Conclusion on My Web Blog

After long period of time, I ended up with my web blog because this web blog was created as part of "Regulations and standards for wireless communication" course at TU/e and we are at the end of writing period. While I have been writing on my web blog, I always tried to go from general to subjective because I believe it simplifies the understanding. I started writing with technical details which could be thought quite boring but I believe that I did not give any extra and vague information. Then I gave overview on ZigBee Alliance and ZigBee Health Care and then continued with deeper information on them. I used different terminology such as AES 128 etc but I gave small information on them to better understanding of post. Also, I tried to explain development of standard, strong sides of ZigBee Health Care compare to others which is the most crucial and enjoyable part for me. Finally, I evaluated market opportunities of ZigBee Health Care and my future expectations.

I believe I gave enough information on my web blog. I am not specialist and it was my first experience on that topic. I tried to combine knowledge thought in the class and my research through articles and internet. I hope I did not mess up :) I learned lot from this experience and I hope that someone also can enjoy and learn while reading. At this point, unfortunately I don't have any followers except prof dr. Jan Smith but I will force my friends to follow my blog :)

If you have any questions and comments about anything, please feel free to contact...

How ZigBee Health Care placed in Market now and future?

The future of Wireless Sensor Network is bright because it consists group nodes or devices.Each device has ability to communicate with other devices and they convey their observations through other devices to a destination. Most importantly with developing technology, wireless sensor networks smaller and more cost effective because of miniaturization process.

By means of developments and miniaturization, wireless sensor network technology has grown rapidly in those 10 years. Sales numbers are proof of this development. In USA, between 5 and 7 billion dollar has been obtained from this sector. In the future, I believe that people will need ZigBee Health Care much more compare to today. In the meanwhile, my belief is supported by Forrester Research. According to their research, they expect US chronic disease device market will grow from 3.8 billion dollar to 26 billion dollar in 5 years.

Apart from USA, in European Union and Japan, market has been growing because of elderly population and it is expected that total potential market will be 87.8 million people.

It is good to take a look US based Chronic Disease Self-Management Program for understanding the importance of ZigBee Health Care. It is a program which uses for different chronic illnesses for example arthritis, diabetes, heart diseases etc. At the end of the program, there is an evaluation and this evaluations show that the patients who took part in this program, improved their health status and behaviours. Although it helps to people to recover, there is a debate about cost because it is around 200 dollar per patient which is quite high for many people. After this program is automated through wireless sensors, patients pay quite less comparatively which results in spread this program all over the world.

AES 128

In the previous post, it is mentioned that ZigBee uses AES 128 encryption. I thought it is good to give brief information about it because security is one of most important issues for everyone.

AES refers to Advanced Encryption Standard which is a symmetric key encryption standard. This standard has three block ciphers which are AES 128, AES 192 and AES 259. All of them have 128-bit block size with key sizes of 128, 192 and 256 bits. ZigBee uses AES 128. When we look at the history of AES, it was announced by National Institute of Standards and Technology in 2001. After announcement, 5 years standardization process took place. At the end of this process, Rijndael was selected as most suitable one. in 2002, it has started to be effective because it was approved by the Secretary of Commerce.

I don't want to go into deep explanation of AES because it requires many other knowledge. I believe that explanations are enough to prove security of AES.

Why is it preferable and successful?

ZigBee Health Care is reliable because it does not have any side bad effect on human body. The reason is that as mentioned in one of previous posts, ZigBee operates at lower level of average cell-phone in significant amount although it has almost same power level with Bluetooth devices. On the other hand, it has at least 1000 times less duty cycles than Bluetooth devices. Other important aspect is that other devices operateing ISM bands for medical devices using ZigBee but it does not create any problems because ZigBee has very strong tolerance against any interferences which shows its robustness. ZigBee is tested at The Las Vegas Convention Center because it is one of the worst places for wireless devices but ZigBee performed very well. It is the proof that ZigBee can work without error in any environment.

