CN101107781B - Enhanced performance coding and error correction system and method for legacy communication networks - Google Patents

Abstract

An encoding and error correction system and method employs an AMR codec (18) by stripping header data from a plurality of legacy system frames (10) having header and traffic channel (TCH) data blocks.Speech data is then encoded using the AMR to create bits for a data block substantially the same as contained in the plurality of frames. The stripped header data is encoded as a long frame header using a fixed convolution coder(24). The speech data is then convolutionally encoded and the long frame header and encoded speech data are combined as a long frame (32). The long frame is then deconstructed into a plurality of equal segments (106, 110) and the segments are transmitted as TCH data in the legacy system frame format.

Description

Enhanced performance coding and error correction system and method for legacy communication networks

technical field

The present invention relates generally to the field of coding and error correction for transmission systems, and more particularly to the use of advanced vocoders (vocoders) with bit mapping and coding to improve legacy communication systems for enhanced correction wrong performance.

Background technique

Waveform source coding and decoding (codec) is widely used in early digital mobile communication systems, such as Personal Handyphone System (PHS). Due to technical limitations at the time of implementation, some system designs do not provide proper channel coding/decoding to protect the transmitted data. For these systems, speech performance is unacceptable and some important control bits are easily corrupted in order to ensure a high bit error rate when channel quality conditions deteriorate. As a result, upper layer protocols and control mechanisms in the system may be activated to shut down the channel. This is one of the most common reasons for loss of connection during an ongoing communication session.

In some advanced 2G mobile systems and all 3G systems there is an Adaptive Multi-Rate (AMR) vocoder and corresponding channel coding capability. Under the AMR standard, there are 8 different data rates for the Code Excited Linear Prediction (CELP) speech codec. These data rates range from 12.2kbps to 4.75kbps. The more voice information that is transmitted, the better the sound performance achieved. The basic approach taken in the AMR standard is this: when channel conditions get worse, the system uses a mode with a lower data rate (and, of course, poorer sound performance). This saves more channel bandwidth and other resources of the system to improve bit error correction capability. The lack of comparable technology in legacy digital mobile systems (eg PHS) stems from the expense of algorithms being developed and integrated circuit resources related to power and instruction speed requirements. With the advent of silicon technology, the use of digital signal processors (DSP) in PHS mobile phones is no longer a luxury element.

Therefore, it is desirable to be able to use AMR vocoder capabilities in legacy systems.

It is also desirable to be able to apply AMR and error correction in a way that could improve early 2G systems by rearranging the bitmap to provide up to a 6 to 7dB gain to the bit error reduction capability of certain AMR modes.

Contents of the invention

The encoding and error correction system and method according to the present invention take advantage of the modern benefits of the AMR codec by stripping header data from multiple legacy system frames with header and traffic channel (TCH) data blocks. The speech data is then encoded using AMR to create bits for substantially identical blocks of data contained in multiple frames. The stripped header data is encoded as a long frame header using a fixed convolutional encoder. The speech data is then convolutionally encoded, and the longframe header and encoded speech data are combined into a longframe. The long frame is then deconstructed into multiple equal segments, and these segments are sent as TCH data in the legacy system frame format.

The coding and error correction method according to the embodiment of the present invention comprises the following steps: stripping header data from a plurality of legacy system frames having headers and traffic channel (TCH) data blocks; collecting substantially the same period as a plurality of time slots Speech data in the period of time; Coding the stripped header data into a long frame header; Encoding the speech data; Combining the long frame header and encoded speech data into a long frame; Decoding the long frame forming a plurality of equal segments; and transmitting the segments as TCH data in the legacy system frame format.

Wherein, the encoding of the voice data includes using an AMR codec. The stripped header data includes channel identifiers and slow-related control channel data. The encoding of the stripped header data includes using a fixed convolutional code The AMR codec has multiple modes and the method also includes the step of selecting a codec mode based on channel quality. The convolutional encoder is a 1/2 convolutional encoder. The selected mode Steps include moving patterns down within a class when BER deteriorates, across classes at the lowest class limit, up within a class when BER improves, and across classes at the highest class limit.

An encoding and error correction system according to an embodiment of the invention, comprising: means for stripping header data from a plurality of legacy system frames having header and traffic channel (TCH) data blocks (12a, 12b, 12c, 12d) (20); The device (18) that is used to collect the voice data in the time period that is substantially the same as the period of a plurality of time slots; The device (20) that is used to encode the header data that strips out is a long frame head; means (24) for encoding said speech data; means for combining said long frame header and encoded speech data into a long frame (32); for decomposing said long frame into a plurality of equal subdivisions means for segmenting (34a, 34b, 34c, 34d); and means for transmitting said segment as TCH data in said legacy system frame format.

