Ali Alwadi Collision Monitoring and Alarm in Ice-Hockey School of Electrical Engineering Thesis submitted for examination for the degree of Master of Science in Technology. Espoo 12.03.2014 Thesis supervisor: Prof. Riku Jäntti Thesis advisor: Prof. Riku Jäntti AALTO UNIVERSITY SCHOOL ABSTRACT OF THE OF SCIENCE AND TECHNOLOGY MASTER'S THESIS Author: Ali Mohsen Hasan Salman Alwadi Title: Collision Monitoring and Alarm in Ice-Hockey. Date: 12.03.2014 Language: English Number of pages: 9+64 Department: Department of Communications and Networking Professorship: Radio Communications Code: S-72 Supervisor: Prof. Riku Jäntti Advisor: Prof. Riku Jäntti Abstract: Full contact sports are inherently dangerous as they involve tough collisions between players. Wireless and sensing technologies have the potential to reduce the risk of severe injuries in athletes by alarming the harshness of each collision between players to a medical team that can deal with this issue instantly, instead of allowing this hit to develop to a serious injury. Ice-Hockey is used as the basis of the experiment in this Master Thesis, since it is the highest contributor to brain injuries in sports and a source of devastating chest injuries. In order to achieve the goal of proposing and evaluating a sport safety system that can monitor and alarm the collisions between players to a medical team, several important questions were put to define the road-map of the research. Initially, a survey on the state-of- the-art sport safety systems has been made. The result of this survey shows that there is only one commercially available system: Head Impact Telemetry (HIT). Then, based on the study of HIT and its related products, several justified system requirements have been listed. Add to that, the applicable wireless and sensing technologies were benchmarked against the developed system requirements. This benchmarking resulted in selecting accelerometers and Bluetooth Low Energy (BLE) for the proposed system. In addition, a theoretical evaluation was made to the proposed system to find the Bit Error Rate (BER), Packet Error Rate (PER), average packet transmissions, average packet delay and packet loss percentage in AWGN, Rayleigh and Rician channels. The system evaluation results show that the proposed system with limited transmissions performs better than the system with infinite transmission attempts in both cases: no interfering users and one interfering user, over the stated channels. The limited transmission attempts system gives lower packet delay and less number of packet retransmissions. However, this limited transmission attempts system introduces packet loss. Also, it has been observed that small packet size selection reduces the latency and transmission attempts. Therefore, this system offers the Ice-Hockey community with a cost-efficient and reliable solution to the players’ collisions monitoring and early diagnostic problem. Consequently, this may lead to reduction in total severe injuries and increased player career duration. Keywords: Ice-Hockey, BLE, Collision Monitoring, SFH-GMSK ii Preface First of all, I would like to express my gratitude and appreciation to Prof. Riku Jäntti for his guidance, patience, support and mentoring throughout the Master Thesis period. I also would like to thank all my friends for their joyous company during my Master studies. Moreover, I would like to thank my employer Bitville Oy for allowing me to have flexible working hours when required. Finally but most importantly, I would like to thank my family for their endless love, encouragement and support throughout my life. Otaniemi, 12.03.2014 Ali Alwadi iii Table of Contents Abstract..................................................................................................................................... ii Preface ..................................................................................................................................... iii List of Abbreviations ............................................................................................................... vi List of Symbols ....................................................................................................................... vii List of Figures........................................................................................................................ viii List of Tables ........................................................................................................................... ix 1 Introduction ..................................................................................................................... 1 1.1 Background and Motivation ............................................................................................ 1 1.2 Objectives and Related Research Questions ................................................................. 1 1.3 Contributions.................................................................................................................. 2 1.4 Thesis Outline ................................................................................................................ 2 2 Sport Safety Monitoring Preliminaries ........................................................................... 3 2.1 Scenario Description ...................................................................................................... 3 2.2 Head Impact Telemetry (HIT) System ............................................................................ 3 2.2.1 Riddell Sideline Response System (SRS) ............................................................... 4 2.2.2 Riddell InSite .......................................................................................................... 5 2.3 Proposed System Requirements .................................................................................... 7 2.3.1 Justification of System Requirements ..................................................................... 