Interleaving of information bits

Interleaving of information bits

Technical field

The present invention relates to wireless communication. In particular, the invention relates to the interleaving of information bits for transmission over a wireless interface. The present invention can also be applied to de-interleaving the received information bits.

Background technique

A communication system is known in which a wireless interface is provided for an entity provided with a transmitter and/or receiver. The entity may include devices such as mobile or fixed user equipment (for example, mobile phones), base stations equipped with transmitters and/or receivers, and/or other devices. The communication through the wireless interface may include, for example, communication such as voice, data, and multimedia.

Communication systems typically work according to a given standard or specification, which prescribes what the various components of the system can do and how they should do it. For example, the standard or specification may define whether a user or, more accurately, a user equipment or terminal is provided with a circuit-switched service and/or a packet-switched service. It is also possible to define the communication protocol and/or parameters that will be used for the connection. It is also possible to define the hierarchical sequence of various functions associated with the communication instance. In other words, it is necessary to define a specific set of "rules" on which the communication can be based in order to be able to communicate through the system.

An example of wireless communication is the Public Land Mobile Network (PLMN). PLMN is a cellular system in which a base transceiver station (BTS) or similar entity of the radio access network of the communication system provides services to user equipment (UE) such as a mobile station (MS) through a wireless interface between these entities . A more specific example of this so-called second generation (2G) PLMN system is the Global System for Mobile Communications (GSM).

The further development of GSM is the so-called Enhanced Data Rate for GSM Evolution (EDGE). EDGE is a standard prepared by the Third Generation Partnership Project (3GPP), and is now also defined by ETSI (European Telecommunications Standards Institute). For example, the description of the GSM/EDGE radio access network (GERAN) and the channel coding used for GERAN can be found in the 3G specification TS45.003 v5.5.5 (2002-04).

EDGE can achieve higher data rates than conventional 2G GSM. This improvement included in various other modifications is achieved by making changes in the modulation.

GERAN is based on the use of TDMA (Time Division Multiple Access) transmission. In a TDMA-based system, transmission takes place in time frames. Each frame can be divided into multiple time slots. Dividing the frame into multiple time slots allows multiple users to share the frame. A TDMA frame can be regarded as a physical channel that provides a communication medium for information transmission between two nodes in a communication system. Time slots can be used for consecutive frames to form a physical channel for transmission. Then a burst is transmitted in each time slot.

A typical TDMA transmitter will include devices for performing channel coding, interleaving, burst formation, modulation, and actual transmission, see Figure 1. It should be understood that these functions may be provided by means of separate entities, or at least some of these functions may be provided by functional blocks of the transmitter.

After channel coding, the information bits form an entity called a block. The total number of bits in a block mainly depends on the selected encoder. The block is typically transmitted through multiple bursts in a time slot (that is, through multiple consecutive frames).

The information bits in the block are scattered to appropriate positions in the burst through interleaving. The goal is typically to distribute consecutive information bits as far apart as possible from each other. In the above-mentioned technical specification 3GPP TS 45.003, a diagonal interleaver is given for processing a block of 456 coded bits. The block of encoded data is the interleaver "block diagonal", where a new block is started every 4 blocks, and the data is distributed over 8 blocks. In a given interleaver: for k=0,1,2,...455b=k mod 8j=2((49k)mod57)+int[kmod84]---(1)]]> where j is The position of bit k in burst b.

If we name J the burst size (114 in the example below), K is the block size (456), O is the ordering parameter (49) and D is the interleaving depth (8), formula (1) Can be written as:

For k=0,1,2,...K-1b=kmod Dj=2((O×k)modJ2)+int[kmodD4]---(2)]]>Note: KD=J2]] > It can be considered that as long as half of the block size (K/2) cannot be divided by the interleaving depth (D), then the formula can work perfectly. This can be achieved as long as the block size K is greater than the interleaving depth D, that is: K2modD0]]> formula (3) can check whether the interleaving formula (2) works. In the above example, formula (3) will give ((456/2)mod 8)=4.