Wherein, the encoding of the voice data comprises using an AMR codec (18), which has a plurality of modes, and the system further comprises means for selecting a codec mode based on channel quality. In said means for selecting a codec mode, means for moving modes down (72, 74, 76) within a class when BER deteriorates, and across classes (78) at the lowest class limit means, and means for moving up (80, 82, 84) within a class when BER improves, and across classes (86) at the highest class limit.

Description of drawings

These and other features and advantages of the present invention will be better understood by referring to the following detailed description when taken in conjunction with the accompanying drawings in which:

Fig. 1 is the block diagram of prior art PHS system traffic channel frame and time slot structure;

Figure 2 is a block diagram of the bit mapping and encoding used to construct long frames to deconstruct standard PHS slots for transmission;

Fig. 3 is a block diagram of a long frame after bit mapping;

Fig. 4 is the block diagram that is used for the robust (Robust) AMR traffic synchronization control channel (RATSCCH) format of long frame;

Figure 5 is a block diagram of an interleaving scheme for coded data;

Fig. 6 is a schematic diagram of elements of a mobile phone and a base station system using the present invention;

Fig. 7 a is the table that is used for the AMR mode of the present invention and the division of mode (Mode) and category (class); And

Fig. 7b is a flow chart of the mode switching algorithm using categories adopted by the present invention.

Detailed ways

The present invention is defined for an exemplary embodiment employing the PHS communication system and standard (2G legacy mobile system). A PHS system incorporating the technology of the present invention will be referred to herein as an advanced PHS (APHS).

The data mapping of the traffic channel (TCH) of an exemplary PHS system is shown in Figure 1. PHS is a time division multiplexing (TDMA) system. A frame 10 is 5 ms in length and is divided into 8 time slots, of which 4 time slots 4 slots are used for uplink and 4 slots are used for downlink. In each direction, three slots T1, T2 and T3 can be used for three different users, while the last slot is used for Common control channel for all three users, which alternates between uplink mode commands and downlink mode commands C_up and C-down.

In FIG. 1 , time slot T2 is expanded here as an example time slot 12 and discussed in detail to illustrate the invention. Areas PR and UW are used for synchronization of the physical layer. Block UW incorporates 16 bits. As will be discussed in more detail later, PR and UW are inserted into the transmitted frame prior to the decoder so that they cannot be encoded. CI and SA are protocols for slot format information and connection status, which are very important for connection reliability. Block CI contains 4 bits and block SA contains 16 bits. TCH contains voice data and consists of 160 bits. A 16-bit CRC block provides error detection bits. It can be seen that within one frame, there are 160 bits of speech data, so the total vocoder rate is 160/0.05=32Kbps. This is the data rate of ADPCM (ITU G.726) adopted by PHS.

The present invention adopts AMR codec combined with bit mapping to construct frames compatible with PHS sending standards, and adds coding to enhance performance. There are 8 vocoder modes in the AMR system. These 8 modes are defined by GSM and 3GPP international standards, and the adopted data rates are 12.2, 10.2, 7.95, 7.4, 6.7, 5.9, 5.15 and 4.75 (Kbps). Each of these rates is below the 32Kbps basic capability of the PHS system and allows for flexible formatting of the data to be encoded.

As will be described in more detail later, the source speech and channel coding provided by the present invention is completed within 20 ms (or 4 PHS slot times). The interleaving of 20ms blocks is below the human ear sensitivity threshold. The newly encoded "frames" are referred to herein as long frames. In order to be compatible with the bitmap of the PHS standard frame, the present invention does not utilize CI, SA and CRC areas. That is, coded CI and SA data are put into TCH blocks. Vocoder pattern related messages are coded with specific channel code patterns and employ specific regions and coders. The larger the size of the channel coded data block, the better the result (higher bit error tolerance). Finally, a new control channel for long frame synchronization, the Robust AMR Traffic Synchronization Control Channel (RATSCCH), is adopted at the very beginning of the connection between the handset and the base station. In some special cases, RATSCCH is also used for mode messages.

TCH blocks are used for voice data, SA/CI and in-band data. Different vocoder modes have different speech and channel coding parameters and require different data transmission rates. SA/CI and in-band information are coded and require a constant data rate. Coding and bit mapping in APHS are shown in Figure 2.

