Enabling blocks for the CMOS integration of a Multiband OFDM UWB transceiver
Italian Ministry of University and Research (MIUR)
- Department of Electronics, University of Pavia, Italy
- Department of Information Engineering, University of Pisa, Italy
- Department of Information Engineering, University of Padova, Italy
- Department of Electronics, Computer Sciences and Systems, University of Bologna, Italy
Rinaldo Castello, Department of Electonics, University of Pavia
Aim of the project
The purpose of the project is to study and design all the enabling blocks/subsystems of a high speed radio receiver for multi-band OFDM in full operation, that covers 14 bands, from 3.1GHz to 10.6GHz, providing data payload transmission capabilities from 55Mb/s up to 480Mb/s.
Being UWB a consumer product, the drive toward the reduction of cost size and power consumption is very strong to ensure commercial success. Moreover, the availability of a low cost solution for the radio makes it feasible the cost-effective implementation of more efficient and sophisticated radio transmission schemes.
D.GT actvity plan
Local coordinator / Contact
System level specifications
A first contribution of D.GT to the project is to provide initial specification to the development of circuit blocks at a block diagram level, in order to ensure compliance to the Multiband OFDM standard ECMA 368 at all stages of design.
Specifications are derived both through analysis of the standard and through system-level simulation.
Based on the results we provide guidelines for the choice of parameters in the hardware design. The aim is to obtain appropriate performance for operation at high bit rate and limited distance.
Specifications are provided in terms of:
1) sampling frequency and its precision,
2) precision of the digital representation in the A/D converter,
3) precision and stability of the carrier frequency synthesizer;
4) noise figure and gain in the amplifier;
5) required antenna impedance.
In the following months transceiver architecture and specifications will be refined for performance enhancement and/or complexity reduction, taking into account feedback and issues coming from the development of building blocks.
Receiver algorithms for the digital backend
We study the multi-band UWB approach in comparison with other technologies that use the OFDM air-interface although with smaller bandwidths, to identify the potential superiority of the multi-band UWB technology as well as the challenges it poses in terms of implementation complexity and transmit-receive signal processing algorithms. This study also allows to identify what existing solutions from the OFDM technology can be reused with limited adjustments in the Multi-band context, and what are the tasks that require novel formulations.
We then focus on the design of receiver signal processing algorithms, taking into account the constraints in terms of available resources. The tasks of packet detection, synchronization, frequecy estimation and channel estimation are considered. We study and design simplified algorithms that operate at low sampling rates and with few quantization levels. The presence of multi-user interference should also be taken into account and low complexity algorithms for multi-user interference cancellation be designed.
Antenna design and interface specifications
We characterize the antenna architectures that have the most promising performances in UWB radio system from the literature. We study key parameters such as return loss, input impedance, radiation pattern and group delay, taking also into account simplicity with respect to integration and fabrication.
Then, the chosen antenna structure is numerically simulated by means of FEM and FDTD methods in order to give design rules for novel antennas that fully meet the specifications derived. The full-wave electromagnetic analysis will be converted in a equivalent circuit model to allow the design of the matching and compensation network between the antenna terminal and the rest of the transceiver.