With the gradual progress of urbanization in China, the number of urban high-rise buildings continues to grow, and the elevator has become an irreplaceable means of transport for urban vertical transportation. According to incomplete statistics, as of the end of 2013, the total installed domestic elevator has more than 2.8 million units, and is also continuing to grow. In recent years, frequent elevator accidents have aroused the concern of all walks of life on elevator operation safety. The reason is that, in the past, the operation and maintenance management system of elevators relying on manpower can no longer meet the current situation of the increasing number of aging elevators.

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WiMAX technology set up a wireless elevator fault monitoring and alarm system
Written By Calio Huang
With the gradual progress of urbanization in China, the number of urban high-rise buildings
continues to grow, and the elevator has become an irreplaceable means of transport for urban
vertical transportation. According to incomplete statistics, as of the end of 2013, the total
installed domestic elevator has more than 2.8 million units, and is also continuing to grow. In
recent years, frequent elevator accidents have aroused the concern of all walks of life on elevator
operation safety. The reason is that, in the past, the operation and maintenance management
system of elevators relying on manpower can no longer meet the current situation of the
increasing number of aging elevators. Therefore, an advanced and effective scientific
management mode is urgently needed to ensure the safe operation of elevators. With the rapid
development of Internet of Things technology and strong national support, Internet of Things
technology has been more and more applications. As a typical application of Internet of Things,
elevator monitoring system provides a more effective management mode for people. The
IOT-based elevator monitoring and management system can effectively predict and predict
elevator accidents; carry out quick repair on the elevator faults, thus ensuring the safe and
effective operation of the elevator, reducing the frequency of elevator accidents and reducing the
elevator accident losses.
At present, industry experts have conducted a series of studies on the elevator monitoring
system. It has become a consensus that the wireless monitoring and control systems of the past
were retrofitted into the Internet of Things and built into the Internet of Things. The traditional
monitoring system for elevators is based on technologies such as 3G and WLAN The programs of
wireless network transformation have a certain range of applications. These systems have not
only played a significant role but also exposed some shortcomings. For example, the bandwidth
of 3G communication is relatively narrow, the capability of audio and video signal acquisition and
real-time transmission is not high, And data transmission will continue to generate tariffs, the use

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of higher costs. WLAN technology communication bandwidth to meet the requirements, but the
wireless signal transmission distance is shorter, the relative reliability is not high. With the
determination of IEEE802.16e and IEEE802.16m mobile WiMAX standards, WiMAX technology
can provide IP-based audio and video signal transmission due to its high access rate, make up for
the lack of 3G and WLAN technologies, and rely on WIMAX technology to build a wireless
elevator Monitoring system can better adapt to the system requirements for the transformation
of things.
1 .elevator monitoring alarm system introduction
Elevator monitoring alarm system is based on the elevator detection technology developed from
the elevator fault diagnosis warning system, early detection system belongs to the elevator
elevator elevator control system part of the operation, mainly rely on the sensor on the elevator
car quality, door signal, flat Layer signal, safety gear and other state parameters acquisition, the
data back to the control terminal, used to control the stable operation of the elevator. Nowadays,
due to the need of elevator fault diagnosis, the system has been gradually improved and more
and more advanced sensors have been added, which makes the system more comprehensive and
comprehensive in perception of elevator operation status. Elevator monitoring and alarm system
make full use of this achievement, combined with modern communication technology, the
operation of a number of elevators within a certain area will be transmitted to a monitoring
computer, the computer to analyze the elevator failure to judge, timely feedback to the elevator
maintenance staff, To ensure that the elevator abnormal situation can be timely response and
treatment.
1.1 WiMAX communication technology introduction
WiMAX is a wireless broadband standard introduced by the IEEE (Institute of Electrical and
Electronics Engineers) and has released several versions of 802.16 to 802.16m since 2001. The
system uses IEEE802.16e standard, can support fixed and mobile broadband wireless access, the
working frequency band of 2 GHz ~ 6 GHz, duplex mode FDD (frequency division duplex) and TDD
(time division duplex); non-visual coverage Radius of km level, transmission peak up to 75 Mb / s,
support for all IP network layer protocol and QoS technology, fully meet the wireless escalator
monitoring communication network in the district to build the various needs.
1.2 monitoring alarm system topology
The system will be embedded micro-computer technology, WiMAX wireless communication
technology, elevator fault detection technology, Internet of Things technology, the elevator fault
monitoring and alarm terminal and residential property, security companies, local special
inspection and monitoring center computer link, Multi-level elevator monitoring alarm and fault
diagnosis network, to achieve the centralized monitoring and management of the elevator. The
elevator owner can monitor the running status of the elevator in real time through this system;
the maintenance company can refer to the elevator operating parameters to remotely judge the
type of the fault, formulate the treatment plan and organize the maintenance work through the
system; the relevant supervisory department such as Special Procuratorate provides the Elevator
running status and maintenance records statistics, effective supervision of the elevator operation
support. The system can improve the modern operation of the elevator management and
maintenance quality of the elevator.

