Spread spectrum communication device and spread spectrum communication method

• US 6,671,267 B1
• Filed: 02/14/2000
• Issued: 12/30/2003
• Est. Priority Date: 03/26/1998
• Status: Expired due to Term

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Murai, Hideshi, Yano, Yasuhiro
• Primary Examiner(s): Nguyen, Steven
• Assistant Examiner(s): PHAN, MAN U
• Application Number:
  US09/424,611
• Time in Patent Office: 1,415 Days
• Field of Search: 370/331, 370/342, 370/335, 370/441, 370/468, 370/491, 370/500, 370/320, 370/465, 370/529, 370/479, 375/285, 375/296, 375/267, 375/259, 455/436, 455/437, 455/439, 455/443
• US Class Current: 370/342
• CPC Class Codes: G08C 15/00 Arrangements characterised by the use of multiplexing for the transmission of a plurality of signals over a common path
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 1/70735 Code identification H04B1/7083 takes precedence
• CPC Class Codes: H04B 1/7075 with code phase acquisition
• CPC Class Codes: H04B 1/7083 Cell search, e.g. using a three-step approach
• CPC Class Codes: H04B 1/7087 Carrier synchronisation aspects
• CPC Class Codes: H04B 2201/70703 using multiple or variable rates
• CPC Class Codes: H04B 7/2628 using code-division multiple access [CDMA] or spread spectrum multiple access [SSMA] H04B7/2618 takes precedence
• CPC Class Codes: H04B 7/2668 Arrangements for Wireless Code-Division Multiple Access [CDMA] System Synchronisation, for code acquisition H04B1/7075, for code tracking H04B1/7085
• CPC Class Codes: H04J 13/00 Code division multiplex systems for frequency hopping H04B1/713
• CPC Class Codes: H04L 1/0001 Systems modifying transmission characteristics according to link quality, e.g. power backoff adaptive data allocation for multicarrier modulation H04L5/0044; controlling transmission power for radio systems H04W52/04
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/004 by using forward error control H04L1/0618 takes precedence; coding, decoding or code conversion, for error detection or correction H03M13/00
• CPC Class Codes: H04L 1/0042 Encoding specially adapted to other signal generation operation, e.g. in order to reduce transmit distortions, jitter, or to improve signal shape H04L1/0067 takes precedence
• CPC Class Codes: H04L 1/0047 Decoding adapted to other signal detection operation in conjunction with sequence estimation or equalization H04L25/03286
• CPC Class Codes: H04L 1/0056 Systems characterized by the type of code used H04L1/08 takes precedence
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 1/0083 : Formatting with frames or packets; Protocol or part of protocol for error control
• CPC Class Codes: H04W 36/0088 : Scheduling hand-off measurements
• CPC Class Codes: H04W 36/302 : due to low signal strength
• CPC Class Codes: H04W 52/08 : Closed loop power control
• CPC Class Codes: H04W 52/267 : taking into account the information rate
• CPC Class Codes: H04W 52/28 : using user profile, e.g. mobile speed, priority or network state, e.g. standby, idle or non transmission
• CPC Class Codes: H04W 52/287 : when the channel is in stand-by
• CPC Class Codes: H04W 52/288 : taking into account the usage mode, e.g. hands-free, data transmission, telephone
• CPC Class Codes: H04W 52/36 : with a discrete range or set of values, e.g. step size, ramping or offsets
• CPC Class Codes: H04W 52/362 : Aspects of the step size
• CPC Class Codes: H04W 52/367 : Power values between minimum and maximum limits, e.g. dynamic range
• CPC Class Codes: H04W 52/44 : in connection with interruption of transmission
• CPC Class Codes: H04W 52/48 : during retransmission after error or non-acknowledgment
• CPC Class Codes: H04W 52/56 : Detection of errors of TPC bits
• CPC Class Codes: H04W 52/60 : using different transmission rates for TPC commands
• CPC Class Codes: H04W 56/00 : Synchronisation arrangements

Abstract

In a compressed mode, a spread spectrum communication device interleaves bit units across multiple frames using an interleaver, reduces the spreading factor using a framing/spreading unit, outputs the compressed mode frames at a predetermined compressed mode frame timing, and increases the average transmission power in the compressed mode at a radio frequency transmitter. Furthermore, a handover between different frequencies is carried out by establishing synchronization to another frequency carrier, based on a first search code and a second search code which have been detected, and moreover, a handover between different communication systems is carried out by establishing synchronization to a GSM, based on an FCCH and a SCH which have been detected.

