Telemedicine system provides transmission of medical data of patient, e.g. vital signs and other reference data. Depending on the need and availability of communications infrastructure, several telemedicine applications have been successfully implemented over wired communication technologies, such as:

The major motivation and benefit from wireless LAN is increased mobility. WLAN provides a flexible data communications system, implemented as an extension to or as an alternative for a wired LAN. Various advanced medical applications such as remote follow-up, remote diagnosis, intervention on non-transportable patients, remote monitoring, remote assistance, and medical e-learning are expected to be improved by using WiMAX.

 

Mobile telemedicine is a promising area in which it enables real-time interaction of medical data, voice and video in a wireless and mobile environment. Some wireless standards are Wireless sensor network based on wireless technology has been introduced into telemedicine system to collect data about the status and medical history of the patient. For some chronic illness, frequent measurements of vital signs are necessary to impression about the current status and also important for the optimization of the treatment. Thus, the focus is on patients who need continuous monitoring of their health status.

 

Patient monitoring devices can be divided into two categories:

 

Alert monitoring: Patient's data is examined against the preset ranges or boundary limits. Then the system determines whether a patient is in need of help.

 

Data acquisition (and monitoring): System is designed to monitor a patient with collecting and retaining all the data for further study and analysis. A data acquisition system has some characteristics as follows:

With the obvious benefits seen from the improvements and implementations in wireless networks, the opportunity to adopt it to healthcare systems is inevitable. The wireless medium would provide more flexible access both to doctors and patients, by the use of mobile stations. The wireless interface would also eliminate the problem of installing Ethernet ports in each patient room (which would be required in a wired LAN), thus, providing convenience to patients, doctors and reducing costs.

 

 

This section presents some envisioned futuristic scenarios that take advantage of integrated WiMAX and IEEE
802.11/WLAN networks for telemedicine  service0073. Figure below shows a high-level system model based on the integrated WiMAX and WLAN wireless network for a telemedicine network connecting hospitals, clinics, drug stores, mobile ambulances, a patient information management database, mobile specialists, and patients at home as well as mobile patients. Single-mode (SM) MNs equipped with one interface, dual-mode (DM) MNs, dual-mode WLAN APs, and WiMAX BSs are potential components of this heterogeneous wireless network. The scenarios described in Fig.elicit the benefits and illustrate some issues in integrated WLAN and WiMAX networks. The hybrid system can be divided into five sub-networks: body area networks (BANs), home care network/tele-home care, intranet of a healthcare provider, including a hospital, a clinic, and a drug store, a network between the patient home and the healthcare provider, and a mobile telemedicine network for mobile patients and health service providers. A wireless heterogeneous network of WLAN, WiMAX, and 3G cellular networks (dashed lines) is also shown in Fig.

The integrated WiMAX and WLAN wireless telemedicine networks can be deployed in the following scenarios:

BANs: The BAN is a particularly appealing solution to provide information about the health status of a patient in medical environments such as hospitals or medical centers. The integrated 802.16/802.11 wireless-network-based tele-medicine system can also provide medical services for BANs through SM (BAN2 and BAN3) or DM (BAN1) mobile clients. The mobility of BAN2 is limited within WLAN2 due to only one WLAN interface being equipped with the client.

Figure below shows the health monitoring scenario for elderly people in a retirement community or nursing home.

The Electrocardiogram (ECG), Blood Pressure (BP), and 3-axis ACCeleration (ACC) signals located on the body of elderly people are monitored and recorded to the main control center (healthcare service provider).

 

There are two layers of network architecture in this system:

 

The first layer is defined by BAN, which constitutes the communication between sensors on the body with the controller on the wrist. The ECG, BP and ACC sensors measure and store medical signal in memory and data is sent to the controller periodically through the ZigBee technology. This is an uplink and unidirectional transfer. The ZigBee device in the sensor node operates as Slave (S) and ZigBee PAN Coordinator in the controller acts as Master (M). The controller receives data from all sensor nodes during the Contention-Free Period (CFP).

 

The second layer transmits the health care information received from ZigBee to the infrastructure network through WLAN. The controller acts as a 'gateway' that links BAN to the WLAN infrastructure. The buffered data in the controller is transmitted to the WLAN Access Point (AP) through IEEE 802.11b WLAN technology. This is also an uplink and unidirectional transfer. Fig below depicts the traffic pattern in a typical wearable health monitoring system.

