The IEEE 802.15

Introduction:
The IEEE 802.15 is the IEEE working group for Wireless Personal Area Networks(WPANS) and is developing standards for Personal Area Networks or short distance wireless networks consisting of portable and mobile computing devices such as PCs, Personal Digital Assistants (PDAs), peripherals, cell phones, pagers, and consumer electronics. The group has accepted significant parts of the Bluetooth specification without modification and has enriched it with various other features and considerations.


The IEEE Project 802 had successfully carried out the standardization of Ethernet, specifically, IEEE P802.3-CSMA/CD and IEEE P802.5-Token Ring. It was natural to expect this project to work on wireless networks also. The earlier work on wireless data connnectivity was centred around Working Group 11 which had been formed in 1990. The aim then was to create a Wireless Local Area Network(WLAN) standard.
In the nineties, efforts were started to get rid of a different class of wires-those connecting personal devices, computer peripherals and the like. The P802.11 was concerned with Ethernet like applications. This newly emerging set of applications was concentrated in a very localized region-that limited to a few meters around a person. Here was born the concept of personal area networks and the term WPAN.
WPAN is intended to connnect devices within the close vicinity, a few meters to state quantitatively. One or more of the group of devices connected amongst themselves may connect to the wider are networks like the LAN or the Internet as per convinience or need.Unlike LAN devices which are fixed, WPAN devices will travel. This means thatthe same standard should work everywhere- in a car, on a boat or a plane, and in different countries.Also, in today's QoS aware world, one expects some synchronous services, atleast voice, to be provided apart from data applications. All this within the lowest common denominator of the spectrum requirements around the world.
Those familiar with Bluetooth will recognize that these are some of the sameconsiderations that are handled by Bluetooth. The WPAN standardization effort started atleast an year before the public announcement of the Bluetooth atandard.


The first step in the creation of a working group at IEEE is the formation of a Study Group (SG). The SG is formed when some individuals interested in a subject are able to persuade the appropriate IEEE organization through a petition to sponsor them to explore it.Once the SG is formed, the next step is for the SG to prepare a Project Authorization Request (PAR). In this case, the SG determined that the existing 802.11 architecture, intended for LAN like applications did not suit the PAN needs well. They wanted a separate Task Group under P802.11 or a separate group at the same level as 802.11. The latter was approved and IEEE P802.15 Working Group was created on March 18, 1999.The official title for the new working group as specified in the PAR was:
STANDARD FOR Telecommunications and Information Exchange Between Systems-LAN/MAN Specific Requirements - Part 15: Wireless Medium Access Control (MAC) and Physical Layer (PHY) specifications for Wireless Personal Area Netwoks (WPANs).
The standard is meant for wireless comunication within a personal operating space (POS). The POS was fixed to a shere of 10 meters radius around a person, whether stationary or mobile. The WG's work is mainly in the PHY and MAC layers, sometimes called the Physical and Datalink layers in remembrance of the ISO OSI Reference Model.
For being granted a separate WG, the PAR made by the SG is supposed to satisfy some important criteria. These are;
Broad market potential
Distinct Identity
Technical Feasibility
Economic Feasibility
In this case, the issues of coexistence with P802.11 and electromagnetic radiation in the 2.4GHz band were also to be addressed.All the above requirements were successfully met.
The P802.15 or rather its preceding SG had initiated a call for proposals(CFP) for straw models for PHY and MAC layers. The CFP was open between May 6, 1998, March 9, 1999. The only proposal received was from the Bluetooth SIG.


When a non profit and open organisation works with independent companies, there are hudles involving copyrights, licencing arrangements and intellectual property rights to be surmounted. The Bluetooth SIG and the 802.15 WG did not want to confuse users by maintaining two non-interoperatable standards, so the Bluetooth SIG imposed certain conditions on IEEE to ensure 100% interoperability with Bluetooth 1.0 and to include the testing interfaces decided in Bluetooth 1.0 in the new WPAN standard.
To avoid errors, the applicable portions of the Bluetooth standard were poicked up on as is basis, without disturbing the sequence and flow from the original.
To enhance understanding of the document, 802 added the following sections as it does in most of its other documents:
Overview
References
Definitions
Acronyms
General Description
The structure of the main description of the standard is given in the figure below. The blue sections are lifted directly from Bluetooth, the green ones are added by P802.15.

The Protocol Implementation Conformance Statement (PICS) mentioned in the figure is a checklist of things a manufacturer must check out to ensure that his device complies to the standard.
The Service Access Point specifies the interfaces between this standard and other ISO model layers that it supports.


There are as of now, four Task Groups under P802.15. These are:
TG1: Working on WPAN standard based on Bluetooth Versions 1.x. More information available here.
TG2: This works on coexistence. The main aims are
To develop a recommended practice for an IEEE 802.15 Wireless Personal Area network that coexists with other selected wireless devices operating in unlicensed frequency bands.
To suggest modifications to other 802.15 standard(s) to enhance coexistence with other selected wireless devices operating in unlicensed frequency bands.
To suggest recommended practices for IEEE 802.11 devices to facilitate coexistence with IEEE 802.15 devices operating in unlicensed frequency bands.
More information can be found here.
TG3: This goroup aims at achieving higher data rates, exceeding 20Mbps, in WPANs. Low cost and low power operation are also to be achieved. It may be made Bluetooth compatible, in association with TG1. More information here .
TG4: This group concentrates on extremely low power operation to achieve battery lifes in months or years. Complexity must be kept low. This study aims at low data rate applications such as sensors, interactive toys, smart badges, remote controls, and home automation. More information here.
The standards these groups are aiming at should arrive shortly. They will together offer very comprehensive networking solutions for personal area networking applications.A presentation prepared by the WPAN.