The four PHS slots 12a, 12b, 12c and 12d nominally provide long frames. The CI and SA data of these four slots are stripped and combined into the APHS long frame header block 14 . Nominally, 20 ms speech samples 16 are processed through an AMR vocoder 18 . Long frame header data is processed through a first encoder 20 and in-band data 22 is inserted, followed by AMR processed speech samples which are routed through a second encoder 24 which is convolutional. The resulting long frame is shown in Figure 3, where the header 26 contains 156 bits of CI and SA data, an in-band block 28 carries 8 bits, followed by a 476-bit coded speech data block 30, resulting in a 640-bit long frame 32. As mentioned above, this long frame is then segmented into four 160-bit lengths for insertion into the standard TCH blocks of the four APHS frames 34a, 34b, 34c and 34d for transmission.

In the PHS system, the data rate resource in the regional TCH for the long frame is TCH*4=160*4=640 bits. For compatibility, the raw area containing SA/CI data in each slot is reserved in APHS, but for processing in APHS, these data are ignored. The message SA/CI is encoded together with the in-band message data and placed in the original TCH area.

In the described APHS embodiment, the maximum encoded speech data in a long frame is 476 bits. Different vocoder modes and channel coding modes with different parameters are combined to generate different encoded speech data blocks with different sizes. If the generated coded speech data block is larger than 476 bits, some bits have to be truncated. In the APHS embodiments disclosed herein, channel coding is implemented using a convolutional coder. In alternative embodiments, other channel coding methods are employed.

It will be discussed later that based on data interleaving, CI data only needs to be sent once in each long frame (equivalent to sending one every 4 PHS frames). SA data needs to be sent every time slot. For SA/CI, the The generated long frame data is shown in Table 1.

Table 1

name SA0 SA1 SA2 SA3 number of bits 16 16 16 16

name CI number of bits 4 Number of CRC bits 6 polynomial D⁶+D⁵+D³+D²+D<sup>1</sup >+1 The number of input bits for the convolutional encoder 74 Polynomials for 1/2 convolutional encoders Polynomial G0/G0＝1G1/G0＝1+D+D³+D⁴/1+D³+D⁴ with trailing 8 bits Number of output bits 148+8=156

8 bits are used for mode information, which is mapped to the last 8 bits of the long frame, which will be shown below.

Table 2 shows the codec modes and associated convolution rates, the number of bits input to the convolutional encoder, the number of output bits produced from the encoder, the number of CRC and SA bits after the 1/2 convolutional encoder, Total number of bits and preferred class.

Table 2

codec mode Ratio The number of bits input to the convolutional encoder The number of bits output from the convolutional encoder (should be 476) Number of SA bits after CRC and 1/2 convolutional encoder Total number of bits for a block of 20ms (total 632+8=640) preferred category TCH/AFS12.2 1/2 250 508 truncated 32 bits 156 632 1 TCH/AFS10.2 1/3 210 642 truncated to 166 bits 156 632 2 TCH/AFS 1/3 165 513 156 632 1 7.95 truncated 37 bits TCH/AFS7.4 1/3 154 474 156 630 2 TCH/AFS6.7 1/4 140 576 truncated 100 bits 156 632 1 TCH/AFS5.9 1/4 124 520 truncated 44 bits 156 632 2 TCH/AFS5.15 1/5 109 565 truncated 89 bits 156 632 1 TCH/AFS4.75 1/5 101 535 truncated 59 bits 156 632 2

As shown in the table, the fixed number of bits for SA/CI data is 156, and for four frames, a total of 640 bits are available to fill in the 160-bit PHS TCH, and the bits from the speech data convolutional encoder should total 476 bits , and the bits must be truncated to fit the long frame.

Exemplary convolutional encodings for each codec mode are shown in Table 3-10, where truncated bits are defined to keep the long frame size at 640 bits.

table 3

TCH/AFS 12.2 codec:

A block of 250 bits {u(0)...u(249)} is encoded using a 1/2 rate convolutional coding defined by the following polynomial:

G0/G0=1

G1/G0＝1+D+D ³ +D ⁴ /1+D ³ +D ⁴

yields 508 coded bits {C(0)...C(507)}, defined by:

r(k)=u(k)+r(k-3)+r(k-4)

C(2k)=u(k)

C(2k+1)=r(k)+r(k-1)+r(k-3)+r(k-4) for k=0,1,...,249;

r(k)=0 for k<0

and (for the encoder's termination):

(k)=0

C(2k)=r(k-3)+r(k-4)

C(2k+1)=r(k)+r(k-1)+r(k-3)+r(k-4) for k=250,251,...,253

The code is truncated in such a way that the following 32 bits are not sent: C(417), C(421), C(425), C(427), C(429), C(433), C( 437), C(441), C(443), C(445), C(449), C(453), C(457), C(459), C(461), C(465), C( 469), C(473), C(475), C(477), C(481), C(485), C(489), C(491), C(493), C(495), C( 497), C(499), C(501), C(503), C(505) and C(507).