7 2.3.2 Summary of System Requirements......................................................................... 8 2.4 Applicable Wireless Technologies .................................................................................. 9 2.4.1 Bluetooth IEEE 802.15.1......................................................................................... 9 2.4.2 ZigBee IEEE 802.15.4 .......................................................................................... 13 2.4.3 Dash7 (ISO 18000-7)............................................................................................ 15 2.4.4 Summary .............................................................................................................. 16 2.5 Applicable Collision Detection Sensors ........................................................................ 16 2.5.1 Overview .............................................................................................................. 16 2.5.2 Accelerometer ...................................................................................................... 17 2.5.3 Force Sensing Resistor (FSR) .............................................................................. 17 2.5.4 Load Cell .............................................................................................................. 18 2.5.5 Summary and Comparison ................................................................................... 19 iv 3 Benchmarking the Applicable Wireless Technologies................................................ 20 3.1 Grading Methodology ................................................................................................... 20 3.2 Network Size ................................................................................................................ 21 3.3 Cost ............................................................................................................................. 21 3.4 Size.............................................................................................................................. 22 3.5 Throughput .................................................................................................................. 22 3.6 Simultaneous Monitoring Capability ............................................................................. 23 3.7 Communication Range ................................................................................................. 23 3.8 Coexistence Performance ............................................................................................ 24 3.9 Power Consumption ..................................................................................................... 26 3.10 Latency .................................................................................................................... 26 3.11 Summary and Overall Performance .......................................................................... 27 4 Evaluation of the Proposed System ............................................................................. 28 4.1 Proposed System Architecture ..................................................................................... 28 4.2 Channel Model ............................................................................................................. 28 4.3 Bit Error Rate (BER) of BLE ......................................................................................... 30 4.4 Packet Error Rate (PER) of BLE................................................................................... 34 4.5 Gilbert-Elliot Model ....................................................................................................... 34 4.6 Average Number of Transmission Attempts ................................................................. 35 4.6.1 MaxTransmit......................................................................................................... 35 4.6.2 MaxTransmit is set to Infinite ................................................................................ 35 4.6.3 MaxTransmit is set to 256 ..................................................................................... 36 4.7 Average Packet Delay.................................................................................................. 36 4.7.1 MaxTransmit is set to Infinite ................................................................................ 36 4.7.2 MaxTransmit is set to 256 ..................................................................................... 37 4.8 Packet Loss of BLE (MaxTransmit = 256) .................................................................... 37 5 System Results and Analysis ....................................................................................... 38 5.1 BER Results................................................................................................................. 38 5.2 PER Results................................................................................................................. 40 5.3 Average Packet Transmissions Results ....................................................................... 43 5.4 Average Packet Delay Results ..................................................................................... 50 v 5.5 Packet Loss Percentage Results .................................................................................. 57 6 Conclusion and Future Work ........................................................................................ 59 Bibliography ........................................................................................................................... 