• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    According to the present invention there is provided an apparatus and method for iteratively decoding a signal. The decoding apparatus of the present invention includes a central pool composed of resources for repeatedly decoding a signal. The central pool may perform multiple iterative decoding processes, with each decoding process assigned to a signal processing unit according to the validity of the request and the resource.
    公开号:KR19990068162A
    申请号:KR1019990002544
    申请日:1999-01-27
    公开日:1999-08-25
    发明作者:루시카를로；뮤타바사이어드아온；산델매그너스；스트라흐파울에드워드；브린크스테판텐；얀란-홍
    申请人:루센트 테크놀러지스 인크；
    IPC主号:
    专利说明:

    Iterative decoding on demand
    The present invention relates to iterative decoding of a signal at a base station of a multiuser detection and demodulation system (hereinafter referred to as MDDS), eg a digital wireless communication system.
    Recently, advances in the communication theory (which employs the "Turbo Principle") have applied repeated decoding steps to received data in some digital communication systems, including wireless communication in which a plurality of users communicate to one receiver. We have shown that we can improve the quality of decoded signals. In particular, a paper published by Bauch Khorram and hagenauer, "Iteractive Equalization iteractive decoding in Mobile Communcation System" (Germany, Bonn, October 1997, pages 307-312 of EPMCC'97), transmits encoded data transmitted over a mobile radio channel. It describes the application of the turbo principle to iterative decoding. In order to be suitable for iterative decoding, the transmitted signals need to be encoded by at least two concatenated codes, which are concatenated in series or in parallel.
    The signal is then decoded in a first decoding step to provide a soft output based on the reliability of the hard decision value, where the first decoder decodes the inner code and the second decoder the outer code. It is used to decode it. In the first iteration, the decoding step is repeated and the soft output value is used as the input value for the first and second decoders.
    In a particular application of a mobile communication system, a channel encoder and an intersymbol interference (ISI) -channel may be seen as a serially coupled encoding method, where the channel encoder functions as an external encoder and the ISI channel is an internal block encoder (rate). It functions as 1). As such, iterative decoding is particularly suitable for the application to the European wireless digital cellular standard "GSM" in which the equalizer performs the internal decoding step and the decoder performs the external decoding step. In case of poor communication channel conditions (low SNR, fading, multipath propagation, etc.), the BER is improved by each iterative decoding step until the bit error rate (hereinafter referred to as BER) low is reached. Can be. The signal received by the base station is equalized to provide a soft decision value of the received coded bits.
    Repeating the decoding step a few times can improve the BER of the received signal. However, each iterative decoding step consumes resources such as memory, computation time, and tie-up dedicated ASICs (custom integrated circuits). At a particular base station, the number of signals that can be decoded in parallel is limited by the number of valid signal processing units (SPUs). That is, iterative decoding hardware such as a digital signal processor (hereinafter referred to as DSP), and software are provided to each CPU, thereby increasing the cost and complexity of the base station.
    1 is a schematic diagram of a mobile station suitable for MDDS in accordance with the present invention;
    2 is a schematic diagram of a base station according to the prior art;
    3 is a schematic diagram of a multiuser mobile wireless communications system according to the prior art;
    4 is a detailed view of a multiuser signal processing device according to the present invention.
    5 shows the transmission of signals by air interface.
    6 is a diagram illustrating another example of signal transmission by an air interface.
    Explanation of symbols on the main parts of the drawings
    11: Analog to Digital Converter (A / D) 12: Encoder / Modulator
    13: digital-to-analog converter (D / A) 15: transmitter
    According to the first aspect of the present invention,
    A signal processing unit; And
    10. An apparatus for repeatedly decoding a signal, comprising repeating decoding resources for performing at least one iterative decoding process on the signal.
    The iterative decoding resource is located in a central pool and is assigned to the signal processing unit when iterative decoding processing is required.
    Each user of an MDDS may have a different Quality of Service (QoS) condition. That is, due to the difference in communication services, it may have different BER and latency limitations. For example, in the case of voice communication, as a condition, the BER must be the lowest (i.e., many bit errors can be tolerated), and the latency must be strongly limited (i.e. long latency is not allowed in two-way conversations). . In the case of visual communication, the BER should be maximum and the latency should be strongly limited. In the case of data communication (eg, wireless Internet web-browsing), the BER should be maximum but the limitation of latency should be relaxed. When each user communicates with a base station, different signal properties (i.e., SNR), multipath propagation, and fading occur due to different distances from the base station, radio environment, and speed in the case of mobile communication.
    An advantage of the present invention is that each user can vary the number of repetitive decoding steps so that targeted QoS conditions can be achieved.
    The invention is described below by way of example with reference to a mobile cellular communication system and figures.