The important advantage of ZigBee is that it uses Mesh-Networking which helps communication with other radios in the network. Mesh-Networking allows to communication with multiple possible paths to its destination which proves its flexibility. In addition, by means of mesh-networks, networks are enabled to grow in size and physical distances are covered. Point to point and point to multipoint topologies refers that data packet is vulnerable to blockage or interference because of single path. Also, it is easy to add devices to ZigBee network. Most importantly, fast and easy association between devices are allowed by ZigBee's pairing process. High degree flexibility ans stability are obtained by using different algorithms which include hierarchical tree, neighbor and table-based routing.

Other important aspect of security for confidential medical data. It was mentioned one of the previous posts that ZigBee uses AES 128 encryption which is known as strongest level of security. Also, many governments and militaries use this security system. In addition, ZigBee Health Care public application profile has specific security features for medical environment privacy. In addition, ZigBee has a strict certification procedure, it is because if someone buys certified ZigBee Health Care device from different vendors, communication and interoperability are guaranteed.

ZigBee Health Care Benefits

It should be understood from all my posts that I prefer giving general information and then focusing on ZigBee Health Care. The reason is that I believe it could be followed easily.

In the following, I will give explanation about ZigBee Health Care benefits which is the fundamental of understanding next posts.

It can be divided into 4 parts:

1) Easy

• Internet connection for greater access and control
• Automatic features
• Reduction of the cost
• Interoperability

2) Secure

• Personal data is secured by AES 128
• Regional regulatory compliance

3) Affordable

• Open standards helps to reduce cost in the market
• Healthcare cost reduction
• Home tv to display data from medical and non-medical devices

4) Interoperable

• Interoperability between medical and non-medical devices
• Control and monitoring device integration

Why is it called Alliance?

In previous post, it is mentioned that ZigBee is an alliance. In this post, I will try to explain why it is called Alliance.

It is known that ZigBee uses IEEE standards as a base. Also, it has been established by many companies and support of some organizations. ZigBee alliance membership does not have any specific rules which means anyone can join. The other important aspect of ZigBee is interoperability which improves cooperation between companies. In addition, confidentiality is an important factor. Only members can access to the ZigBee standard. When standard becomes well known, membership of IEEE gives reliance. In addition, small companies actively involved because Zigbee aims cheap final products and they don't want to involve in long time consuming process.

ZigBee Alliance Membership

Three different kinds of ZigBee Alliance membership are possible. These are: participants, adopters and promoters. I will give brief information about them in the following.

Firstly, I will start with participants. These members can be called as regular members. They can actively participate to the development process and have rights to access to specification and voting. Secondly, adopters have rights to access to specifications like participants but they don't have right to vote. Thirdly, promoters are crucial members of ZigBee because they play key role in giving final decisions and approvals. Now, there are 12 promoters in Alliance.

In the following, organizational chart which is taken from www.zigbee.org is shown.

History of ZigBee Alliance

After it was thought that Wi-Fi and Bluetooth were not good enough and suitable for some applications, it was decided to have ZigBee style networks in 1998, actually it was realized that need for self-organizing ad-hoc digital radio networks. There was a problem with Philips because Philips semiconductors stopped the investment. On the other hand, Philips lighting kept being a promoter member of ZigBee Alliance board of directors. Officially, ZigBee Alliance was announced in October 2004. It had more than 100 member companies almost all over the world. Also, number of members were increased almost double of previous years. In addition, next year (after December 2005), more than 200 companies became member which is quite high number.
Most importantly, ZigBee specification were approved on 14 December 2004 which is named as ZigBee 2004 Specification. After approvement, its public availability was announced 13 June 2005. In September 2006, ZigBee 2006 Specification was announced with member availability version. After all these developments, throught the end of 2007, ZigBee PRO which is final version was announced. It contains enhanced ZigBee specification.