Table 4

TCH/AFS 10.2 codec:

A block of 210 bits {u(0)...u(209)} is encoded using a 1/3 rate convolutional coding defined by the following polynomial:

G1/G3＝1+D+D ³ +D ⁴ /1+D+D ² +D ³ +D ⁴

G2/G3＝1+D ² +D ⁴ /1+D+D ² +D ³ +D ⁴

G3/G3=1

This results in 642 coded bits {C(0)...C(641)}, defined by:

r(k)=0

C(3k)=r(k)+r(k-1)+r(k-3)+r(k-4)

C(3k+1)=r(k)+r(k-2)+r(k-4)

C(3k+2)=r(k-1)+r(k-2)+r(k-3)+r(k-4) for k=210,211,...,213

The codes are truncated in such a way that the following 22 bits are not sent: C(1), C(4), C(7), C(10), C(16), C(19), C( 22), C(28), C(31), C(34), C(40), C(43), C(46), C(52), C(55), C(58), C( 64), C(67), C(70), C(76), C(79) and C(82). All these operations will result in 620 bits.

The codes are truncated in such a way that the following 166 bits are not sent: C(1), C(4), C(7), C(10), C(16), C(19), C( 22), C(28), C(31), C(34), C(40), C(43), C(46), C(52), C(55), C(58), C( 64), C(67), C(70), C(76), C(79), C(82), C(88), C(91), C(94), C(100), C( 103), C(106), C(112), C(115), C(118), C(124), C(127), C(130), C(136), C(139), C( 142), C(148), C(208), C(211), C(214), C(220), C(223), C(226), C(232), C(235), C( 238), C(244), C(247), C(250), C(256), C(259), C(151), C(154), C(160), C(163), C( 166), C(172), C(175), C(178), C(184), C(187), C(190), C(196), C(199), C(202), C( 262), C(268), C(271), C(274), C(280), C(283), C(286), C(292), C(295), C(298), C( 304), C(307), C(310), C(316), C(319), C(322), C(325), C(328), C(331), C(334), C( 337), C(340), C(343), C(346), C(349), C(352), C(355), C(358), C(361), C(364), C( 367), C(370), C(373), C(376), C(379), C(382), C(385), C(388), C(391), C(394), C( 397), C(400), C(403), C(406), C(409), C(412), C(415), C(418), C(421), C(424), C( 427), C(430), C(433), C(436), C(439), C(442), C(445), C(448), C(451), C(454), C( 457), C(460), C(463), C(466), C(469), C(472), C(475), C(478), C(481), C(484), C( 487), C(490), C(493), C(496), C(499), C(502), C(505), C(508), C(511), C(514), C(517), C(520), C(523), C(526), C(529), C(532), C(535), C(538), C(541), C(544), C(547), C(550), C(553) and C(556).

table 5

TCH/AFS 7.95 codec:

A block of 165 bits {u(0)...u(164)} is encoded using a 1/3 rate convolutional coding defined by the following polynomial:

G4/G4=1

G5/G4＝1+D+D ⁴ +D ⁶ /1+D ² +D ³ +D ⁵ +D ⁶

G6/G4＝1+D+D ² +D ³ +D ⁴ +D ⁶ /1+D ² +D ³ +D ⁵ +D ⁶

This results in 513 coded bits {C(0)...C(512)}, defined by:

r(k)=u(k)+r(k-2)+r(k-3)+r(k-5)+r(k-6)

C(3k)=u(k)

C(3k+1)=r(k)+r(k-1)+r(k-4)+r(k-6)

C(3k+2)=r(k)+r(k-1)+r(k-2)+r(k-3)+r(k-4)+r(k-6)

For k=0,1,...,164

r(k)=0 for k<0

and (for the encoder's termination):

r(k)=0

C(3k)=r(k-2)+r(k-3)+r(k-5)+r(k-6)

C(3k+1)=r(k)+r(k-1)+r(k-4)+r(k-6)

C(3k+2)＝r(k)+r(k-1)+r(k-2)+r(k-3)+r(k-4)+r(k-6) for k=165 ,166,...,170

The codes are truncated in such a way that the following 37 bits are not transmitted: C(1), C(2), C(4), C(5), C(8), C(22), C( 70), C(118), C(166), C(214), C(262), C(310), C(317), C(319), C(325), C(332), C( 334), C(341), C(343), C(349), C(356), C(358), C(365), C(367), C(373), C(380), C( 382), C(385), C(389), C(391), C(397), C(404), C(406), C(409), C(413), C(415), and C (512).