61 List of Abbreviations AFH Adaptive Frequency Hopping AMP Alternate MAC/PHY ATT Attribute Protocol AWGN Additive White Gaussian Noise BC Bluetooth Classic BER Bit Error Rate BLE Bluetooth Low Energy BPSK Binary Phase Shift Keying BR Basic Rate B-SIG Bluetooth Special Interest Group BT Bandwidth Time Product CRC Cyclic Redundancy Check CSMA Carrier Sense Multiple Access DPSK Differential Phase Shift Keying DSSS Direct Spread Spread Spectrum EDR Enhanced Data Rates EU-27 European Union FFD Full Function Device FHSS Frequency Hopping Spread Spectrum FSK Frequency Shift Keying FSR Force Sensitive Resistor GAP Generic Access Profile GATT Generic Attribute Profile GFSK Gaussian Frequency Shift Keying GMSK Gaussian Minimum Shift Keying HCI Host-Controller Interface HIT Head Impact Telemetry HS High Speed ICT Information and Communications Technology IEEE Institute of Electrical and Electronics Engineers IIHF International Ice-Hockey Federation ISM Industrial, Scientific, Medical Frequency Band ISI Inter-Symbol Interference LOS Line-Of-Sight L2CAP Logical Link Control and Adaptation Protocol LL Link Layer MAC Medium Access Control MSK Minimum Shift Keying NHL National Hockey League NLOS Non-Line-Of-Sight vi NWK Network Layer O-QPSK Offset Quadrature Phase Shift Keying OFDM Orthogonal Frequency Division Multiplexing PAN Personal Area Network PDU Protocol Data Unit PER Packet Error Rate PHY Physical Layer QoS Quality-of-Service RF Radio Frequency RFCOMM Radio Frequency COMMunications Protocol RFD Reduced Function Device RFID Radio Frequency Identification RSSI Received Signal Strength Indicator RSS Received Signal Strength SAP Service Access Point SFH Slow Frequency Hopping SM Security Manager SNR Signal to Noise Ratio SRS Side-line Response System USB Universal Serial Bus UART Universal Asynchronous Receiver/Transmitter WBAN Wireless Body Area Network WPAN Wireless Personal Area Network WSN Wireless Sensor Network List of Symbols T Coherence Time c B Coherence Bandwidth c B Doppler Spread s  RMS Delay Spread  B Coherence Bandwidth with 50% Correlation C,50% T Coherence Time with 50% Correlation C,50% f Maximum Doppler Frequency d f Carrier Frequency c v Maximum Velocity of Player c Speed of Light T Symbol Duration s P Bit Error Probability b h Modulation Index d Minimum Distance min  Signal-to-Noise Ratio (Eb/No)  Average Signal-to-Noise Ratio (Eb/No) K Rician K-factor/ Ratio of Specular Power over Scattered Power  Gaussian Filter Degradation Factor of Certain BT vii f() Fading Channel Distribution M (s) Moment Generation Function X M Number of Frequency Channels K-1 Number of Interfering Users N Number of Bits in a Packet bits p Probability of Success q Probability of Failure n Number of Trials Tx Number of Transmission a Lower Limit of Truncated Probability b Upper Limit of Truncated Probability List of Figures Figure 1 Monitoring Scenario ...................................................................................................... 3 Figure 2 Riddell SRS HIT system [17]......................................................................................... 4 Figure 3 Riddell InSite HIT system [19] ....................................................................................... 6 Figure 4 Bluetooth Protocol Stack (modified [23]) ..................................................................... 11 Figure 5 Protocol stack of Bluetooth Low Energy (modified [29])............................................... 12 Figure 6 Link Layer packet format............................................................................................. 13 Figure 7 ZigBee Network topology types................................................................................... 14 Figure 8 ZigBee stack architecture (modified [30]) .................................................................... 15 Figure 9 The sensors needed for the system. ........................................................................... 17 Figure 10 Resistance vs. Force [49].......................................................................................... 17 Figure 11 Basic FSR construction [49] ...................................................................................... 18 Figure 12 BLE channels coexisting with Wi-Fi (modified [33]) ................................................... 25 Figure 13 ZigBee channels coexisting with Wi-Fi (modified [33]) ............................................... 25 Figure 14 Simplified channel characterization functions and parameters [55]............................ 29 Figure 15 Transmitted signal in slowly faded channel ............................................................... 30 Figure 16 Constellation of BPSK and MSK ............................................................................... 31 Figure 17 Theoretical Eb/No degradation of GMSK for varying BT (modified [59]) .................... 32 Figure 18 Two-state Gilbert-Elliot Model ................................................................................... 35 Figure 19 BER of GMSK in (a) AWGN, (b) Slow & Flat Rayleigh and (c) Slow & Flat Rician with K-factor=10dB .......................................................................................................................... 39 Figure 20 BER graphs of SFH-GMSK performance with 1 interfering user and with no interfering users. ....................................................................................................................................... 40 Figure 21 PER graphs of SFH-GMSK performance in AWGN channel. .................................... 41 Figure 22 PER graphs of SFH-GMSK performance in Rayleigh channel. .................................. 42 Figure 23 PER graphs of SFH-GMSK performance in Rician channel....................................... 43 viii Figure 24 PER graphs of polling packets with 1 interfering user and with no interfering users in AWGN, flat Rayleigh and flat Rician (K-factor=10dB) channels. ................................................ 43 Figure 25 PMFs of number of transmission equal to 256 (MaxTransmit=infinite) ....................... 45 Figure 26 Expected number of required transmissions.............................................................. 47 Figure 27 Truncated probability of transmission when MaxTransmit is set to 256 ..................... 