Claims

1. A spread spectrum communication device applied in a code division multiple access system for continuously transmitting frames in a normal mode, and intermittently transmitting compressed frames in a compressed mode, said device comprising:

a transmission section for using a desired spreading code to create transmission data of a quantity corresponding to a number of users who can be served thereby, in correspondence with the normal mode and the compressed mode, and adding and transmitting the transmission data created in correspondence with the number of users; and

a compressed mode control section, connected to said transmission section, for controlling the creation operation of transmission data by said transmission section in said compressed mode;

said compressed mode control section having

a frame combining unit for extracting from given combinations of multiple compressed mode frames, compressed by separate users in said transmission section, a combination having a total transmission duration of less than one frame duration;

a spreading code allocation unit for allocating the same spreading code to each of multiple channels which transmit the combination extracted by said frame combining unit; and

a transmission timing control unit for using a single spreading code, allocated by said spreading code allocation unit, to control said transmission section so that transmission timings of multiple compressed mode frames, which comprise the above extracted combination, do not temporally overlap within one frame duration.

2. A spread spectrum communication device applied in a code division multiple access system for continuously transmitting frames in a normal mode, and intermittently transmitting compressed frames in a compressed mode, said device comprising:

a compressing/intermittent receiving unit for intermittently receiving a compressed frame in the compressed mode;

a search code detecting and determining unit for detecting in other frequency carriers, during non-transmission period in the compressed mode, a first search code, which is shared at all base stations and is time-continually transmitted, and a second search code, which is transmitted at the same time as the first search code and can be identified by multiple numeric patterns, and determining these search codes based on a predetermined reference; and

a control unit for selecting said compressing/intermittent receiving unit during intermittent receiving, selecting said search code detecting and determining unit during non-transmission period, and controlling operations of both;

wherein

said control unit establishes synchronization to the other frequency carrier, based on the first search code and second search code detected by said search code detecting and determining unit, and thereby controlling a handover between different frequencies.

3. The spread spectrum communication device according to claim 2 wherein said control unit

carries out control to detect at least one first search code during not more than half of one frame in the non-transmission period,

thereafter, carries out control to repeat the processing of shifting the non-transmission period by a predetermined slot unit, and to detect a numeric value of all second search codes using multiple frames, and

establish synchronization to the other frequency carrier, based on the numeric pattern of the detected first search code and second search code, thereby controlling a handover between different frequencies.

4. The spread spectrum communication device according to claim 3, wherein the non-transmission duration can be arranged across multiple frames.

5. The spread spectrum communication device according to claim 4, characterized in that, when no search code can be obtained which satisfies a predetermined level of reliability during the search code detection, a search code is detected again in the place.

6. A spread spectrum communication device applied in a code division multiple access system for continuously transmitting frames in a normal mode, and intermittently transmitting compressed frames in a compressed mode, said device comprising:

a compressing/intermittent receiving unit for intermittently receiving a compressed frame in the compressed mode;

an information detecting and determining unit for detecting in another communication system, during non-transmission period in the compressed mode, a first information for tuning frequencies, and a second information for achieving synchronization, and determining the first and second information based on a predetermined reference; and

a control unit for selecting said compressing/intermittent receiving unit during intermittent receiving, selecting said information detecting and determining unit during non-transmission period, and controlling operations of both;

wherein

said control unit establishes synchronization to the other communication system, based on the first information and second information detected by said information detecting and determining unit, and thereby controlling a handover between different frequencies.

7. The spread spectrum communication device according to claim 6, wherein said control unit

carries out control to detect at least one first information during the non-transmission period which is not more than half of one frame,

thereafter, carries out control to set the non-transmission period based on a time predetermined by the detected first information, and to detect the second information,

and establishes synchronization to said other communication system, based on the detected first information and second information, thereby controlling a handover between different frequencies.