Wireless Sensors Application Areas

After explaining technical details and overviews, I decided to give information about applications of wireless sensors for better health care. The parts which were explained before could be thought as boring but I believe this part can take more attention of readers...

Application areas are divided into 3... First part contains chronic disease (episodic patient, continuous patient and patient alarm monitoring scenarios). Second part contains personal wellness (senior activity and safety monitoring scenarios). Finally, third part contains personal fitness (monitoring and tracking fitness level and personalized fitness schedule scenarios).

 I will give brief information about all of them in the following.

1) Chronic Disease: It is known that chronic diseases refer to many health problems such as sleep disorders, asthma, heart diseases etc. It is because they require some kind of health monitoring. In that sense, episodic patient monitoring is used for tracking specific indicators and identifying the progress of the disease and recovery. Continuous patient monitoring is used for patients who are in hard conditions such as needed frequent measurement of health status. In addition, patient alarm monitoring is used for specific reason to trigger the alarm.

2) Personal Wellness Monitoring: Usage area is mostly people at the age of 65 and older.It concerns person's activity and safety. Sensor activity monitoring scenario is used for monitoring elderly people's daily activity. It contains monitoring non-medical sensors such as motion, temperature, home etc. Safety monitoring scenario is used for home environment safety. Also, could be used for monitoring safety hazards.

3) Personal Fitness Monitoring: It can be used for in the home and health fitness centers. Monitoring and tracking fitness level scenario is used for tracking the fitness level or progress of an individual. Personalized fitness schedule scenario is used for tracking of a person in fitness center by instructor.

ZigBee Health Care Features

Before explaining thoroughly, it is important to have idea about general ZigBee Health Care features. They are listed in 6 subtitles such as aging independently, chronic disease management, health and wellness, customizable security, supported devices and ZigBee technology.

1) Aging Independently
    - Reliable patient monitoring
    - Freedom of mobility
    - Safe and active monitoring sensors
    - Real time location capabilities
2) Chronic Disease Management
     - Prompt feedback for better self management
     - In order to manage multiple chronic diseases gives collaboration between devices
3) Health and Wellness
     - Body worn sensors for sports
     - Precision time stamps for synchronization and high accuracy monitoring
4) Customizable Security
     - Conforms with regional regulatory environments
     - Efficient key generation, distribution and management
     - Scalable support for privacy and security
5) Supported Devices
     - IEEE 11073
     - Medical and non-medical devices
     - Data management
6) ZigBee Technology
     - Long battery life
     - Supports multiple network topologies
     - Networking flexibility and wireless range variety
 

ZigBee Health Care

Firstly, the aim of designing ZigBee Healt Care is usage by assistive devices operating in non – invasive health care. In order to reach this aim ZigBee Alliance has been focused on healthcare space. Also, it allows sharing data between medical and non-medical devices as industry wide standard.

Public application profiles could be thought as message formats and agreements of messages, also processing actions which result in creating interoperable and distributed application entities residing on separate devices. Over ZigBee network, commands can be sent, data and process commands could be requested.

ZDO represents the ZigBee Device Object which is a predefined base class of functionality. The best thing is that it gives an interface between ZigBee health care profile and APS (application support sub-layer). All operations in a ZigBee protocol stack has been satisfied. In addition, it is also helps initializing the APS, NWK (network layer) and security service provider.

In the Figure posted below, Application (APL) layer is shown. The areas in blue are based on the ZigBee specification and shows ZigBee health care definitions, Device specializations are defined by IEEE which includes IEEE 11073 specialization for point of care medical device communication. R-11073 also known as the 11073-20601 standard is one of the standards of IEEE 11073 and it is a transport independent, optimized exchange protocol. Three methods are provided by this method:

1.       Logical connections between devices are established.

2.       The capabilities of devices are presented.

3.       Communication needs are serviced.

And ISO/IEEE 11073 are completely supported by ZigBee Health Care which also supports all device specializations for instance blood pressure monitor, pulse monitor and oximeter or glucose meter etc.

