Nokia Mobile Phones Limited

Ilkka J Niva

Stash F Czaja

Sakari Jorri

Mika Jari Tuutijarvi

Jim Robertson

A method and system for mobile assisted handoff between base stations using different carrier frequencies in a Code Division Multiple Access (CDMA) cellular system. In the method and apparatus, a mobile station performs handoff measurements on forward link transmissions of handoff candidate CDMA base stations, where the forward link transmissions are transmitted on a carrier frequency that differs from the forward link carrier frequency of the current base station. The handoff measurements are performed during selected transmission frames that define transmission periods on the reverse link by the mobile station. During the measurement time in the selected transmission frame, the mobile station does not receive (punctures) data sent to it on the forward link and does not transmit data on the reverse link.

Mobile station handoff between different CDMA frequencies

A method and system for mobile assisted hand-off between base stations using different carrier frequencies in a Code Division Multiple Access (CDMA) cellular system. In the method and apparatus, a mobile station performs handoff measurements on forward link transmissions of handoff candidate CDMA base stations, where the forward link transmissions are transmitted on a carrier frequency that differs from the forward link carrier frequency of the current base station. The handoff measurements are performed during selected transmission frames that define transmission periods on the reverse link by the mobile station. During the measurement time in the selected transmission frame, the mobile station does not receive (punctures) data sent to it on the forward link, and does not transmit data on the reverse link.

Mobile assisted hard hand-off for a code division multiple access (CDMA)

This invention teaches a method, and circuits that operate in accordance with the method, for decoding data received from a communications channel. The method includes the steps of: (a) receiving a modulated communications signal that conveys block encoded data having at least a data field and a syndrome data field; and (b) determining transition metrics and path metrics for the block encoded data. The step of determining path metrics includes a step of retaining path metrics only for a Maximum-Likelihood (ML) path and for a second best ML path. The method further includes a step of: (c) decoding the block encoded data by performing either a full or a partial traceback operation for both the ML path metrics and also for the second best ML path metrics. In a full traceback there is obtained from the ML path a first plurality of detected bits representing the data field, a second plurality of detected bits from the ML path representing the syndrome data field, a third plurality of detected bits from the second best ML path representing the data field, and a fourth plurality of detected bits from the second best ML path representing the syndrome data field. A next step (d) determines a syndrome from the first plurality of detected bits, and then compares the determined syndrome to the second plurality of detected bits. Upon a match a next step (e) outputs the first plurality of detected bits as a received frame of data. If the step of comparing the determined syndrome to the second plurality of detected bits does not indicate a match, the method instead: (f) determines a syndrome from the third plurality of detected bits; (g) compares the determined syndrome to the fourth plurality of detected bits and, upon a match, (h) outputs the third plurality of detected bits as a received frame of data.

Viterbi decoder with l=2 best decoding paths

A method, and apparatus for accomplishing the method, that causes the power of a narrow bandwidth signal to be spread to a wider bandwidth. The method operates by modulating the power of the spectral components that are located close to a carrier frequency. This reduces the DC component of a base band signal and correspondingly reduces the charging of a AC coupling capacitors in the base band circuitry. As a result, receiver recovery time is increased, and a more accurate signal strength estimate is made by a mobile telephone. In one embodiment of the invention a local oscillator signal (LO1) for an IF stage is first offset from a nominal frequency for an RF channel to be measured, and is then subsequently made equal to the nominal frequency. The variation in LO1 introduces phase noise which results in the modulation of the base band signal.

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Suunnistajantie, Finland

Ilkka J Niva