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Base station, mobile station, radio communication system, and communication control method

a radio communication system and base station technology, applied in the field of radio communication systems, can solve the problems of high interference between a pilot channel of a user and a pilot channel of a different user, low accuracy of channel estimation, and high frequency of channel estimation, so as to reduce the influence of characteristic degradation

Inactive Publication Date: 2010-03-18
NTT DOCOMO INC
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  • Abstract
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  • Application Information

AI Technical Summary

Benefits of technology

The present invention relates to a radio communication system, specifically a base station, mobile station, and radio communication method using a combination of a long-cycle Gold sequence and an orthogonal sequence as a reference signal for uplink. The invention also discusses the use of a constant amplitude and zero auto-correlation (CAZAC) sequence for highly-accuracy channel estimation and the problem of limited availability of unique sequences for multiple cells. The invention aims to improve the accuracy of channel estimation and reduce interference between users in a radio communication system.

Problems solved by technology

However, since the correlation properties of PN sequences are poor, the accuracy of channel estimation may become low.
In other words, the interference between a pilot channel of a user and a pilot channel of another user may become high.
Still, the CAZAC sequence has problems as described below.The number of sequences is small.
If frequency bands allocated in neighboring cells partly overlap, signals interfere with each other and their quality is reduced.

Method used

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  • Base station, mobile station, radio communication system, and communication control method
  • Base station, mobile station, radio communication system, and communication control method
  • Base station, mobile station, radio communication system, and communication control method

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Embodiment Construction

[0071]Embodiments of the present invention are described below with reference to the accompanying drawings. Throughout the accompanying drawings, the same reference numbers are used for parts having the same functions, and overlapping descriptions of those parts are omitted.

[0072]A radio communication system 1000 including mobile stations and a base station according to an embodiment of the present invention is described below with reference to FIG. 5.

[0073]The radio communication system 1000 is based on, for example, Evolved UTRA and UTRAN (also called Long Term Evolution or Super 3G). The radio communication system 1000 includes a base station (eNode B: eNB) 200 and mobile stations 100n (1001, 1002, 1003, . . . 100n; n is an integer greater than 0). The base station 200 is connected to an upper node such as an access gateway 300 and the access gateway 300 is connected to a core network 400. The mobile stations 100n are in a cell 50 and communicate with the base station 200 accordi...

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Abstract

One of sequence groups each specifying reference signal sequences for respective radio resource bandwidths is assigned to a base station and a different one of the sequence groups is assigned to a neighboring cell. The base station includes a scheduler configured to allocate radio resources; a reporting unit configured to report the allocated radio resources and a cyclic shift amount to a mobile station; and a demodulating unit configured to demodulate a signal received from the mobile station based on one of the reference signal sequences corresponding to one of the radio resource bandwidths and the cyclic shift amount. Cell reuse is applied to the reference signal sequences to be transmitted using one resource unit, and sequence hopping where different ones of the reference signal sequences are assigned to consecutive subframes is applied to the reference signal sequences to be transmitted using a bandwidth greater than one resource unit.

Description

TECHNICAL FIELD[0001]The present invention generally relates to a radio communication system. More particularly, the present invention relates to a base station, a mobile station, a radio communication system, and a communication control method.BACKGROUND ART[0002]A successor communication system to W-CDMA and HSDPA, i.e., Long Term Evolution (LTE), is currently being discussed by 3GPP, a standardization group for W-CDMA. In LTE, orthogonal frequency division multiplexing (OFDM) is to be used as a downlink radio access method and single-carrier frequency division multiple access (SC-FDMA) is to be used as an uplink radio access method (see, for example, 3GPP TR 25.814 (V7.0.0), “Physical Layer Aspects for Evolved UTRA,” June 2006).[0003]In OFDM, a frequency band is divided into multiple narrow frequency bands (subcarriers) and data are transmitted on the subcarriers. The subcarriers are densely arranged along the frequency axis such that they partly overlap each other but do not int...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): H04W72/04H04J11/00H04L27/01H04W16/10H04W72/12H04W76/02
CPCH04L5/0007H04L5/0051H04W16/02H04W16/10H04W28/16H04J13/16H04W72/042H04W88/08H04J11/005H04J13/0074H04W72/04H04W72/23H04L5/0048H04W72/1263
Inventor HIGUCHI, KENICHI
Owner NTT DOCOMO INC
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