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Elevator fault monitoring and alarm system consists of elevators, monitoring terminals, WiMAX
base stations, local servers, special inspection center server, monitoring PC and smart handheld
terminal. Monitoring alarm terminal is an important component of the bottom of the system, the
monitoring terminal is connected to a set of sensors responsible for collecting elevator operating
parameters, with a typical fault reference point, when the elevator operation is abnormal, either
manually or by the passenger manually trigger the alarm, apply for the establishment of voice
and video transmission Channel, fault status parameters at the same time upload, elevator
normal operation can accept local and remote access. The WiMAX base station is connected to
the local server of the cell and is responsible for establishing a wireless regional broadband
network in the cell, allocating a network identifier for each monitoring terminal, and accepting
terminal network access requests. After establishing the network, the terminal is responsible for
receiving data uploaded by each terminal and transferring the data to a local server. The local
server is responsible for statistics of each elevator's parameters in the district to the local
database, providing local and remote access queries, and synchronizing data with the special
inspection center server regularly through the Internet. Residential property monitoring PC is
responsible for monitoring the operation of the local area network elevator, elevator failure in
response to the elevator monitoring terminal connection request, the establishment of voice and
video communications, elevator fault information stored in the local database, access to special
inspection center server, upload fault elevator operation Parameters for troubleshooting services,
immediately after receiving the diagnostic results sent by SMS to the maintenance staff. Special
inspection center server is responsible for the storage, statistics, management of all elevator fault
information in the region, due to strong processing performance, which can be installed in the
elevator fault diagnosis software for all elevators in the region to provide fault diagnosis services,
but also set up a dedicated website, Provide relevant personnel check elevator, operation and
maintenance work, test work information.
1.3 monitoring alarm terminal hardware components
The elevator monitoring and alarming terminal is the core part of the system front-end hardware
and consists of embedded ARM computer, data acquisition module, wireless communication
module, control module, multimedia module and power supply module.
1.3.1 Master computer
The main control computer adopts the industrial control single-board microcomputer with the
A20 chip as the core, the CPU adopts the ARM Cortex-A7 architecture, the dual-core 32-bit
low-power microprocessor with 1 GHz frequency, and the on-board peripheral hardware
resources include 1 GB operation Memory, 4 GB NAND Flash memory, 5 full-duplex serial ports, 2
IIC interfaces, 1 SPI interface, 2 10-bit ADC conversion interface and multiple general-purpose
input and output interfaces for external sensors and wireless communication modules.
1.3.2 acquisition module
The acquisition module consists of a plurality of sensors distributed in various parts of the
elevator. The sensor is independent of the elevator control system and is mainly used for
collecting the operation parameters of the key parts of the elevator. The sensors include
acceleration sensor, load cell, vibration signal sensor, leveling signal sensor and door sensor signal
sensor. These sensors are connected to the monitoring alarm terminal through the signal cable,