For emergency cases, data transmission operates as follows.

 

When sensors detect a life-threatening sign, for example the ECG signal reaches a critical threshold, the controller shall recognize the danger, and transmits a warning message piggybacked onto the ECG data to the control center. An emergency team can be immediately dispatched to assist the elderly person in distress. Other WLAN traffics due to email or internet activities also exist in a health monitoring environment.

Home care network/Tele-Home Care: Home care is a growing field in healthcare and is a promising solution to the medical problems of modern society. The population census indicates an increasing trend of the senior population. Furthermore, modern life is becoming more stressful than ever; therefore, prolonged treatment is becoming more necessary. Home care via treatments in the patient's house with the assistance of the family reduces the need to transport patients between homes and hospitals.

 

In the integrated WiMAX and WLAN networks, patients may reside at home for remote patient monitoring through either connecting directly to a WiMAX BS equipped with a WiMAX client like Home2, or connecting to WLAN dual-mode APs like Home 1.

 

Intranet of a healthcare provider/intra-hospital services: WiMAX is a more practical and cost-effective solution for hospital intranet deployment due to the relatively larger coverage area of WiMAX networks than that of WLAN APs. The deployment of a WiMAX network in a hospital will reduce operation and maintenance costs, while offering full mobility support for patients and medical staff.

 

Clinics and drugstores: In contrast to a hospital, WLAN APs can likely provide enough coverage for clinics and drugstores. Therefore, dual mode WLAN APs can be deployed at clinics and drugstores to communicate with healthcare centers through WiMAX interfaces and to provide local wireless coverage through WLAN inter-faces.

Wireless video telephony: A number of telemedicine applications are based on the transmission of medical video, such as remote medical action systems, patient remote tele-monitoring facilities and transmission of medical videos for educational purposes. High quality videos/images are required to ensure proper diagnosis and/or assessment. Video transmissions over a WiMAX network have proved to be an effective and efficient platform in providing proper video content delivery.

 

VoIP services: WiMAX can also be used for VoIP services. Telephone bills can be drastically reduced as a result of the use of VoIP for communications among hospitals.

 

QoS support is vital in integrated WiMAX and WLAN for e-healthcare service because various types of time-sensitive data should be communicated in such a service. For example, real-time communications and large enough bandwidth is required for transmitting high-resolution digital videos and images in mobile robotic systems. Providing QoS in the integrated IEEE 802.16/WiMAX and IEEE 802.11/WLAN network is a challenging issue. The need for efficient
interworking between IEEE 802.16/WiMAX and IEEE 802.11/WLAN arises in order to support QoS for delay-sensitive and bandwidth-intensive applications.

 

IEEE 802.11e employs a channel access function, hybrid coordination function (HCF), to support QoS provisioning in IEEE
802.11/WLAN networks. HCF uses both a contention-based channel access method, enhanced distributed channel access (EDCA), for contention-based transfer, and a controlled channel access, referred to as HCF controlled channel access (HCCA), for contention- free transfer. EDCA and HCCA provide QoS support over existing distributed coordination function and point coordination function schemes, respectively. EDCA defines four access categories (ACs): AC_VO with highest priority, AC_VI, AC_BE, and AC_BK with lowest priority corresponding to voice, video, best effort, and background traffic, respectively. The priorities are achieved by differentiating the contention window (CW) size and arbitration inter frame space (AIFS) time. Therefore, higher-priority ACs have smaller CWs and shorter AIFSs. The EDCA mechanism can only provide relative differentiation among service categories, but not absolute guarantees on throughput and delay performance, and it may thus starve lower-priority flows. HCCA provides QoS service by using signaling, scheduling and admission control. It defines a super frame containing a contention-free period followed by a contention period. During the contention-free period, only nodes which are polled by the AP are eligible to transmit for a burst period assigned by the AP. IEEE 802.11e defines eight traffic categories (TCs): TC6 and TC7 for voice, TC4 and TC5 for video, TC0 and TC3 for best effort, as well as TC1 and TC2 for background information. When a new TC starts, the node needs to send a service request to the AP providing its traffic specifications so that the AP will perform admission control to decide whether to allow the new flow for service.

