Newinger, Andreas Dotzler and Wolfgang Utschick (Technische Universität München, Germany)

pp. 5732-5737
Joint Interference Alignment and Bi-Directional Scheduling for MIMO Two-Way Multi-Link Networks: Ali Mohammad Fouladgar and Osvaldo Simeone (New Jersey Institute of Technology, USA); Onur Sahin (InterDigital, Inc., USA); Petar Popovski (Aalborg University, Denmark); Shlomo (Shitz) Shamai (The Technion, Israel)

pp. 5738-5743
Best-Response Team Power Control for the Interference Channel with Local CSI: Paul de Kerret (EURECOM, France); Samson E Lasaulce (CNRS - Supelec, France); David Gesbert (Eurecom Institute, France); Umer Salim (Intel Mobile Communications, France)

pp. 5744-5748
Uplink Performance of Large Optimum-Combining Antenna Arrays in Power-Controlled Cellular Networks: Siddhartan Govindasamy (F. W. Olin College of Engineering, USA)

pp. 5749-5755
Retrospective Interference Alignment for Two-Cell Uplink MIMO Cellular Networks with Delayed CSIT: Wonjae Shin, Yonghee Han and Jungwoo Lee (Seoul National University, Korea); Namyoon Lee and Robert Heath (The University of Texas at Austin, USA)

pp. 5756-5762

Physical-Layer Security

On Secret-Key Generation Using Wideband Channels in Mobile Networks: Yuan Shen (Tsinghua University & Massachusetts Institute of Technology, P.R. China); Moe Win (Massachusetts Institute of Technology, USA)

pp. 5763-5768
Secrecy for MISO Broadcast Channels via Alternating CSIT: Pritam Mukherjee (University of Maryland, USA); Ravi Tandon (Virginia Tech, USA); Sennur Ulukus (University of Maryland, USA)

pp. 5769-5774
On the Continuity of the Secrecy Capacity of Wiretap Channels Under Channel Uncertainty: Holger Boche (Technical University Munich, Germany); Rafael F. Schaefer and H. Vincent Poor (Princeton University, USA)

pp. 5775-5780
Secure Degrees of Freedom of N × N × M Wiretap Channel with a K-Antenna Cooperative Jammer: Mohamed Nafea (The Pennsylvania State University, USA); Aylin Yener (Pennsylvania State University, USA)

pp. 5781-5786
Unshared Secret Key Cryptography: Finite Constellation Inputs and Ideal Secrecy Outage: Shuiyin Liu, Yi Hong and Emanuele Viterbo (Monash University, Australia)

pp. 5787-5792
The Individual Secrecy Capacity of Degraded Multi-Receiver Wiretap Broadcast Channels: Ahmed Mansour (Technische Universität München, Germany); Rafael F. Schaefer (Princeton University, USA); Holger Boche (Technical University Munich, Germany)

pp. 5793-5798

Network Information Theory

Three-User MISO Broadcast Channel: How Much Can CSIT Heterogeneity Help?: Sina Lashgari (Cornell University, USA); Ravi Tandon (Virginia Tech, USA); Salman Avestimehr (University of Southern California, USA)

pp. 5799-5804
An Achievable Rate Region of Broadcast Relay Channel with State Feedback: Chao He (SUPELEC, France); Sheng Yang (Supélec, France); Pablo Piantanida (SUPELEC, France)

pp. 5805-5810
DoF Analysis of the K-user MISO Broadcast Channel with Hybrid CSIT: Borzoo Rassouli (Imperial College London, United Kingdom); Bruno Clerckx (Imperial College London & Korea University, United Kingdom); Chenxi Hao (Imperial College London, United Kingdom)

pp. 5811-5816
On User Scheduling for Maximum Throughput in K-user MISO Broadcast Channels: Martina Cardone (Eurecom, France); Daniela Tuninetti (University of Illinois at Chicago, USA); Raymond Knopp (Institut Eurecom, France)

pp. 5817-5822
Deterministic IMAC Revisited: Constant-Gap Capacity in the Weak Interference Case: Rick Fritschek (Berlin Institute of Technology, Germany); Gerhard Wunder (Heinrich-Hertz-Institut, Germany)

pp. 5823-5828
Degrees-of-Freedom of the K-User MISO Interference Channel with Delayed Local CSIT: Chenxi Hao (Imperial College London, United Kingdom); Bruno Clerckx (Imperial College London & Korea University, United Kingdom)

pp. 5829-5834

Energy Constrained Communications

An Adaptive Transmission Protocol for Wireless-Powered Cooperative Communications: Yifan Gu and He Chen (The University of Sydney, Australia); Yonghui Li (University of Sydney, Australia); Branka Vucetic (The University of Sydney, Australia)

