IEEE 802.21
The IEEE 802.21 refers to Media Independent Handoff (MIH) and is an
The IEEE 802.21 working group started work in March 2004. More than 30 companies have joined the working group. The group produced a first draft of the standard including the protocol definition in May 2005. The standard was published in January 2009.
Reasons for 802.21
Cellular networks and 802.11 networks employ handover mechanisms for handover within the same network type (aka horizontal handover). Mobile IP provides handover mechanisms for handover across subnets of different types of networks, but can be slow in the process. Current 802 standards do not support handover between different types of networks. They also do not provide triggers or other services to accelerate mobile IP-based handovers. Moreover, existing 802 standards provide mechanisms for detecting and selecting network access points, but do not allow for detection and selection of network access points in a way that is independent of the network type.
Some of the expectations
- Allow 3G cellular networks.
- Allow users to engage in teleconferencing.
- Apply to both wired and wireless networks, likely the same list as IEEE P1905 specifies to cooperate in software-defined networking (see also OpenFlow)
- Allow for use by multiple vendors and users.
- Compatibility and conformance with other 802.11sad hoc wireless mesh networking.
- Compatibility and conformance with other
- Include definitions for managed objects that are compatible with management standards like SNMP.
- Although security protocols will not be defined in the standard, authentication, authorization, and network detection and selectionwill be supported by the protocol.
Implementation and Issues
Implementation is still in progress. Current technologies such as 802.11 that accomplish handover use software to accomplish handovers and suggest that software will also be the way that handover will be implemented by 802.21. The use of software as a means to implement 802.21 should not cause large increases in the cost of networking devices. An open-source software implementation is provided by ODTONE.[citation needed]
Crossing different administrative connectivity domains will require agreements among different network operators. Currently, such agreements are still not in place. In smartphones today, a user can manually select to use WiFi or cellular LTE, but the connections are not automatically maintained should a disconnection of one network occurs.
Hence, seamless handovers across different wire/wireless networks are still not available today.
Examples
- A user should be able to unplug from an 802.3 network and get handed off to an 802.11 network.
- A cellular phone user during a call should be able to enter an 802.11 network hotspot and be seamlessly handed off from a GSMnetwork to the 802.11 networks and back again when leaving the hotspot.
Other similar technologies
The
See also
- Mobility management
- Mobile IP
- Handover
- Radio resource management
- Roaming
- Vertical handoff
- Handoffs in Wireless ATM / Mobile ATM Asynchronous Transfer Mode#Wireless ATM or mobile ATM
References
External links
- IEEE Standards Associations
- IEEE 802.21 web site
- Is Cellular Handoff Nigh? article
- Internet Protocol Journal Introduction to IEEE 802.21
- Open source implementation ODTONE