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Time alignment in multicarrier systems

  • US 8,391,129 B2
  • Filed: 07/24/2012
  • Issued: 03/05/2013
  • Est. Priority Date: 07/25/2011
  • Status: Active Grant
First Claim
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1. A method comprising:

  • a) receiving, by a wireless device, at least one radio resource control message from a base station, said at least one radio resource control message;

    i) a causing configuration of a plurality of carriers comprising a first carrier and at least one second carrier; and

    ii) comprising;

    (1) a carrier group index for a second carrier in said at least one second carrier, said carrier group index identifying a second carrier group, said second carrier group being one of a plurality of carrier groups, said second carrier group comprising a second subset of said at least one second carrier;

    (2) a plurality of second uplink carrier parameters of a second uplink carrier for said second carrier; and

    (3) a plurality of random access resource parameters identifying random access resources for said second carrier;

    b) receiving, by said wireless device, a media access control activation command for at least activating said second carrier in said second carrier group;

    c) receiving, by said wireless device from said base station, a control command causing said wireless device to transmit a random access preamble on said second uplink carrier, said control command comprising a preamble index corresponding to said random access preamble;

    d) transmitting, by said wireless device, said random access preamble on said random access resources on said second uplink carrier, transmission timing of said random access preamble being determined, at least in part, employing a second synchronization signal transmitted on one of at least one downlink carrier in said second carrier group, uplink transmissions in said second carrier group employing said second synchronization signal as timing reference;

    e) receiving, by said wireless device, at least one time alignment command from said base station, said time alignment command comprising;

    i) a time adjustment value; and

    ii) an index identifying said second carrier group; and

    f) applying, by said wireless device, said time adjustment value to uplink signals transmitted on all activated uplink carriers in said second carrier group such that said base station receives substantially aligned uplink signals in frames and subframes of said second carrier group.

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