pp. 5835-5840
Multi-Sensor Estimation Using Energy Harvesting and Energy Sharing: Steffi Knorn, Subhrakanti Dey and Anders Ahlen (Uppsala University, Sweden); Daniel E Quevedo (The University of Newcastle, Australia)

pp. 5841-5846
Capacity Region of MISO Broadcast Channel with SWIPT: Shixin Luo (National University of Singapore, Singapore); Jie Xu (Singapore University of Technology and Design, Singapore); Teng Joon Lim and Rui Zhang (National University of Singapore, Singapore)

pp. 5847-5852
Optimal Packet Scheduling for Delay Minimization in an Energy Harvesting System: Tian Tong (Tsinghua University, P.R. China); Sennur Ulukus (University of Maryland, USA); Wei Chen (Tsinghua University, P.R. China)

pp. 5853-5858
Nonlinear Code Design for Joint Energy and Information Transfer: Mehdi Dabirnia (Bilkent University, Turkey); Tolga M. Duman (Bilkent University & Arizona State University (ON LEAVE), Turkey)

pp. 5859-5864
Improving the Throughput of Wireless Powered Dual-hop Systems with Full Duplex Relaying: Caijun Zhong (Zhejiang University, P.R. China); Himal A Suraweera (University of Peradeniya, Sri Lanka); Gan Zheng (University of Essex & University of Luxembourg, United Kingdom); Ioannis Krikidis (University of Cyprus, Cyprus); Zhaoyang Zhang (Zhejiang University, P.R. China)

pp. 5865-5870

Performance Analysis Techniques

A Fast Simulation Method for the Log-Normal Sum Distribution Using a Hazard Rate Twisting Technique: Nadhir Ben Rached (King Abdullah University of Science and Technology, Saudi Arabia); Fatma Benkhelifa (King Abdullah University of Science and Technology, Tunisia); Mohamed-Slim Alouini (King Abdullah University of Science and Technology (KAUST), Saudi Arabia); Raul Tempone (King Abdullah University of Science and Technology, Saudi Arabia)

pp. 5871-5876
Numerically Efficient Generation of Exponentially Correlated Two-Dimensional Shadowing: Tariq M Ali (University of Texas at Dallas, USA); Mohammad Saquib (UniversityTexas Dallas, USA)

pp. 5877-5883
Bit Error Rate Analysis of Convolutionally Coded BICM with Specific Interleaver Structures: Yuta Hori and Hideki Ochiai (Yokohama National University, Japan)

pp. 5884-5889
MGF Approach to the Capacity Analysis of Generalized Two-Ray Fading Models: Milind Rao (Stanford University, USA); Francisco Javier Lopez-Martinez (Universidad de Malaga, Spain); Mohamed-Slim Alouini (King Abdullah University of Science and Technology (KAUST), Saudi Arabia); Andrea Goldsmith (Stanford University, USA)

pp. 5890-5896
On The Statistics of SINR in Cellular Networks: Arman Shojaeifard and Khairi A. Hamdi (University of Manchester, United Kingdom); Emad Alsusa (Manchester University, United Kingdom); Daniel K. C. So and Jie Tang (University of Manchester, United Kingdom)

pp. 5897-5902

PHY-Layer Advances in Communications I

MUDRI: A Fault-Tolerant Decoding Algorithm: Predrag N. Ivanis and Omran Rasheed (School of Electrical Engineering, University of Belgrade, Serbia); Bane Vasić (University of Arizona, USA)

pp. 5903-5908
Semiconductor Optical Amplifier-Assisted Optical Wireless Links: The Effect of Noise and Turbulence: Konstantinos Yiannopoulos, Nikos C. Sagias and Anthony Boucouvalas (University of Peloponnese, Greece)

pp. 5909-5914
Self-Coherent OFDM for Wireless Communications: Qianyu Jin, Yi Hong and Emanuele Viterbo (Monash University, Australia)

pp. 5915-5920
Secure D2D Communication in Large-Scale Cognitive Cellular Networks with Wireless Power Transfer: Yuanwei Liu (Queen Mary, University of London, United Kingdom); Lifeng Wang (University College London, United Kingdom); Syed Ali Raza Zaidi (University of Leeds, United Kingdom); Maged Elkashlan (Queen Mary, University of London, United Kingdom); Trung Q. Duong (Queen's University Belfast, United Kingdom)

pp. 5921-5926
Secure encoder designs based on turbo codes: Alexandros Katsiotis (National and Kapodistrian University of Athens, Greece); Nicholas Kolokotronis (University of Peloponnese, Greece); Nicholas Kalouptsidis (National and Kapodistrian University of Athens, Greece)