Table 6

TCH/AFS 7.4 codec:

A block of 154 bits {u(0)...u(153)} is encoded using a 1/3 rate convolutional coding defined by the following polynomial:

G1/G3＝1+D+D ³ +D ⁴ /1+D+D ² +D ³ +D ⁴

G2/G3＝1+D ² +D ⁴ /1+D+D ² +D ³ +D ⁴

G3/G3=1

This results in 474 coded bits {C(0)...C(473)}, defined by:

r(k)=u(k)+r(k-1)+r(k-2)+r(k-3)+r(k-4)

C(3k)=r(k)+r(k-1)+r(k-3)+r(k-4)

C(3k+1)=r(k)+r(k-2)+r(k-4)

C(3k+2)=u(k) For k=0,1,...,153

and (for the encoder's termination):

r(k)=0

C(3k)=r(k)+r(k-1)+r(k-3)+r(k-4)

C(3k+1)=r(k)+r(k-2)+r(k-4)

C(3k+2)=r(k-1)+r(k-2)+r(k-3)+r(k-4) for k=154, 155, ..., 157

Table 7

TCH/AFS 6.7 codec:

A block of 140 bits {u(0)...u(139)} is encoded using a 1/4 rate convolutional coding defined by the following polynomial:

G1/G3＝1+D+D ³ +D ⁴ /1+D+D ² +D ³ +D ⁴

G2/G3＝1+D ² +D ⁴ /1+D+D ² +D ³ +D ⁴

G3/G3=1

G3/G3=1

This results in 576 coded bits {C(0)...C(575)}, defined by:

r(k)=u(k)+r(k-1)+r(k-2)+r(k-3)+r(k-4)

C(4k)＝r(k)+r(k-1)+r(k-3)+r(k-4)

C(4k+1)=r(k)+r(k-2)+r(k-4)

C(4k+2)=u(k)

C(4k+3)=u(k) for k=0,1,....139

r(k)=0 for k<0

And (for the encoder's termination):

r(k)=0

C(4k)＝r(k)+r(k-1)+r(k-3)+r(k-4)

C(4k+1)=r(k)+r(k-2)+r(k-4)

C(4k+2)=r(k-1)+r(k-2)+r(k-3)+r(k-4)

C(4k+3)=r(k-1)+r(k-2)+r(k-3)+r(k-4) for k=140,141,...,143

The codes are truncated in such a way that the following 100 bits are not sent: C(1), C(3), C(7), C(11), C(15), C(27), C( 39), C(55), C(67), C(79), C(95), C(107), C(119), C(135), C(147), C(159), C( 175), C(187), C(199), C(215), C(227), C(239), C(255), C(267), C(279), C(287), C( 291), C(295), C(299), C(303), C(307), C(311), C(315), C(319), C(323), C(327), C( 331), C(335), C(339), C(343), C(347), C(351), C(355), C(359), C(363), C(367), C( 369), C(371), C(375), C(377), C(379), C(383), C(385), C(387), C(391), C(393), C( 395), C(399), C(401), C(403), C(407), C(409), C(411), C(415), C(417), C(419), C( 423), C(425), C(427), C(431), C(433), C(435), C(439), C(441), C(443), C(447), C( 449), C(451), C(455), C(457), C(459), C(463), C(465), C(467), C(471), C(473), C( 475), C(479), C(481), C(483), C(487), C(489), C(491), C(495), C(497), C(499), C( 5O3), C(505), C(507) and C(511).

