BASE STATION APPARATUS, USER APPARATUS, AND METHOD USED IN MOBILE COMMUNICATIONS SYSTEM

• US 20100103890A1
• Filed: 03/17/2008
• Published: 04/29/2010
• Est. Priority Date: 03/20/2007
• Status: Active Grant

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Kishiyama, Yoshihisa, Sawahashi, Mamoru, Higuchi, Kenichi, Ishii, Hiroyuki
• Granted Patent: US 8,462,711 B2
• Time in Patent Office: Days
• US Class Current: 370/329
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 27/26134 Pilot insertion in the transmitter chain, e.g. pilot overlapping with data, insertion in time or frequency domain
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0044 allocation of payload
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/005 of common pilots, i.e. pilots destined for multiple users or terminals

Abstract

A base station apparatus in a mobile communications system which uses orthogonal frequency division multiplexing (OFDM) for downlink is disclosed. The base station includes a unit which generates a first signal; a unit which generates a second signal; a unit which multiplexes the first signal and the second signal to map the multiplexed signals to a sub-carrier to generate a transmit symbol; and a mapping determining unit which determines a position of mapping the second signal to the sub-carrier, wherein the mapping determining unit determines the mapping position based on a cell ID or cell group ID, and a mapping pattern defined with a sequence having two-stage structure.

Claims

1. A base station apparatus in a mobile communications system which uses orthogonal frequency division multiplexing (OFDM) for downlink, comprising:

a unit which generates a first signal;

a unit which generates a second signal;

a unit which multiplexes the first signal and the second signal to map the multiplexed signals to a sub-carrier to generate a transmit symbol; and

a mapping determining unit which determines a position of mapping the second signal to the sub-carrier, wherein the mapping determining unit determines the mapping position based on a cell ID or cell group ID, and a mapping pattern defined with a sequence having a two-stage structure.

2. The base station apparatus as claimed in claim 1, wherein

the first signal is a data signal including user data or control data, and the second signal is a reference signal.

3. The base station apparatus as claimed in claim 1, wherein

the mapping pattern defined with the sequence having the two-stage structure is defined by a first-layer sequence including a random hopping pattern and a second-layer sequence representing a shift having a fixed shift amount.

4. The base station apparatus as claimed in claim 3, wherein

the random hopping pattern has an amount of hopping between sub-frames that is not more than a predetermined threshold value.

5. A user apparatus in a mobile communications system which uses orthogonal frequency division multiplexing (OFDM) for downlink, comprising:

a unit which Fourier transforms a signal received from a base station apparatus, and derives a receive symbol;

a unit which separates a first signal and a second signal from the receive symbol;

a mapping information managing unit which determines information on mapping of the second signal on a sub-carrier, and supplies the mapping information to the separating unit; and

a unit which makes channel estimation using the second signal, and demodulates the first signal, wherein

the mapping information managing unit stores in advance a corresponding relationship between a cell ID or cell group ID and a mapping pattern defined in a two-stage sequence, detects the mapping pattern based on the cell ID of a cell in which the user apparatus is located or the cell group ID of a cell group to which the cell belongs, and supplies the detected mapping pattern to the separating unit.

6. The user apparatus as claimed in claim 5, wherein

the first signal is a data signal including user data or control data, and the second signal is a reference signal.

7. The user apparatus as claimed in claim 5, wherein

the mapping pattern defined in the two-stage sequence is defined by a first-layer sequence including a random hopping pattern and a second-layer sequence representing a shift having a fixed amount of shift.

8. The user apparatus as claimed in claim 7, wherein

the random hopping pattern has an amount of hopping between sub-frames that is not more than a predetermined threshold value.

9. A method of mapping to a sub-carrier of a signal in a mobile communications system which uses orthogonal frequency division multiplexing (OFDM) for downlink, comprising the step of mapping, when a first signal and a second signal are multiplexed, the multiplexed signals to the sub-carrier to generate a transmit symbol in a base station apparatus, the second signal to a sub-carrier position which is determined by a cell ID or cell group ID, and a mapping pattern defined in a two-stage sequence including a first sequence having a random hopping pattern and a second sequence having a shift with a fixed shift amount.

10. The method of mapping as claimed in claim 9, wherein the mapping pattern is defined as a sum of a first function which is associated with the cell ID or cell group ID to define the random hopping pattern sequence, and a second function which is associated with the cell ID or the cell group ID to define the sequence of the shift pattern with the fixed shift amount.

11. The method of mapping as claimed in claim 9, wherein the cell or cell group having the same hopping pattern is arranged in a neighboring manner in the first sequence.