48 Figure 28 Expected number of required transmissions when MaxTransmit is set to 256. .......... 49 Figure 29 Expected number of required polling transmissions when MaxTransmit is set to 256 50 Figure 30 Average packet delay ............................................................................................... 52 Figure 31 Total packet delay..................................................................................................... 53 Figure 32 Total Delay for unlimited MaxTransmit in seconds .................................................... 54 Figure 33 Average packet delay with MaxTransmit=256 ........................................................... 55 Figure 34 Average polling packet delay with MaxTransmit=256 ................................................ 55 Figure 35 Total packet delay with MaxTransmit=256 ................................................................ 56 Figure 36 Total packet delay with MaxTransmit=256 in seconds............................................... 57 Figure 37 Packet loss percentage with MaxTransmit=256 ........................................................ 58 List of Tables Table 1 Summary details of Riddell SRS system ........................................................................ 5 Table 2 Advantages and disadvantages of Riddell SRS system.................................................. 5 Table 3 Summary details of Riddell SRS system ........................................................................ 6 Table 4 Advantages and Disadvantages of Riddell SRS system ................................................. 7 Table 5 Properties of discussed wireless technologies.............................................................. 16 Table 6 Comparison between the discussed force sensors ....................................................... 19 Table 7 Advantages and disadvantages of the discussed sensing technologies ....................... 19 Table 8 Network size for each wireless technology ................................................................... 21 Table 9 Cost of system depending on the telecommunication technology ................................. 22 Table 10 Size of RF module chips ............................................................................................ 22 Table 11 Bit rate of each wireless technology ........................................................................... 23 Table 12 Simultaneous number of connections......................................................................... 23 Table 13 link budget calculation summary table ........................................................................ 24 Table 14 Coexistence Performance comparison ....................................................................... 25 Table 15 Power consumption comparison ................................................................................ 26 Table 16 Average Packet Delay................................................................................................ 26 Table 17 Benchmarking summary table .................................................................................... 27 Table 18 Overall Performance table.......................................................................................... 27 Table 19 Mean RMS Delay Spread measurements for different industrial sites [57] .................. 29 ix 1 Introduction 1.1 Background and Motivation Nearly 40 million injuries occur annually in the European Union (EU-27), of which 15 percent are sport related [1]. This means a staggering 16.5 thousand injuries occur every day because of practicing sports in the EU-27 region. More than half of these injuries are resulted from team sports which allow one-on-one contacts like Soccer, Handball and Ice-Hockey [2]. Ice Hockey is considered as one of the most dangerous team sports because it is the highest contributor for head injuries in sports with 28 percent share in the European Union [2] and overwhelming 44 percent stake in Canada [3]. Moreover, Ice-Hockey is also a source of some severe chest injuries like myocardial infarction and commotio cordis [4] [5]. These disturbing Ice-Hockey facts raise the question: How such severe injuries can be reduced or prevented? In the last decade, there were many studies which tried to solve this problem. Studies [6], [7] and [8] have suggested the addition of new rules and the modification of existing rules to enhance the safety of the players. The main suggestions of these studies were to avoid body checking, eliminate fighting at all levels of ice-hockey participation and adding bonus points to the teams with minimal penalties. Other studies like [9] and [10] have proposed improving the sports gear used. These suggestions are logical and perhaps effective. However, these studies do not take into account the players’ safety monitoring part. This is important because for this type of sports, the warrior spirit of the players prevents them from telling the medical team of their injuries during the games. Consequently, the impacts that the player receives during the game and other hits that could not be felt immediately can develop further showing symptoms of severe injuries [10]. As a result, this entails a need for an intelligent sensing system that is able to detect the severity of collisions between players, and then sending the gathered data to a medical team to deal with the issue instantly. Moreover, it is conceivable that this system may ultimately make considerable decrease in severe injuries, and eventually increasing the career duration of a player. Also, this intelligent sensing system promises reduction in costs to the teams, as players will be treated at an early stage of the injury. 1.2 Objectives and Related Research Questions The objectives of this Master Thesis are: to review the sport safety monitoring systems literature, to identify the related system needs, to conduct a provisional analysis of the characteristics and performance of the wireless technologies options and sensing methods, to 1