 This Figure is taken from ZigBee Alliance website. For people who are interested, the website is http://www.zigbee.org/

Protocol Architecture

The physical layer

The physical layer gives data transmission service and interface to the physical layer management entity. It also gives access to all layer management function and database of information to the related personal area networks. By means of Physical layer, channel selection and signal management functions can be performed. Also, physical RF transceiver could be managed.

The physical layer uses one of the 3 unlicensed frequency bands written below:

1)      868.0 – 868.8 MHz: Europe (one communication channel 2003 – 2006)

2)      902 – 928 MHz: North America (2003 – 10 channels, 2006 – 30 channels)

3)      2400 – 2483.5: worldwide usage, allows up to 16 channels 2003 – 2006.

The original of the standard is 2003 version which specifies two physical layers based on direct sequence and spread spectrum techniques. Whereas direct sequence works in the 868 / 915 MHz bands with transfer rates 20 and 40 kbit/s, spread spectrum techniques work in 2450 MHz band with transfer rate of 250 kbit/s.

After 2003, it is revised in 2006, 2007 and 2009. Specification are explained in the following:

Firstly, 2006 revision improved both maximum data and transfer rates. 868 – 915 MHz mostly uses phase shift keying or sometimes offset quadrature phase shift keying. It is also defined by means of binary and amplitude shift keying combination. Also, it supports dynamic switching between layers.

Secondly, it is improved in 2007. Improvements are made by means of Direct Dequence Ultra-wideband (frequency ranges are between 3 GHz and 5 GHz and between 6 GHz and 10 Ghz) and Chirp Spread Spectrum usage (2450 MHz ISM band spectrum)

Finally, in 2009 extra physical layers have been released such as 780 MHz band using O-QPSK or MPSK and 950 MHz band using GFSK or BPSK. Also. It varies in China and Japan. In China, 314 – 316 MHz, 430 – 434 MHz and 779 – 787 MHz bands are newly opened. In Japan, 950 – 956 MHz is newly opened.

 

The MAC layer

The Medium Access Control layer enables the transmission of MAC frames through the use of physical channel. The good point is that it offers data service, management interface and access to physical channel. In addition, frame validation is controlled by MAC. Finally, time slots and node associations are guaranteed.

Higher Layers

There are different type of higher layers. Firstly, ZigBee was built on this standard and it offers integral solutions. In addition, it is used by TinyOS, Unison RTOS and DSPnano RTOS.

IEEE 802.15.4

In the previous post, it is mentioned about IEEE 802.15.4 which is the basis for ZigBee. It is because it is important to explain IEEE 802.15.4 in order to understand next posts better.

IEEE 802.15.4 is for low rate wireless personal area networks (LR-WPANs) and it specifies the media access control and physical layer.

Before going through Protocol Architecture, I will give quick overview on IEEE 802.15.4. It focuses on low cost and low speed ubiquitous communication between devices. Also, offers low cost communication related to low power consumption. Communication range is around 10 meter with transfer rate of 250 kbit/s. Also, depending on resulting effect of power consumption, lower rates could be considered. It is possible to get very low manufacturing and operation costs and technological simplicity as main feature of 802.15.4 among WPAN’s. In addition, it is included to devices power management functions for example energy detection and link quality.

Quick Overview on Zigbee Standard

It is good to start with overview on ZigBee technology. First reason to choose Zigbee technology is that it has ability to connect a large number of devices into a single network. Second one is that it has efficient low – power connectivity. For ZigBee technology, globally available license-free 2.4 GHz frequency band is used because wireless applications could be enabled by means of a standardized set of high level communication protocols sitting atop cost-effective, low-power digital radios based on the IEEE 802.15.4 which is standard for wireless personal area networks. The good thing is that ZigBee uniquely offers low-latency communication between devices without the need for network synchronization delays.