Table 8

TCH/AFS 5.9 codec:

A block of 124 bits {u(0)...u(123)} is encoded using a 1/4 rate convolutional coding defined by the following polynomial:

G4/G6＝1+D ² +D ³ +D ⁵ +D ⁶ /1+D+D ² +D ³ +D ⁴ +D ⁶

G5/G6＝1+D+D ⁴ +D ⁶ /1+D+D ² +D ³ + ⁴ +D ⁶

G6/G6=1

G6/G6=1

This results in 520 coded bits {C(0)...C(519)}, defined by:

r(k)=u(k)+r(k-1)+r(k-2)+r(k-3)+r(k-4)+r(k-6)

C(4k)＝r(k)+r(k-2)+r(k-3)+r(k-5)+r(k-6)

C(4k+1)=r(k)+r(k-1)+r(k-4)+r(k-6)

C(4k+2)=u(k)

C(4k+3)=u(k) For k=0, 1, ..., 123

r(k)=0 for k<0

And (for the encoder's termination):

r(k)=0

C(4k)＝r(k)+r(k-2)+r(k-3)+r(k-5)+r(k-6)

C(4k+1)=r(k)+r(k-1)+r(k-4)+r(k-6)

C(4k+2)=r(k-1)+r(k-2)+r(k-3)+r(k-4)+r(k-6)

C(4k+3)＝r(k-1)+r(k-2)+r(k-3)+r(k-4)+r(k-6) For k=124, 125, .. ., 129

The codes are truncated in such a way that the following 44 bits are not sent: C(0), C(1), C(3), C(5), C(7), C(11), C( 15), C(31), C(47), C(63), C(79), C(95), C(111), C(127), C(143), C(159), C( 175), C(191), C(207), C(223), C(239), C(255), C(271), C(287), C(303), C(319), C( 327), C(331), C(335), C(343), C(347), C(351), C(359), C(363), C(367), C(375), C( 379), C(383), C(391), C(395), C(399), C(407), C(411) and C(415).

Table 9

TCH/AFS 5.15 codec:

A block of 109 bits {u(0)...u(108)} is encoded using a 1/5 rate convolutional coding defined by the following polynomial:

G1/G3＝1+D+D ³ +D ⁴ /1+D+D ² +D ³ +D ⁴

G1/G3＝1+D+D ³ +D ⁴ /1+D+D ² +D ³ +D ⁴

G2/G3＝1+D ² +D ⁴ /1+D+D ² +D ³ +D ⁴

G3/G3=1

G3/G3=1

This results in 565 coded bits {C(0)...C(564)}, defined by:

r(k)=u(k)+r(k-1)+r(k-2)+r(k-3)+r(k-4)

C(5k)=r(k)+r(k-1)+r(k-3)+r(k-4)

C(5k+1)=r(k)+r(k-1)+r(k-3)+r(k-4)

C(5k+2)=r(k)+r(k-2)+r(k-4)

C(5k+3)=u(k)

C(5k+4)=u(k) For k=0,1,...,108

r(k)=0 for k<0

And (for the encoder's termination):

r(k)=0

C(5k)=r(k)+r(k-1)+r(k-3)+r(k-4)

C(5k+1)=r(k)+r(k-1)+r(k-3)+r(k-4)

C(5k+2)=r(k)+r(k-2)+r(k-4)

C(5k+3)=r(k-1)+r(k-2)+r(k-3)+r(k-4)

C(5k+4)=r(k-1)+r(k-2)+r(k-3)+r(k-4) for k=109,110,...,112

The codes are truncated in such a way that the following 89 bits are not transmitted: C(0), C(4), C(5), C(9), C(10), C(14), C( 15), C(20), C(25), C(30), C(35), C(40), C(50), C(60), C(70), C(80), C( 90), C(100), C(110), C(120), C(13O), C(140), C(150), C(160), C(170), C(180), C( 190), C(200), C(210), C(220), C(230), C(240), C(250), C(260), C(270), C(280), C( 290), C(300), C(310), C(315), C(320), C(325), C(330), C(334), C(335), C(340), C( 344), C(345), C(350), C(354), C(355), C(360), C(364), C(365), C(370), C(374), C( 375), C(380), C(384), C(385), C(390), C(394), C(395), C(400), C(404), C(405), C( 410), C(414), C(415), C(420), C(424), C(425), C(430), C(434), C(435), C(440), C( 444), C(445), C(450), C(454), C(455), C(460), C(464), C(465), C(470), C(474), C( 475), C(480) and C(484).

