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Methods and Means for Embedding Information Content in the Pilot Symbols of Wireless CDMA Systems

IP.com Disclosure Number: IPCOM000011785D
Original Publication Date: 2003-Mar-14
Included in the Prior Art Database: 2003-Mar-14
Document File: 3 page(s) / 76K

Publishing Venue

Motorola

Related People

S. Fontenelle: AUTHOR [+3]

Abstract

Wireless CDMA systems are composed of data-based and control-based physical channels. Control-based information is used to improve the radio link quality and includes for example pilot and power control fields… Enough control information must be available without sacrificing reliability of its transmission or amount of data information to be delivered. Such signalling is often quite limited and further resource to transmit additional information would improve the performance of the overall system. In this article a method is proposed to use control fields, and in particular ‘Pilot’ fields, to embed additional feedback and/or control information. Such a method can be used for both uplink and/or downlink transmissions.

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Methods and Means for Embedding Information Content

in the Pilot Symbols of Wireless CDMA Systems

by S. Fontenelle, M. Fratti, S. Buljore

Abstract

Wireless CDMA systems are composed of data-based and control-based physical channels. Control-based information is used to improve the radio link quality and includes for example pilot and power control fields… Enough control information must be available without sacrificing reliability of its transmission or amount of data information to be delivered. Such signalling is often quite limited and further resource to transmit additional information would improve the performance of the overall system. In this article a method is proposed to use control fields, and in particular ‘Pilot’ fields, to embed additional feedback and/or control information. Such a method can be used for both uplink and/or downlink transmissions.

Problem(s) To Be Solved

CDMA systems have data-based and control-based physical channels. Control-based information is used to improve the radio link quality and includes, for example, pilot, power control, ‘Transport Format Control Indication’ (cf. UMTS) fields… Data and control information are usually multiplexed on dedicated physical channels. This multiplexing can be done in the time-, frequency-, space- or code-domain (i.e., dedicating different spreading codes for data or control information). No matter what multiplexing method is used, a certain number of symbols is dedicated to the transmission of control information. Enough control information must be available without sacrificing reliability of its transmission or amount of data information to be delivered. Indeed usually, few such control symbols can be afforded, in order to:

1.       maintain a high spreading factor for high reliability of transmission;

2.       avoid to sacrifice data symbols.  

Such constraints contrast with the need of transmitting more and more control symbols, in order to optimize radio links that rely on increasingly sophisticated techniques (e.g., Multiple Transmitters Multiple Receivers techniques).

Indeed, in CDMA systems such as UMTS FDD system, feedback signalling or control information is required in order to define for example the power control command or the weights to be applied in transmission when Transmit Adaptive Array (TxAA) is considered. Such signalling is quite limited and further resource to transmit additional information would improve the performance of the overall system. Known technologies usually try to balance above constraints 1 and 2 with the need of increasing the number of control symbols. No known technology tries to exploit the nature of the ‘Pilot’ control symbols: indeed such ‘Pilot’ symbols are un-modulated (i.e., they do not carry any information, or, their value is known a priori at the receiver side) and are used for some specific operations like radio channel estimation. On the other hand, the modulation of all the ‘Pilot’ control symbols results in po...