    An end-user device, such as a mobile station, may use any of a number of communication protocols to communicate with a nearby base station using a plurality of communication channels via an air interface. 1 schematically illustrates a mobile station, where voice information is received by microphone 10 and converted into a digital data stream by analog-to-digital (A / D) converter 11. The converted data stream is then properly coded and modulated in the encoder / modulator 12, in accordance with the communication protocol required by the mobile cellular communication system. This encoded data stream is then converted into an analog signal in a digital-to-analog converter (D / A) 13 and high-converted in the up-converter 14 to the appropriate radio frequency. This data signal is amplified by the transmitter 15 and transmitted by the antenna 16 to the local base station through the communication channel of the air interface. If the mobile station needs to transmit a signal other than voice (e.g., e-mail, fax, etc.), these data are supplied directly to the encoder / demodulator 12 via the data transmission line 17 in digital format. do.
    The transmitted signal can be received by the base station and demodulated and decoded, as shown in FIG. Receive antenna 20 and receiver 21 provide a power amplified analog signal, which, in down converter 22, is demodulated down to a frequency suitable for further processing. This converted signal is then digitized by the A / D converter 23, demodulated by the demodulator 24, and repeatedly decoded by the equalizer 26 and the decoder 27 along the repetition path 25. An improved signal is to be provided. The A / D converter 23, demodulator 24, equalizer 26, and decoder 27 together form a signal processing unit 28 for digital baseband processing of the received signal. In GSM (European Wireless Digital Cellular Standard), data is transmitted in bursts of 150 bits, with each burst being repeatedly decoded. If any other communication protocol is employed, the data will be processed into blocks or packets for repetitive decode processing. The improved signal is then forwarded to the controller 29 of the base station which determines if this signal is suitable for connection to a public switched telephone network or other mobile switching center, for example. This base station controller is connected to a transmitter apparatus (not shown) of the base station which transmits information and other control signals back to the mobile station.
    3 illustrates a multiuser system according to the prior art. The multi-user system includes a plurality of mobile stations (1, 2, ..., k), each of which has different QoS conditions and channel conditions. The multiuser system includes a plurality of signal processing units (hereinafter referred to as SPUs) 28a, 28b,... 28k and SPU selector 23 integrated into signal processing units 30 for multiple users. It also includes a base station. The plurality of mobile stations that can be connected to the base station and communicate via the base station is limited by the number of valid SPUs. Each SPU requires a complex digital signal processor in the iterative decode processing path 25, and each DSP is redundant in each SPU, making the base station expensive.
    4 shows a multiuser signal processing device 30 according to the present invention. The signal processing device comprises a selector 32, a plurality of repetitive signal processing units (hereinafter referred to as ISPUs) 40a, 40b, ..., 40k, and hardware effective for repetitive decode processing of signals received at the base station; It includes a pool 41 composed of software resources. This pool contains a plurality of DSPs, memory, and algorithms for iterative decode processing included in dedicated software. Each ISPU requests resources in the pool via a schedule control unit (hereinafter referred to as SCU) 42a, 42b, ..., 42k. After the signal is received, amplified and low-converted by the antenna 20, the receiver 21, and the down converter 22 (not shown in FIG. 4), it is assigned to the ISPU by the selector 32. . The ISPU digitizes this signal using A / D converters 23a, 23b, ..., 25k and demodulates it with demodulators 24a, 24b, ..., 24k. Simple decoders 43a, 43b, ..., 43k provide basic bit estimates to the SCU. In the estimators 44a, 44b, ..., 44k, the bit error rates (BER) are estimated, and the extractors 45a, 45b, ..., 45k are informed from the signals relating to QoS conditions and call priorities from these signals. Extract This information is fed back to the SCU so that the appropriate resources in the pool can be requested. The BER estimation and information extraction are performed sequentially, allowing the SCU to dynamically change the requested resource according to varying signal processing conditions. When the BER and QoS reach an acceptable level, as described above, the signal is passed from the ISPU to the base station controller 29.
    Resources allocated to a particular ISPU may be updated dynamically, continuously, or step by step (eg, every 5 seconds) during a call. During the call, the number of repetitions required to obtain the targeted signal quality may vary, for example, depending on the signal propagation environment. Similarly, during a call, the amount of communication can increase, so that the QoS conditions of the mobile station can change. For example, a mobile station that exchanges data for updating its e-mail may have different QoS conditions when downloading data and when uploading data.
    In FIG. 4, each SCU starts a partial recognition, ie, iterative decoding processing with QoS restrictions and resources currently available in the pool. Thereby, resources are allocated in the manner that first come first seved. The pool should remove resources from specific SCUs and require a central resource allocation controller if needed. This central SCU controller can be used to recognize high priority calls, such as calls for emergency services, and to arrange resources appropriately.
    Alternatively, the SCUs may be interconnected. According to this, each SCU will begin iterative decoding with a global knowlede. Thus, in order to optimize the utilization of available resources, the SCU will be able to change resources and negotiate pools. This example is particularly advantageous for systems where the pool is usually fully loaded and many arcs have the same priority. A central SCU controller is not required but without it the implementation of each SCU becomes more complicated.
