LTE, LTE-Advanced and WiMAX: Towards IMT-Advanced Networks

Frame Structure in IEEE 802.16-2009

The smallest unit of resources in IEEE 802.16 is the slot, which can be allocated to a single user. Each slot consist of one subchannel utilizing one, two, or three OFDM symbols, depending on the type of subchannelization used. The standard defines the following four subchannelization types:

• DL Full Usage of SubCarriers (FUSC): Each slot constitutes one subchannel by one OFDM symbol. A single subchannel consists of 48 subcarriers that are not necessarily contiguous;
• DL Partial Usage of Subcarriers (PUSC): Each slot constitutes one subchannel by two OFDM symbols. One subchannel consists of 24 data subcarriers grouped in two clusters;
• UL PUSC and Tile Usage of Subcarriers (TUSC): Each slot constitutes 16 subcarriers by three OFDM symbols; and
• Band AMC: UL and DL contiguous subcarrier permutation. Each slot consists of either eight, 16 or 24 subcarriers by respectively six, three, or two OFDM symbols.

A frame comprises slots in both time and frequency. In the frequency domain, a frame is divided into segments; while in the time domain 6, it is divided into zones. Different frame durations (2.5, 4, 5, 8, 10, 12.5, and 20 ms) are supported; each consisting of a fixed number of slots. Once the network operates with a particular frame duration, it should not be changed as otherwise resynchronization would be required between all network elements. Adjacent slot groups are assigned to users based on their overall demand, individual QoS and traffic requirements, ...