ZL10353

Data Sheet

10

Zarlink Semiconductor Inc.

2.9

Common Phase Error Correction

This module subtracts the common phase offset from all the carriers of the OFDM signal to minimize the effect of

the tuner phase noise on system performance.

2.10

Channel Equalization

This consists of two parts. The first part involves estimating the channel frequency response from pilot information.

Efficient algorithms have been used to track time-varying channels with a minimum of hardware.

The second part involves applying a correction to the data carriers based on the estimated frequency response of

the channel. This module also generates dynamic channel state information (CSI) for every carrier in every symbol.

2.11

Impulse Filtering

ZL10353 contains several mechanisms to reduce the impact of impulse noise on system performance.

2.12

Transmission Parameter Signalling (TPS)

An OFDM frame consists of 68 symbols and a superframe is made up of four such frames. There is a set of TPS

carriers in every symbol and all these carry one bit of TPS. These bits, when combined, include information about

the transmission mode, guard ratio, constellation, hierarchy and code rate, as defined in ETS 300 744. In addition,

the first eight bits of the cell identifier are contained in even frames and the second eight bits of the cell identifier are

in odd frames. The TPS module extracts all the TPS data, and presents these to the host processor in a structured

manner.

2.13

De-Mapper

This module generates soft decisions for demodulated bits using the channel-equalized in-phase and quadrature

components of the data carriers as well as per-carrier channel state information (CSI). The de-mapping algorithm

depends on the constellation (QPSK, 16QAM or 64QAM) and the hierarchy (

α = 0, 1, 2 or 4). Soft decisions for both

low- and high-priority data streams are generated.

2.14

Symbol and Bit De-Interleaving

The OFDM transmitter interleaves the bits within each carrier and also the carriers within each symbol. The

de-interleaver modules consist largely of memory to invert these interleaving functions and present the soft

decisions to the FEC in the original order.