Nec Corporation

Akihisa Ushirokawa

Shousei Yoshida

Kojiro Hamabe

Kazuhiro Okanoue

Hiroshi Furukawa

Naoto Ishii

Yasushi Maruta

Hironori Mizuguchi

Yoshikazu Kakura

Jinsock Lee

Kengo Oketani

Yukitsuna Furuya

Ichiro Tsujimoto

Koichi Tamura

Nahoko Kuroda

Masayuki Kimata

Nahoko Takano

Hideho Tomita

Shuzo Yanagi

Shingo Kikuchi

Akira Hioki

Shosei Yoshida

In a pilot signal transmission method for raising the SIR measurement accuracy for transmission power control during high-speed transmission and thus reducing the block error rate and improving the throughput, a first SIR value measured by first pilot signals and second SIR value measured by second pilot signals are first compared, and the presence or absence of second pilot signals then determined in slot units based on the comparison results. When the second pilot signals exist, the second pilot signals are used in addition to the first pilot signals in the SIR measurement for high-speed closed-loop transmission power control. When the second pilot signals do not exist, only the first pilot signals are used in the SIR measurement for high-speed closed-loop transmission power control.

Pilot signal transmission method and radio communication system for enabling measurement of reception quality with high accuracy

In the communication system performing transmission with generating the vacant period in the slotted mode during data transmission in order to perform various process, such as different frequency carrier quality measurement or so forth, the control signal for maintaining a communication quality is inserted even in the vacant period. Therefor, a link quality may not be degraded even if the vacant period is long. Namely, when the pilot signal is used as the control signal, even in the vacant period, measurement of the link quality of the forward link with the pilot signal is performed in the mobile station to report the result of measurement to the base station. Therefore, transmission power control of the forward link can be performed according to the report in the base station. Therefore, degradation of the forward link can be eliminated.

Mobile communication system, communication control method, and base station and mobile station to be employed in the same

In the communication system performing transmission with generating the vacant period in the slotted mode during data transmission in order to perform various process, such as different frequency carrier quality measurement or so forth, the control signal for maintaining a communication quality is inserted even in the vacant period. Therefore, a link quality may not be degraded even if the vacant period is long. Namely, when the pilot signal is used as the control signal, even in the vacant period, measurement of the link quality of the forward link with the pilot signal is performed in the mobile station to report the result of measurement to the base station. Therefore, transmission power control of the forward link can be performed according to the report in the base station. Therefore, degradation of the forward link can be eliminated.

An FDD/CDMA transmission/reception system includes a CDMA transmitter and a CDMA receiver. The CDMA transmitter includes a plurality of transmission antennas, signal transmission units for transmitting transmission signals weighted by different values to the respective transmission antennas, and pilot signal transmission units for transmitting a plurality of different pilot signals to the respective transmission antennas. The CDMA receiver includes a reception unit for obtaining one received signal from the transmission signals from the plurality of transmission antennas of the CDMA transmitter in consideration of reception quality, and a unit for transmitting antenna control signals corresponding to reception power values of the received pilot signals to the CDMA transmitter.

FDD/CDMA transmission/reception system

To provide a cellular system for enhancing precision of judgement by rendering the number of code words to be judgement candidates at a base station as small as possible and thus improving the efficiency of using the code words. A base station control unit notifies the base station of the maximum number of the base stations on which a mobile station may set up links to allow the base station to limit the code word judgement candidates that may be received. Accordingly, it is possible to increase the distance between the codes among the code words to be the judgement candidates, consequently allowing the base station to reduce judgement errors of the code word.

Cellular system and base station specification method in CDMA mode

FDD/CDMA receiver having transmission antenna control circuit

A radio communication system for quickly selecting an optimum transmission mode in accordance with the quality and situation of a propagation path is provided. The system comprises first and second radio communication apparatuses capable of radio-communicating with each other. The first radio communication apparatus comprises a propagation path environment estimator for outputting the estimation result as propagation path environment information, a propagation path quality estimator for outputting the estimation result as propagation path quality, and a transmitter for transmitting both the informations to the second radio communication apparatus. The second radio communication apparatus comprises a transmission mode selector for selecting one of the transmission modes used for communicating with the first radio communication.

Radio communication system and transmission mode selecting method

A spread code allocation method in a CDMA cellular having a first code set including a plurality of first codes and a second code set including one or a plurality of second codes, allocating the second code to the first code set and multiplying the plurality of first codes by the allocated second code to generate a plurality of combined codes, assigning a priority to the combined code for each transmission signal to be transmitted from a base station to a mobile station, allocating the combined code to the transmission signal based on the priority, and diffusing the transmission signal by the allocated combined code to transmit the diffused transmission signal to the mobile station.

Spread code allocation method and base station in CDMA cellular

A path timing comparing section compares correlation peak values and their path timings detected from a delay profile with correlation peak values and their path timings assigned to fingers in the previous cycle. If a path timing determining section determines from the comparison result that a path with high intensity level has appeared, it immediately assigns the path to a finger. This enables maintaining good receiving characteristics.

Demodulation apparatus and demodulation method for mobile communication

To prevent degradation of transmission quality due to interference between scramble codes, under such a situation as soft hand over, when the number of mobile stations connected with a base station exceeds the number of the orthogonal codes. The base station decides the priority of the scramble code. The scramble code is allocated to the mobile station, in accordance with the priority. When a mobile station ends its call, or stops temporarily its call, its PN code is re-allocated to the mobile station with lowest priority code.

Method and base station for allocating pseudo noise code

A CDMA adaptive antenna receiving apparatus is provided with plural receivers of which each is for receiving one or more of desired signal components incoming at the same time. Each of the plural receivers includes plural adaptive receiving units for updating sequentially a directivity in accordance with one desired signal component. The plural adaptive receiving units which are included in the same receiver employ a symbol decision error of the same receiver in common. Each receiver further includes a means for detecting the incoming directions of the plural desired signal components and a means for controlling directivities of the plural adaptive receiving units in accordance with the incoming directions of the plural desired signal components and directivities of the plural adaptive receiving units.

CDMA adaptive antenna receiving apparatus and communication system

The adaptive receiving block for the k-user generates a receiving signal by the k-th user the m-th path inherent antenna directivity pattern respectively, obtains the k-th user demodulation signal by demodulating and adding for each path simultaneously and outputs weight control error signal e&prime; &tilde;e&prime; for the purpose of forming directivity pattern for each path. The weight control error synthesis circuit optionally synthesizes weight control error signal e&prime; &tilde;e&prime; and outputs synthesis weight control error signal e&prime; &tilde;e&prime; . Synthesizing weight control error signals with respect to paths whose arrival directions of multi-path of each user are close, performing a control without synthesizing weight control errors with respect to paths whose arrival directions are apart, increasing the information available for adaptive control and enhancing an adaptive control characteristic and an interference suppression ability.

Adaptive receiving device removing interference from users and multi-paths by antenna directivity control

An adaptive antenna receiving apparatus includes (a) a plurality of antennas, (b) a plurality of adaptive receivers each of which receives signals received in the antennas, in an adaptive antenna pattern in an order in which the signals arrived at the antennas, (c) a plurality of initial receipt weight calculators each of which calculates an initial antenna pattern for each of the signals, and outputs the thus calculated initial antenna pattern to each of the adaptive receivers, (d) an adder which adds output signals transmitted from each of the adaptive receivers, to one another, and (e) a judge which symbol-judges an output signal transmitted from the adder, and transmits an output signal to each of the adaptive receivers.

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Tokyo, Japan

Akihisa Ushirokawa