8. A spread spectrum communication method applied in a code division multiple access system for continuously transmitting frames in a normal mode, and intermittently transmitting compressed frames in a compressed mode, said method comprising:

a first step of compressing frames, which are units of a transmission data stream, in multiple transmission channels performing compressed mode transmission;

a second step of extracting from given combinations of multiple compressed mode frames, compressed separately for users in said first step, a combination having a total transmission duration of less than one frame duration;

a third step of allocating the same spreading code to each of multiple channels for transmitting multiple compressed mode frames which comprise the combination extracted in said second step; and

a fourth step of using a single spreading code, allocated in said third step, to transmit multiple compressed mode frames, which comprise the combination extracted in said third step, so that their transmission timings do not temporally overlap within one frame duration.

9. A spread spectrum communication method applied in a code division multiple access system for continuously transmitting frames in a normal mode, and intermittently transmitting compressed frames in a compressed mode, said method comprising:

a first search code detecting step of detecting at least one first search code in not more than half of one frame during the non-transmission period; and

a second search code detecting step of thereafter repeating the processing of shifting the non-transmission period in units of predetermined slots, and detecting a numeric value of all second search codes using multiple frames;

wherein

a handover between different frequencies is controlled by establishing synchronization to another frequency carrier, based on the numeric pattern of the detected first search code and second search code.

10. The spread spectrum communication method according to claim 9, wherein the non-transmission period can be arranged across multiple frames.

11. The spread spectrum communication method according to claim 10, characterized in that, when no search code can be obtained which satisfies a predetermined level of reliability during said search code detection, a search code is detected again in the place.

12. A spread spectrum communication method applied in a code division multiple access system for continuously transmitting frames in a normal mode, and intermittently transmitting compressed frames in a compressed mode, said method comprising:

a first information detecting step of detecting a first information for tuning frequencies in not more than half of one frame during the non-transmission period; and

a second information detecting step of detecting second information for setting the non-transmission period, based on the timing determined beforehand from said detected first information, and achieving synchronization;

wherein

a handover between different frequencies is controlled by establishing synchronization to another communication system, based on the detected first information and second information.

13. A spread spectrum communication device applied in a code division multiple access system for continuously transmitting multiple frames, a frame being a unit of transmission data, in a normal mode and intermittently transmitting compressed frames in a compressed mode, said device comprising:

a compressing/intermittent transmitting unit configured to compress a frame into a compressed frame, which comprises multiple slots and is a unit of a transmission data stream, and to transmit intermittently the compressed frame;

a control unit configured to control said compressing/intermittent transmitting unit so as to slot the compressed frame into a slotted frame, and to transmit intermittently the slotted frame in N (a natural number) slot units, wherein

said control unit is configured to determine the N slot units in accordance with a relationship between a measuring period of other frequency carrier components and an amount of transmission power control error.

14. The spread spectrum communication device according to claim 13, further comprising:

an interleaving unit configured to interleave in bit units a frame or a compressed frame so as to reduce an effect of transmission errors; and

said control unit configured to control said interleaving unit so that, in the compressed mode, interleaving in bit units is performed across multiple frames.

15. A spread spectrum communication device applied in a code division multiple access system for continuously transmitting frames in a normal mode and intermittently transmitting interleaved and compressed frames in a compressed mode, comprising:

an interleaving unit configured to interleave in bit units at least one of an uncompressed frame and a compressed frame;

a compressing unit coupled to at least one of an output and an input of the interleaving unit and configured to compress an interleaved frame or a non-interleaved frame, respectively;

a transmitting unit coupled to at least one of the interleaving unit and the compressing unit and configured to transmit an interleaved and compressed frame to another device; and

a control unit coupled to each of said interleaving unit, said compressing unit, and said transmitting unit and configured to control said interleaving unit, said compressing unit, and said transmitting unit, wherein

said compressing/intermittent transmitting unit comprises a memory having a memory size in correspondence with a number of frames to be code-multiplexed in said compressed mode.

16. The spread spectrum communication device according to claim 15, comprising:

said control unit configured to control said interleaving unit so that, in the compressed mode interleaving in bit units is performed across multiple frames.