Methods and apparatus for random access in multi-carrier communication systems
View Patent ↗Methods and apparatus in a multi-carrier cellular wireless network with random access improve receiving reliability and reduce interference of uplink signals of a random access, while improving the detection performance of a base station receiver by employing specifically configured ranging signals.
1. A method for signal transmission by a mobile station in a cell in an orthogonal frequency division multiple access (OFDMA) cellular system, the method comprising:
transmitting a ranging signal containing a full ranging sequence in a ranging time slot containing multiple Orthogonal Frequency Division Multiplexing (OFDM) symbols, wherein:
the full ranging sequence is composed of multiple concatenated shorter sequence segments, each sequence segment of the full ranging sequence being carried on a block of contiguous subcarriers in an OFDM symbol in the multiple-OFDM-symbol ranging time slot; and
the full ranging sequence is segment-wise orthogonal to other full ranging sequences used in the cell containing the mobile station; and
transmitting data over a data subchannel.
2. The method of claim 1 , wherein each sequence segment of the full ranging sequence is a Hadamard sequence.
3. The method of claim 1 , wherein the full ranging sequence is a non-binary sequence.
4. The method of claim 1 , wherein different cells have different blocks of subcarrier configurations.
5. The method of claim 1 , wherein the number of multiple concatenated shorter sequence segments is four.
6. The method of claim 1 , further comprising controlling a power level for the transmission of the full ranging sequence using an open-loop power control scheme.
7. A mobile station in a cell in an orthogonal frequency division multiple access (OFDMA) cellular system, the mobile station comprising a transmitter configured to transmit:
a ranging signal containing a full ranging sequence in a ranging time slot containing multiple Orthogonal Frequency Division Multiplexing (OFDM) symbols, wherein:
the full ranging sequence is composed of multiple concatenated shorter sequence segments, each sequence segment of the full ranging sequence being carried on a block of contiguous subcarriers in an OFDM symbol in the multiple-OFDM-symbol ranging time slot; and
the full ranging sequence is segment-wise orthogonal to other full ranging sequences used in the cell containing the mobile station; and
data over a data subchannel.
8. The mobile station of claim 7 , wherein each sequence segment of the full ranging sequence is a Hadamard sequence.
9. The mobile station of claim 7 , wherein the full ranging sequence is a non-binary sequence.
10. The mobile station of claim 7 , wherein different cells have different blocks of subcarrier configurations.
11. The mobile station of claim 7 , wherein the number of multiple concatenated shorter sequence segments is four.
12. The mobile station of claim 7 , further comprising a controller configured to control a transmission power level of the full ranging sequence using an open-loop power control scheme.