    A typical call can be initiated by either the mobile station or the base station. In any case, call setup is done on a different channel than the main communication channel, which allows data exchange between the base station and the mobile station. The kth mobile station establishing the call is assigned to the kth ISPU of the multiuser signal processing device 30 by the selector 32. Between call setups, the SCU 42k uses a simple decoder, bit error rate estimator 44k, and information extractor 45k to determine the initial QoS conditions for the call and the priority of the call. In accordance with these parameters, the SCU requests DSP and memory resources in the pool via data connection 46. Each "block" of incoming data is delivered to the pool by data line 46. The iterative decoding process is repeated several times in the pool until the required bit error rate is reached, or until the maximum latency is about to be exceeded. This signal is then sent back to the SCU via the data transmission line 47 and sent to the base station controller 29. In the case where the latency is very tightly limited, the SCU may require several DSPs and memory groups in order for several iterative decoding processes to be performed in parallel. During the call, the SCU dynamically controls the allocated resources using a simple decoder, BER estimator, and information extractor. For example, if the signal quality is improved, only a few iterative or iterative processes will be needed to match the BER target within certain latency limits. In contrast, poor signal quality will require many iterative processes to provide a data signal that matches the BER target within certain latency limits. When the call is terminated and the allocated resources are pooled, it is effective that the next call received at the base station, or a low priority established call already waiting for many resources, becomes free.
    5 illustrates the transmission of a digital signal from a mobile station to a base station by air interface, where the communication channel functions as an internal encoder. Figure 6 illustrates the transmission of digital signals via a communication channel and also via an air interface, where two encoders (internal encoder and external encoder) are used, and various iterative decoding paths are shown.
    While the present invention has been described by way of examples, other examples will be apparent to those skilled in the art without departing from the scope of the present invention. For example, the function of the SCU may be performed by a central resource, and the BER estimator and extraction function may be performed in the central pool. The system may use any one of a number of communication protocols without departing from the spirit of the invention.
    The present invention arranges decoding resources in a central pool, and assigns them to the signal processing unit when iterative decoding processing is required, thereby allowing each user to repeatedly decode so that a targeted QoS condition can be achieved. The number of steps can vary.
    权利要求:
    Claims (8)
    [1" claim-type="Currently amended] A signal processing unit,
    An apparatus for repeatedly decoding a signal, comprising: a repetitive decoding resource for performing at least one repetitive decoding process on the signal.
    The iterative decoding resource is placed in a central pool and is allocated to the signal processing unit when iterative decoding processing is required.
    [2" claim-type="Currently amended] The decoding apparatus of claim 1, wherein the decoding apparatus includes a plurality of signal processing units, and each signal processing unit is accessible to the central pool.
    [3" claim-type="Currently amended] 2. The decoding apparatus according to claim 1, wherein each signal processing unit includes a control unit that requests the iterative decoding resource in the central pool.
    [4" claim-type="Currently amended] 4. The decoding apparatus according to claim 3, wherein each signal processing unit is allocated the iterative decoding resource from the central pool in accordance with a request from each control unit.
    [5" claim-type="Currently amended] 5. The decoding apparatus of claim 4, wherein the iterative decoding resource allocated to the signal processing unit is changed during decoding.
    [6" claim-type="Currently amended] Receiving a signal for decoding;
    10. A method for iteratively decoding a signal, comprising performing at least one iteration decoding process on the signal using an iterative decoding resource.
    And when iterative decoding processing is required, the iterative decoding resource is requested and allocated from a central pool.
    [7" claim-type="Currently amended] 7. The decoding method according to claim 6, wherein a plurality of signals are received for decoding.
    [8" claim-type="Currently amended] 8. The method of claim 7, wherein the allocated iterative decoding resource can be changed when the signal is decoded.
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    同族专利:
    公开号 | 公开日
    JPH11313037A|1999-11-09|
    US6271772B1|2001-08-07|
    BR9900021A|2000-01-04|
    EP0932259A1|1999-07-28|
    CN1237045A|1999-12-01|
    ID21813A|1999-07-29|
    AU1321399A|1999-09-30|
    JP3195587B2|2001-08-06|
    CA2254644C|2002-08-06|
    KR100348036B1|2002-08-09|
    CA2254644A1|1999-07-27|
    AU722426B2|2000-08-03|
    TW437176B|2001-05-28|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    1998-01-27|Priority to EP98300556.2
    1998-01-27|Priority to EP19980300556
    1999-01-27|Application filed by 루센트 테크놀러지스 인크
    1999-08-25|Publication of KR19990068162A
    2002-08-09|Application granted
    2002-08-09|Publication of KR100348036B1
    优先权:
    申请号 | 申请日 | 专利标题
    EP98300556.2|1998-01-27|
    EP19980300556|EP0932259A1|1998-01-27|1998-01-27|Iterative decoding on demand|
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