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and real-time acquisition of elevator operating status parameters.
1.3.3 multimedia module
Multimedia module consists of 14-inch LCD screen, audio amplifier, speakers, electret
microphone and camera components. When the elevator is in normal operation, the multimedia
module can play a promotional video of riding the elevator related knowledge, and also can play
the multimedia advertisement, and the advertisement can obtain the income to offset the
system operation and maintenance costs. When the elevator fails, the multimedia module can be
used as an alarm rescue video phone, Elevator audio and video signals inside, to help trapped
people.
1.3.4 power supply module
The power supply module consists of a main power supply and a backup power supply. The main
power supply is an AC150-220 V wide-voltage input DC12V5A output switching power supply.
The backup power supply is an uninterruptible power supply module composed of a 12V7Ah
lead-acid battery and a charge-discharge management circuit, Run for 1 h.
1.3.5 WiMAX communication module
The system uses WiMAX wireless broadband networking technology, communication module
selection Intel Centrino Advanced-N + WiMAX 6250 wireless network card, this card follows the
IEEE802.16e Wave2 protocol, working in the 3.5 GHz band, the uplink transmission bandwidth of
6 Mb / s, downlink Transmission bandwidth of 20 Mb / s, the use of Mini PCI-E half-height card
design, communication interface for USB2.0, provided by Intel's official Linux system and
Windows system drivers.
1.3.6 RF card reader module
Elevator operation and maintenance and management personnel with identification card, used to
record the daily maintenance of the elevator log, including maintenance start time, end time and
maintenance, management personnel identity information. The device uses RFID radio frequency
identification technology, the reader module selection Ming Tai MRF-35-MEM non-contact IC
card reader, read and write card type in line with MIFARE standards, read and write frequency of
13.56 MHz, the communication interface is RS232, communication The frequency is 115 200 b /
s.
1.4 WiMAX wireless network set up
The IEEE802.16 standard specifies two standard networking modes, PMP (Point-to-Multipoint)
and Mesh (Mesh Network). Since the coverage radius of the base station in this department is
not required and the number of network access terminals is small, and the terminal type is fixed ,
Choose a more appropriate PMP networking. The complete WiMAX network architecture
consists of core network, base station, user base station, relay station, user terminal equipment
and network management. The signal coverage radius required by this system is about 1 km,
much lower than the standard 50 km, Therefore, the network structure can be simplified.
Only an integrated WiMAX base station is arranged in the central high point of the residential
area. The elevator monitoring terminal is directly connected to the base station for networking.
Only a small number of signal blind areas are set up for signal relaying of small-scale WiMAX
wireless APs to realize all elevators in the area Monitoring terminal network coverage. The
WiMAX base station transmits the data uploaded by the terminal to the cell monitoring server via

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the network cable. The specialized processing software is responsible for data extraction, analysis,
collation and storage. The cell server connects to the Prostitute server through the operator's
network, performs regular data synchronization, applies fault diagnosis and diagnosis services,
and other necessary work.
2 system software
The system software includes the terminal software and the monitoring computer software. The
program design adopts OS (operating system) + APP (application) mode, the terminal OS adopts
the Linux operating system with the graphical interface removed, and the APP software is based
on the cross-platform C ++ application Framework QT development. Monitoring computer
operating system using Windows 8, APP based on the Visual Programming Environment under
Windows Delphi development.
2.1 terminal application
Terminal applications in accordance with the actual function can be divided into four main
modules of data acquisition and processing, communication, event judgment processing and
multimedia playback.
Data acquisition module mainly for the elevator operating state parameters collected. To ensure
the reliability and real-time data transmission, the text data is designed to be transmitted using
the TCP protocol, and the audio and video data are designed to be transmitted using the RTCP
protocol over UDP. The event judgment processing mainly analyzes the sensor data, compares it
with the built-in normal parameters, judges the type of the fault according to the abnormal type
of the data, triggers the alarm and uploads the fault parameters, and also performs remote
access and command parsing execution. Multimedia player module is responsible for audio and
video decoding playback.
2.2 monitor computer applications
Monitoring computer applications according to the function can be divided into communication,
data processing, transaction processing and human-computer interface 4 modules.
The communication module consists of 4 parts: (1) receiving the data packets uploaded by the
terminal through the TCP protocol, sending instructions to monitor the remote interaction
between the computer and the terminal; (2) receiving the terminal video telephony data stream
via the RTCP protocol and releasing the advertisement file update; (3) In case of emergencies For
consultation by experts, multi-party voice communication can be set up through IP phone; (4)
The necessary elevator status is sent to the rescue or maintenance personnel mobile phone by
text message. The data processing module unpacks and extracts the data packets uploaded by
the terminal, classifies a plurality of data corresponding to different terminals, and adds the time
information to a local database. The transaction processing module compares the terminal data
with the pre-stored normal reference data to determine the police intelligence. If there is any
abnormality, the alarm mechanism is triggered. The relevant personnel are notified by telephone
short message, the fault parameters are uploaded to the special inspection center server for fault
diagnosis service, and the local Database and special inspection center database synchronization.
Human-computer interaction interface simulates the status of elevator, car screen, providing
database search window for relevant personnel inquiries.

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3 .Conclusion
Compared with WIFI technology, WiMAX can provide wireless broadband connection in a wider
geographical area than in WIFI technology and WiMAX wireless network needs to be set up in a
range of up to km in non-visual distance. Compared to the advantages of using this technology to
build the wireless elevator fault monitoring and alarm system installation and layout, flexibility
and high maintainability. The system provides a solution for the transformation of the Internet of
Things into the aging elevator in the later stage of its service life at this stage.