Communication systems typically have separate functions. As explained above, functions can be hierarchically divided into multiple groups. These are usually called layers. Generally, the lowest layer in the layer stack includes the actual physical transmission medium, that is, the logical service channel that provides the radio bearer for transmission. This is commonly referred to as the physical layer. One or more layers on the physical layer include functions such as wireless link control and media access control (MAC: provide unconfirmed data transmission services on logical channels and access to the transmission channel radio interface layer 2 sublayer) . Since only the physical layer is of interest in the context of understanding the present invention, any further discussion of other layers will not be made here.

Flexible Layer One (FLO) for GERAN has been proposed in the third generation partnership project (3GPP) standardization. This is a new configurable physical layer for GSM/EDGE radio access network (GERAN). The advantage of the proposed new physical layer is that functions such as channel coding and interleaving can be specified during the call establishment phase. Thus, this means that new services such as Internet Protocol (IP) Multimedia Subsystem (IMS) services can be supported without specifying a new coding scheme. Moreover, the physical layer will be more consistent with the third-generation (3G) Universal Mobile Telecommunications Service (UMTS) Terrestrial Radio Access Network (UTRAN) regulations.

The inventors found that the existing diagonal interleavers such as those described above are not easily reused for this purpose, and in order to implement this solution, a new type of diagonal interleaver needs to be specified. The reason is that this scheme frees up bits for transmission of information.

So there are some unresolved problems on this point. The most important thing is that the existing diagonal interleaver can no longer work in all situations, for example, because the 3GPP scheme enables half of the block size to be divided by the interleaving depth. That is, when the above relationship (3) is no longer satisfied, that is: K2modD=0]]>The interleaving formula (2) does not continue to work. This becomes a problem because instead of the previous 57 information bits, this scheme enables the transmission (and therefore interleaving) of 58 bits and 464 bits of block size (equal to 4 bursts). This will result in ((464/2)mod8)=0, that is, the condition (3) mentioned above is not met.

This problem is illustrated by the following simple example of the situation where the relationship (3) is not satisfied. Assuming: K=16 Block size J=4 Burst size O=1 Sorting parameter D=8 Interleaving depth can be verified by (3) ((16/2) mod 8)=0, and the corresponding condition (3) ). Table 1 shown in Figure 4 lists the values given by the interleaving formula (2) for the above specific example. As shown in Table 1, starting from the 8th bit, the interleaving formula (2) no longer works normally, because:-the 8th bit and the 0th bit are mapped to the same position and the same burst;- The ninth bit and the first bit are mapped to the same position and the same burst;-the tenth bit and the second bit are mapped to the same position and the same burst;-the eleventh bit and the third bit are mapped to the same position and the same burst Bits are mapped to the same position and the same burst;-The 12th bit and the 4th bit are mapped to the same position and the same burst;-The 13th bit and the 5th bit are mapped to the same position and the same -The 14th bit and the 6th bit are mapped to the same position and the same burst;-The 15th bit and the 7th bit are mapped to the same position and the same burst.

This may cause various problems in bit transmission and reception.

Summary of the invention

The embodiments of the present invention intend to solve the above-mentioned problems associated with interleaving in the example, so as to avoid improper mapping of information bits in bursts.

According to one aspect of the present invention, there is provided a method for interleaving information bits from a data block into transmission bursts in a transmitter, each information bit is assigned an index, and the interleaving includes calculating the information bits in transmission. The position in the burst is such that the value of the exponent of at least a part of the information bit is modified.

The modification of the index value may include offsetting the index value through an offset term. Each information bit to be included in one of the transmission bursts may be set with an index number, and the sum of the index number of each information bit and the offset term may form the index of the information bit used in the calculation. Modify the value.

In a further embodiment, it is determined whether the value of the index needs to be modified. This determination may include determining whether half of the block size can be divided by the interleaving depth.