pp. 5927-5932

MIMO and Massive MIMO

Optimized MIMO Transmission and Compression for Interference Mitigation with Cooperative Relay: Seyedarvin Ayoughi and Wei Yu (University of Toronto, Canada)

pp. 5933-5938
On Capacity of Two-Way Massive MIMO Full-Duplex Relay Systems: Zhanzhan Zhang, Zhiyong Chen, Manyuan Shen and Bin Xia (Shanghai Jiao Tong University, P.R. China)

pp. 5939-5944
High Frequency Differential MIMO: Basic Theory and Transceiver Architectures: Akbar Sayeed and John Brady (University of Wisconsin-Madison, USA)

pp. 5945-5950
Error Probability Minimization for MIMO Systems with Imperfect Channel State Information: Hieu Duy Nguyen (Institute for Infocomm Research (I2R), The Agency for Science, Technology and Research (ASTAR), Singapore); Boon Sim Thian and Sumei Sun (Institute for Infocomm Research, Singapore)

pp. 5951-5956
Spectral Efficiency of Massive MIMO Systems with D2D Underlay: Xingqin Lin (Ericsson Research, USA); Robert Heath and Jeffrey Andrews (The University of Texas at Austin, USA)

pp. 5957-5962
Optimal Signaling of MISO Full-Duplex Two-Way Wireless Channel: Shuqiao Jia and Behnaam Aazhang (Rice University, USA)

pp. 5963-5968

Cooperative and Relay Communications

Secrecy in the Two-Way Untrusted Relay Channel with Compute-and-Forward: Johannes Richter (Dresden University of Technology, Germany); Christian Scheunert (TU Dresden, Germany); Sabrina Engelmann (Dresden University of Technology, Germany); Eduard Jorswieck (TU Dresden, Germany)

pp. 5969-5974
On the Optimality of Network Coding in Two-Way Decode-and-Forward MIMO Relay Channel: Jianjun Peng and Wei Chen (Tsinghua University, P.R. China)

pp. 5975-5979
Diversity-Multiplexing Tradeoff for Network Coded Cooperative OFDMA Systems: Ali Reza Heidarpour (Ozyegin University, Turkey); Gunes Karabulut Kurt (Istanbul Technical University, Turkey); Murat Uysal (Ozyegin University, Turkey)

pp. 5980-5985
Distributed MIMO Multiway Relaying: Joint Signal Alignment and Interference Neutralization: Rui Wang (Tongji University, P.R. China); Xiaojun Yuan (ShanghaiTech University, P.R. China); Raymond W. Yeung (The Chinese University of Hong Kong, Hong Kong)

pp. 5986-5991
Cooperative Communication for High-Reliability Low-Latency Wireless Control: Vasuki Narasimha Swamy, Sahaana Suri and Paul Rigge (University of California, Berkeley, USA); Matthew Weiner (University of California at Berkeley, USA); Gireeja Ranade (University of California, Berkeley, USA); Anant Sahai and Borivoje Nikolić (UC Berkeley, USA)

pp. 5992-5998
Communications Using Ubiquitous Antennas: Free-Space Propagation: Kaibin Huang (Dept. of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong); Jiayi Chen (Shenzhen University, P.R. China); Vincent Lau (Hong Kong University of Science and Technology, Hong Kong)

pp. 5999-6005

Source and Channel Coding

On Locally Decodable Source Coding: Ali Makhdoumi (MIT, USA); Shao-Lun Huang (Massachusetts Institute of Technology, USA); Muriel Médard and Yury Polyanskiy (MIT, USA)

pp. 6006-6011
Zero-Delay Joint Source-Channel Coding in the Presence of Interference Known at the Encoder: Morteza Varasteh (Imperial College, United Kingdom); Deniz Gündüz (Imperial College London, United Kingdom); Ertem Tuncel (UC Riverside, USA)

pp. 6012-6017
Joint Binary Field Transform and Polar Coding: Mohammad Sadegh Mohammadi (Aarhus University & Macquary University, Denmark); Qi Zhang (Aarhus University, Denmark); Eryk Dutkiewicz (Macquarie University, Australia)

pp. 6018-6023
Construction of Protographs for Large-Girth Structured LDPC Convolutional Codes: Junho Cho (Bell Labs, Alcatel-Lucent, USA); Laurent Schmalen (Alcatel-Lucent, Bell Laboratories, Germany)

pp. 6024-6029
Oblivious Lattice Codes for Gaussian Relay Channels: Arash Behboodi (RWTH Aachen University, Germany)

pp. 6030-6035
Identifying Block Codes using Groebner Bases: Saravanan Vijayakumaran (IIT Bombay, India)

