Skip to content

Evolution of IEEE 802.16 family of standard

June 29, 2010

At the end of the twentieth century many telecommunication equipment manufacturers began to build up and present products for BWA. But the industry was undergoing for an interoperable standard. With that need the national Wireless Electronics Systems Testbed (N-WEST) of the U.S National Institute of Standards and Technology (NIST) called a meeting to talk about the topic in August 1998. The meeting ended up with a decision to organize within IEEE 802. This led to formation of the 802.16 Working Group. Since then, the Working Group members have been working a lot for the development of fixed and mobile BWA standards. IEEE Working Group 802.16 on Broadband Wireless Access (BWA) standard is responsible for development of 802.16 and the included WirelessMan air interface, along with associated standards and amendments.

The IEEE 802.16 standard contains the specification of Physical (PHY) and Medium Access Control (MAC) layer for BWA. The first version of the standard IEEE 802.16-2001 was approved on December 2001 and gone through many amendments to organize with new features and functionalities. On September 2004, the current version of the standard IEEE 802.16-2004 approved and combined all the previous versions of the standards. This standard specifies the air interface for fixed BWA systems in license and licensed exempt spectrum supporting multimedia services. The Working Group approved the amendment IEEE 802.16e-2005  on February 2006. The evolution of the standard 802.16 is presented shortly below.

IEEE 802.16-2001

To provide fixed broadband wireless access in a point-to-point (PTP) or point-to-multipoint (PMP) topology this issue specifies a set of MAC and PHY layer standards. The PHY layer uses single carrier modulation in 10-66 GHz frequency range. Base Station (BS) assigned transmission times, durations and modulations, shared with all nodes in the network in the form of broadcast Uplink and Downlink maps. Subscribers hear only the base station that they are connected to and do not need to listen any other node of the network. Subscriber Stations (SS) have the ability to negotiate for bandwidth allocation on a burst to burst basis to provide scheduling flexibility.

The modulation schemes which employed in this standard are QPSK, 16-QAM and 64-QAM. These can be changed from frame to frame and SS to SS, depending on the robustness of the connection. The standard supports both Time Division Duplexing (TDD) and Frequency Division Duplexing (FDD).

The ability of providing differential Quality of Service (QoS) in the MAC Layer is an important feature of 802.16-2001. QoS check performed by a Service Flow ID. Service flows can be originated either from BS or SS. 802.16-2001 works only in (Near) Line of Sight (LOS) conditions with outdoor Customer Premises Equipment (CPE).

IEEE 802.16c-2002

IEEE Standards Board approved amendment IEEE 802.16c on December 2002. The detail system profiles for 10-66 GHz were added and some errors and irregularities of the first version of the standard were corrected in this amendment.

IEEE 802.16a-2003

This version amends IEEE 802.16-2001 by changing some characteristics. It enhances the medium access control layer so that it can support multiple physical layer specifications and providing additional physical layer specifications. IEEE 802.16 working group ratified this in January 2003. 2-11 GHz physical layer support was added in this amendment. Both licensed and license-exempt bands are included. As it operates below 11 GHz range, Non Line of Sight (NLOS) operation becomes possible which extends the geographical reach of the network. Multipath propagation becomes an issue due to NLOS operation. Multipath propagation, interference mitigation, advanced power management technique and adaptive antenna arrays were included in specification. Orthogonal Frequency Division Multiplexing (OFDM) inclusion was an alternative option to single carrier modulation. This version also improved Security issue. Some privacy layer features became obligatory while in 802.16-2001 they were optional. Mesh topology with PMP was an optional support in this version of IEEE802.16a.

Table: Comparison of IEEE 802.16 BWA Standard

IEEE 802.16-2001 IEEE 802.16a IEEE 802.16-2004 IEEE 802.16e-2005
Completed December 2001 January 2003 September 2004 December 2005
Spectrum 10-66 GHz 2-11 GHz 2-11 GHz 2-11 GHz
Propagation/Channel

Conditions

LOS NLOS NLOS NLOS
Bit Rate UP to 134 Mbps

(28 MHz

Channelization)

UP to 75 Mbps

(20 MHz

Channelization)

UP to 75 Mbps

(20 MHz

Channelization)

UP to 15 Mbps

(5 MHz

Channelization)

Modulation QPSK, 16-QAM

(optional in UL),

64-QAM

(optional)

BPSK, QPSK,

16-QAM,

64-QAM,

256-QAM

(optional)

256 subcarriers

OFDM, BPSK,

QPSK, 16-QAM,

64-QAM, 256-QAM

Scalable

OFDMA, QPSK,

16-QAM, 64-QAM, 256-QAM

(optional)

Mobility Fixed Fixed Fixed/Nomadic Portable/mobile

IEEE 802.16-2004

802.16-2001, 802.16c-2002 and 801.16a-2003 were integrated all together and a new standard created which is known as 802.16-2004. In the beginning, it was published as a revision of the standard under the name 802.16REVd, but the standard was reissued under the name 802.16-2004 at September 2004. This is the version of the standard which is used for WiMAX certification.

Advertisements
Leave a Comment

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: