RFIntroduction to WiMAX Advanced (IEEE 802.16m)
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The WiMAX Forum publishes various WiMAX standards as the 802.16 series of IEEE standards. WiMAX stands for Worldwide Inter-operability for Microwave Access. It’s designed to provide both fixed and mobile broadband wireless connectivity.
Different versions of the WiMAX standard exist, including WiBro (used in Korea), Fixed WiMAX (802.16d), and Mobile WiMAX (802.16e). Fixed WiMAX uses OFDM modulation, while Mobile WiMAX uses OFDMA. See the comparison between OFDM and OFDMA to understand their differences. The IEEE 802.16m standard is also known as WiMAX Advanced.
IEEE 802.16m Basics
802.16 is a series of Wireless Broadband standards developed by the IEEE for Wireless Metropolitan Area Networks. These standards are also called ‘WiMAX’ (Worldwide Interoperability for Microwave Access) by the WiMAX Forum.
WiMAX falls into two main categories:
- Fixed WiMAX: Based on the OFDM Physical layer and MAC layer defined in the standard.
- Mobile WiMAX: Based on OFDMA PHY/MAC.
The WiMAX Forum promotes and certifies the compatibility and interoperability of products based on approved, published specifications. Products based on the 802.16e-2005 standard are deployed globally and are popularly known as Mobile WiMAX.
802.16m is the successor to 802.16e-2005 and is commonly referred to as Mobile WiMAX Release 2 or WirelessMAN-Advanced. It has been approved by ITU-R as an IMT-Advanced technology.
802.16m Features
Practically speaking, with 4x2 MIMO, a 20MHz bandwidth, and TDD topology, 802.16m supports 120 Mbps in the downlink and 60 Mbps in the uplink per site simultaneously.
802.16m will operate in both TDD and FDD modes, accommodating a wide range of spectrum availability globally. The channel bandwidths are targeted up to 20MHz and possibly 40MHz channels. In these higher channels, OFDMA becomes extremely capable compared to other technologies in terms of capacity and performance.
- 802.16e (20MHz sector): Peak data rate in the downlink is 128 Mbps.
- 802.16m (20MHz sector): Peak data rate in the downlink is around 350 Mbps.
- 802.16e: Uplink per sector is 28 Mbps.
- 802.16m: Uplink per sector is 200 Mbps.
Mobility in 802.16e is 60 to 120 km/h, while in 802.16m it will be up to 350 km/h. This makes WiMAX technology more efficient for sensitive VoIP services, with latency of less than 10ms and hand-off times of 20ms.
The following table details the features of 802.16m (WiMAX Advanced):
| Specifications | WiMAX Advanced |
|---|---|
| RF Carrier Frequency | Under 6 GHz |
| Bandwidth | 5 to 20 MHz |
| Antenna Configuration | Downlink >= 2 T X 2 R |
| Uplink > = 1T X 2R | |
| Topology | Full duplex FDD, Half duplex FDD, TDD |
The key differences between WiMAX and WiMAX Advanced systems are:
- WiMAX (16d) does not support advanced antenna system concepts such as MIMO and beamforming, while WiMAX Advanced does.
- Data rate and coverage are higher in WiMAX Advanced compared to WiMAX.
802.16m References
The 802.16m-2011 standard can be downloaded from the IEEE website.