 

In the delivery of medical data, some type of data such as real-time medical video streaming requires strict QoS support. In order to support such requirements, the extension of the standard 802.11e EDCF scheme, referred to as medical channel-adaptive fair allocation, has been proposed [13].

 

Different from IEEE 802.11/WLAN, IEEE 802.16/WiMAX was designed from the beginning with QoS in mind and defines five different types of services for different types of traffic flows as follows:

Telemedicine has evolved quite a bit in the last 25 years. Its original application involved point-to-point, live sessions between patient and provider. Point-to-point sessions allow a healthcare provider and patient to interact from remote locations. Often it is done through video conferencing so that the provider can see the patient. It is also sometimes done through audio connection. This system has worked very well.

 

Telemedicine has the potential to increase access to specialty care for millions of Americans, including the homebound and those in remote communities. Many believe telemedicine will one day play a key role in improving care and lowering costs. Studies show that compared to usual care, people who underwent checkups via videoconferencing have reported that telemedicine was convenient and made communication with a specialist simpler. The study showed that home-based monitoring systems that automatically sent information --about issues such as heart rhythm abnormalities -

- to on-call nurses and doctors reduced hospitalization rates by 63 percent.

 

There are some market trends that will shape telemedicine and telehealth in the immediate future. These trends represent major changes from the existing norm, creating new challenges and opportunities for the industry

 

 

Reimbursement has been the Holy Grail for telemedicine in America but the rapid growth of managed care, Accountable Care Organizations and medical homes are changing the way we pay for telemedicine services. One quarter of all Americans--73 million patients--are now covered under a managed care health insurance program. With this shift, the focus of decision-making is gradually turning to local and regional healthcare decision makers.

 

 

Medical images, like x-rays and CT scans, have been viewed in digital form for forty years. Teleradiology is now so common that many hospitals don't recognize the name - outsourcing part or all of a radiology program is just the way things are now done in healthcare. Providing 24/7 services by a radiologist, using telehealth technologies, may be the first form of telemedicine that becomes a true standard of care; as such it would be included in state, federal and Joint Commission requirements and be a basis for court decisions on medical liability and hospital accountability. 

 

 

Outsourcing the interpretation of medical images is now used by most hospitals in the United States. A relatively new and related market is the use of private firms of medical specialists to provide other remote clinical consultations. If a hospital can completely outsource its (non-interventional) radiological services, why not outsource neurology, psychiatry or a host of other clinical services? A series of small vendors have emerged to provide telehealth consults for stroke care, mental health, hospitalist services, and dermatology. Some of these firms may be considered competitors to hospital- based telemedicine programs. Look for mergers and expansions of such enterprises as the market grows.

 

 

Mobile Health (mHealth) is a hot topic and an important addition to the mix of technologies changing the way healthcare is delivered. However, as many people have acknowledged, the mHealth sphere is full of yet-unproven promises and uncertainty about how to pay for these technologies.

 

 

Federal grants have helped to establish about 200 telemedicine programs linking multiple health centers throughout the country. Almost all these programs are hub-and-spoke models, where a large central hospital unidirectionally provides services to connected sites. An alternative approach, connecting multiple centers using a true network design, is starting to gain favor. This new model is based on paid memberships, with services delivered from any point on the network to any other point. Both the Arizona Telemedicine Program and the Ontario Telehealth Network epitomize this new approach.

 

 

Once confined to international charities and a few remote image-reading centers, telemedicine is now poised to become a major source of international trade. Global investments in high-speed networks and emerging practice guidelines are providing the infrastructure. Issues such as licensure, payment mechanisms, trade protectionism and cultural biases remain; however, the potential revenue from such services could have a significant effect on worldwide trade balances.

 

In conclusion, Telemedicine is the answer to the question of solving the problem of inaccessibility to the healthcare facilities. With proper implementation it can serve multiple purposes along with the basic or specialized healthcare services. Service providers like ATT, Sprint and Verizon have provided people with the option of subscribing to health packages along with their phone plans. Recent advances in the field of information technology has improved the quality of the telemedicine services and also reduced the related costs to a great extent. However, concerns about safety of patient data, or becoming completely dependent on such services are being raised in relation to telemedicine. Nevertheless, judicious use of this health technology can save a lot more lives than before and reduce the healthcare costs to a great extent.