Table 10

TCH/AFS 4.75 codec:

A block of 101 bits {u(0)...u(100)} is encoded using a rate 1/5 convolutional coding defined by the following polynomial:

G4/G6＝1+D ² +D ³ +D ⁵ +D ⁶ /1+D+D ² +D ³ +D ⁴ +D ⁶

G4/G6＝1+D ² +D ³ +D ⁵ +D ⁶ /1+D+D ² +D ³ +D ⁴ +D ⁶

G5/G6＝1+D+D ⁴ +D ⁶ /1+D+D ² +D ³ +D ⁴ +D ⁶

G6/G6=1

G6/G6=1

This results in 535 coded bits {C(0)...C(534)}, defined by:

r(k)=u(k)+r(k-1)+r(k-2)+r(k-3)+r(k-4)+r(k-6)

C(5k)=r(k)+r(k-2)+r(k-3)+r(k-5)+r(k-6)

C(5k+1)=r(k)+r(k-2)+r(k-3)+r(k-5)+r(k-6)

C(5k+2)=r(k)+r(k-1)+r(k-4)+r(k-6)

C(5k+3)=u(k)

C(5k+4)=u(k) for k=0,1,...,100

r(k)=0 for k<0

And (for the encoder's termination):

r(k)=0

C(5k)=r(k)+r(k-2)+r(k-3)+r(k-5)+r(k-6)

C(5k+1)=r(k)+r(k-2)+r(k-3)+r(k-5)+r(k-6)

C(5k+2)=r(k)+r(k-1)+r(k-4)+r(k-6)

C(5k+3)=r(k-1)+r(k-2)+r(k-3)+r(k-4)+r(k-6)

C(5k+4)＝r(k-1)+r(k-2)+r(k-3)+r(k-4)+r(k-6) For k=101, 102, .. ., 106

The code is truncated in such a way that the following 59 bits are not sent: C(0), C(5), C(15), C(25), C(35), C(45), C( 55), C(65), C(75), C(85), C(95), C(105), C(115), C(125), C(135), C(145), C( 155), C(165), C(175), C(185), C(195), C(205), C(215), C(225), C(235), C(245), C( 255), C(265), C(275), C(285), C(295), C(305), C(315), C(325), C(335), C(345), C( 355), C(365), C(375), C(385), C(395), C(400), C(405), C(410), C(415), C(420), C( 425), C(430), C(435), C(440), C(445), C(450), C(455), C(459), C(460), C(465), C( 470), C(475) and C(479).

The RATSCCH long frame adopts different formats in the TCH block shown in FIG. 4 . RATSCCH is used in two cases. It is used for long frame synchronization at the very beginning of the connection between the mobile phone and the base station. Also, in some difficult cases, in-band messages in the RATSCCH are used to provide encoder mode information together with the in-band messages of regular frames. The RATSCCH used in the present invention can be compared with the format widely used in the GSM/3G system to notify the PS/CS to change the AMR mode and category.

In one embodiment, the interleaving of the long frame data for sending in the standard PHS 5ms burst is implemented in the manner shown in FIG. 5 . The bits of the long frame are interleaved as shown in Table 11.

Table 11

For interleaving, the bits are split into even and odd bits 102, 104 and interleaved according to the table. Eight segments 106 of 80-bit data are obtained at 108 , which are then interleaved with eight segments from the preceding 20 ms segment 110 . After interleaving, two segments are sent at a time in a TCH block of a PHS slot.

In the conventional data transmission mode, the system works in a similar manner to AMR in GSM and 3GPP systems. As shown in Figure 6, in the mobile phone 36, the voice encoder 38 for inputting voice samples the data and encodes The data of the channel encoder 40 is provided to the channel encoder 40, which converts the long frame into a PHS format 5ms frame for transmission. The uplink voice data is then sent to the base station 42, and in the base station 42, the channel decoder 44 will The PHS standard frame is disassembled into a long frame format, which is then passed to the speech decoder 46. During decoding, bit errors and corresponding SNRs (relative channel conditions) are estimated by the Viterbi decoder during convolutional decoding. When After making an estimate in a certain period, the codec adaptation unit 48 decides whether the coding mode should be changed in the receive direction (this will be described in detail later). The request message (uplink node command 50) is inserted into the in-band area and transmitted to the mobile phone.

The operation of the downlink data from the base station to the handset is comparable to speech data encoded by a speech encoder 52 for incoming speech which samples the data and provides the encoded data to a channel encoder 54 which Convert long frames to PHS format 5ms frames for sending. The downlink voice data is then sent to the handset where the channel decoder 56 breaks down the PHS standard frame into a long frame format which is then passed to the speech decoder 58 . During decoding, bit errors and corresponding SNRs (relative channel conditions) are estimated. After making an estimate in a certain period, the codec adaptation unit 60 makes a decision as to whether the coding mode should be changed in the receive direction. The request message (downlink node command 62) is inserted into the in-band area and transmitted to the base station.