pp. 6036-6042

PHY-Layer Advances in Communications II

On the Maximum Doppler Diversity of High Mobility Systems with Imperfect Channel State Information: Weixi Zhou (Southwest Jiaotong University, P.R. China); Jingxian Wu (University of Arkansas, USA); Pingzhi Fan (Southwest Jiaotong Universityiversity, P.R. China)

pp. 6043-6048
A Necessary and Sufficient Closure Property for Two-Stage Constructions of Switching Networks: Ching-Min Lien, Cheng-Shang Chang and Duan-Shin Lee (National Tsing Hua University, Taiwan)

pp. 6049-6054
Channel Feedback Reduction for Wireless Multimedia Broadcast Multicast Service Systems: Yu-Yun Chang, Wei-Shun Liao, Jin-Hao Li and Hsuan-Jung Su (National Taiwan University, Taiwan)

pp. 6055-6059
Noncoherent Composite Hypothesis Testing Receivers for Extended Range Bistatic Scatter Radio WSNs: Panos N. Alevizos and Aggelos Bletsas (Technical University of Crete, Greece)

pp. 6060-6065
Protograph-Based LDPC Convolutional Codes for Continuous Phase Modulation: Tarik Benaddi (IRIT & CNES, France); Charly Poulliat (INP - ENSEEIHT Toulouse, France); Marie-Laure Boucheret (University of Toulouse IRIT Enseeiht, France); Benjamin Gadat (Thales Alenia Space, France); Guy Lesthievent (CNES, France)

pp. 6066-6072

Network-Layer Advances for Communications

On the Synergistic Benefits of Alternating CSIT for X Channel within a Four-symbol Channel Extension: Ahmed Wagdy Shaban (Qatar University & Wireless Intelligent Networks Center, Nile University, Qatar); Amr El-Keyi (Nile University, Egypt); Tamer Khattab (Qatar University, Qatar); Mohammed Nafie (Cairo University & Nile University, Egypt)

pp. 6073-6079
Secure Green Communication for Amplify-and-Forward Relaying with Eavesdroppers: Dong Wang, Bo Bai and Wei Chen (Tsinghua University, P.R. China); Zhu Han (University of Houston, USA)

pp. 6080-6085
On the Push-based Converged Network with Limited Storage: Hao Feng (Shanghai Jiao Tong Univerisity, P.R. China); Zhiyong Chen (Shanghai Jiao Tong University, P.R. China); Hui Liu (Shanghai JiaoTong University, P.R. China)

pp. 6086-6091
Diversity-Security Tradeoff for Compound Channels: Joseph Jean Boutros and Volkan Dedeoglu (Texas A&M University at Qatar, Qatar)

pp. 6092-6097
Distributed Algorithm for Nonconvex Power Optimization: Achieving Global Weighted Sum-Rate Maximum: Haiyou Guo (Bell Labs China, R&I, Alcatel-Lucent Shanghai Bell, Shanghai, China, P.R. China); Shuqin Li (Bell Labs China, Alcatel-Lucent Shanghai Bell Co., Ltd., Hong Kong); Liyu Cai (Alcatel-Lucent Shanghai Bell Co., Ltd, P.R. China)

pp. 6098-6103

Network Coding

Optimization-Based Linear Network Coding for General Connections of Continuous Flows: Ying Cui (Shanghai Jiaotong University, P.R. China); Muriel Médard (MIT, USA); Edmund Yeh (Northeastern University, USA); Douglas Leith (Trinity College Dublin, Ireland); Ken R. Duffy (National University of Ireland Maynooth, Ireland)

pp. 6104-6110
Binary Systematic Network Coding for Progressive Packet Decoding: Andrew L. Jones, Ioannis Chatzigeorgiou and Andrea Tassi (Lancaster University, United Kingdom)

pp. 6111-6116
Composite Extension Finite Fields for Low Overhead Network Coding: Telescopic Codes: Janus Heide (Steinwurf, Denmark); Daniel E. Lucani (Aalborg University, Denmark)

pp. 6117-6122
On Vector Linear Solvability of Multicast Networks: Qifu T Sun (University of Science and Technology Beijing, P.R. China); Xiaolong Yang (University of Science & Technology Beijing, P.R. China); Keping Long (University of Science and Technology Beijing, P.R. China); Xunrui Yin and Zongpeng Li (University of Calgary, Canada)

pp. 6123-6129
Network Reduction for Coded Multiple-hop Networks: Jinfeng Du, Naomi Sweeting, David Adams and Muriel Médard (MIT, USA)

pp. 6130-6135
Performance Analysis of Queueing Systems with Systematic Packet-Level Coding: Giuseppe Cocco and Tomaso De Cola (German Aerospace Center (DLR), Germany); Matteo Berioli (TriaGnoSys GmbH & Zodiac Aerospace, Germany)

pp. 6136-6141