For each long frame transmitted, the encoding mode (index) of the transmitter is determined based on the mode command using an algorithm to shift the mode based on the classes shown in Figures 7a and 7b. The PHS standard requirements allow a simplified algorithm for mode adjustment on standard GSM/3G systems. Neighboring patterns are in different classes that effectively partition the total number of patterns, as shown in the table in Fig. 7a. As shown in Figure 7b, if the transmission is in mode 11 and category 1 (12.2kbps), and the error estimate from the convolutional decoder indicates that the bit rate needs to be reduced, the mode command causes a mode in the same category to be shifted down 72, i.e. move to Mode 10 Category 1 (7.95kbps). If the BER is still too high, the command moves down a second time 74 to Mode 01 Category 1 (6.7kbps). The BER is still too high causing another shift down 76 to mode 00 category 1 (5.15kbps). If the BER is still too high, a final cross-class move 78 to mode 00 class 2 (4.74kbps) is performed. Thus, the entire range of available modes spans 4 command moves. Similarly, if the BER is reduced below a predetermined threshold, the command is moved up the category to increase the sending speed. For example, if the system is already in the lowest mode, i.e. in mode 00 category 2 (4.74kbps), and the BER is now improved, the command moves up 80 modes to mode 01 category 2 (5.9kbps), rather than going back to mode 00 category 1. A further improvement results in a move 82 to Mode 10 Category 2 (7.4kbps), and a still further improvement results in a move 84 to Mode 11 Category 2 (10.2kbps). If further improvement is available, the algorithm causes the mode to be moved 86 across classes, ie to mode 11 class 1 (12.2kbps) for the highest transmission speed. Improvement or deterioration of BER in the middle of the class range results in an up or down move within the class, as shown by moves 88 and 90 . The algorithm allows for cyclical movement based on patterns within a class, where movement to a class occurs only when the minimum or maximum sending capability in the class is reached.

Having described the invention in detail above, those skilled in the art will recognize modifications and substitutions to the specific embodiments disclosed herein as required by the patent laws. Such modifications are within the scope and intent of the invention as defined in the appended claims.

Claims (10)

1. encode and error correction method for one kind, may further comprise the steps:

From a plurality of Legacy System frames, peel off header data with head and traffic channel TCH data block;

Collect and interior speech data of the essentially identical period of period of a plurality of time slots;

With the header data coding growth frame header that separates;

To described encoded speech data;

Speech data behind described long frame header and the coding is combined into long frame;

Described long frame is deconstructed into a plurality of equal segmentations; And

Described segmentation is sent as the form of TCH data with described Legacy System frame.

2. the method for claim 1, the coding of wherein said speech data comprise and adopt the AMR codec.

3. the method for claim 1, the wherein said header data that separates comprise that the gentle slow phase of Channel Identifier closes control data.

4. the method for claim 1, the coding of the wherein said header data that separates comprise uses fixedly convolution coder.

5. method as claimed in claim 2, wherein said AMR codec has various modes and described method also comprises the step of selecting codec mode based on channel quality.

6. method as claimed in claim 4, wherein said convolution coder are 1/2 convolution coders.

7. method as claimed in claim 5, the step of wherein said preference pattern be included in BER when worsening in a classification to Move Mode down, when the minimum classification limit, stride classification and move, when BER improves, in a classification, upwards move, and when the highest classification limit, stride classification and move.

8. encode and error correction system for one kind, comprising:

Be used for peeling off the device (20) of header data from a plurality of Legacy System frames with head and traffic channel TCH data block (12a, 12b, 12c, 12d);

Be used to collect with the essentially identical period of the period of a plurality of time slots in the device (18) of speech data;

The device (20) that is used for header data coding growth frame header that to separate;

Be used for device (24) to described encoded speech data;

Be used for the speech data behind described long frame header and the coding is combined into the device of long frame (32);

Be used for described long frame is deconstructed into the device of a plurality of equal segmentations (34a, 34b, 34c, 34d); And

Be used for described segmentation as the device of TCH data with the form transmission of described Legacy System frame.

9. coding as claimed in claim 8 and error correction system, the coding of wherein said speech data comprise employing AMR codec (18), and it has various modes, and described system also comprises the device that is used for selecting based on channel quality codec mode.

10. coding as claimed in claim 9 and error correction system, wherein at the described device that is used for selecting codec mode, also comprise and being used for when BERization in a classification to Move Mode (72,74,76) down, and when the minimum classification limit, stride the device that classification moves (78), in a classification, upwards move (80,82,84) with being used for when BER improves, and when the highest classification limit, stride the device that classification moves (86).

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