According to another aspect of the present invention, a method for deinterleaving information bits from a received transmission burst in a receiver is provided, each information bit is assigned an index, and the deinterleaving includes: determining Whether the value of any index is modified before transmitting the transmission burst; and based on the determination, the information bits are de-interleaved according to the modified value of the index or the original assigned value of the index.

According to another aspect of the present invention, there is provided a transmitter including: an interleaver for interleaving information bits from a data block into transmission bursts, each information bit is assigned an index; and for calculating the The position of the information bit in the transmission burst so as to modify the value of the index of at least a part of the information bit before the interleaving.

According to another aspect of the present invention, there is provided a receiver including: a deinterleaver for deinterleaving information bits from a received transmission burst, each information bit being assigned an index; and For the means for determining whether any exponent is modified before transmitting the transmission burst, the deinterleaver is configured to, based on the determination, quantify the information bit according to the modified value of the exponent or the original assigned value of the exponent Perform deinterleaving.

The embodiments of the present invention can provide a device that avoids mapping too many information bits to positions in a burst. Diagonal deinterleaving can be performed even under the condition that the above equation (3) is not satisfied.

Description of the drawings

In order to better understand the present invention, now refer to the accompanying drawings by way of example, in which: Figure 1 schematically shows a transmitter device in which the present invention can be applied; Figure 2 schematically shows a transmitter device in which the present invention can be applied Figure 3 shows a flow chart of the embodiment; Figure 4 shows the table shown in accordance with the prior art interleaving formula values obtained; and Figure 5 shows the table shown in the interleaving formula according to an embodiment of the present invention The value obtained.

detailed description

Figure 1 schematically depicts certain components of a typical TDMA transmitter. More specifically, FIG. 1 shows the channel coding block 8, the interleaving block 10, the burst information block 12, the modulation block 14, and the transmission block 16 in the direction in which the signal flows through the transmitter. Following the transmitting block or radio block 16 is typically a suitable antenna device 18. Since the present invention relates to the operation of the interleaving block 10, and since those skilled in the art are familiar with the purpose and operation of other blocks, no further description will be given here.

Figure 2 schematically depicts certain components of a typical TDMA receiver. More specifically, FIG. 2 shows a receiving block 24, a modulation block 22, a de-interleaving block 20, and a channel decoding block 18 in the direction in which an information signal received through an appropriate antenna device flows through the receiver. As above, there is no need for any further explanation of the purpose and operation of blocks 18, 22, and 24.

Fig. 3 shows a flowchart according to an embodiment of the present invention. In operation, the interleaving frame 10 is set for interleaving the information bits from the data block into a transmission burst. Each bit of this information is assigned an index. Example values of the index are shown in column k of the tables of FIGS. 4 and 5.

In the interleaving process, the position of the information bit in the transmission burst is calculated. According to the principle of the present invention, the position is calculated based on the modified value of the index of at least some information bits.

Referring now also to FIG. 5, Table 2 shown is the values obtained by the embodiment of the present invention.

Except that the value of parameter j is obtained by using the modified formula (2) of diagonal interleaving, the parameters in Table 2 of Fig. 5 correspond to the parameters of Table 1 in Fig. 4. More specifically, shift terms are introduced in formula (2).

The use of the new term s can be described in more detail as follows: For k=0,1,2,...K-1b=kmod D if K2modD=0,]]> then s=int[kK/2]--- (4)]]>otherwise s=0j=D4×[(O×(k+s))modJD/4)]+int[kmodD4]---(5)]]> where j is bit k in burst The position in b.

The offset term s is activated only when half of the block size can be divided by the interleaving depth (see (4) above). In the above example, the offset term s is 0 for the first half block and 1 for the second half block.

The value 4 represents the size of the radio block. In the given example, the radio frequency block consists of 4 bursts. If a different radio frequency block is used, then the value should be changed accordingly.

In addition to introducing the offset term, the calculation for obtaining the value of the parameter j in Table 2 is performed based on the above formula (2), and is completed with the value used in the above example. It is easy to notice that because of the offset term s, the bits are no longer mapped twice at the same position in the interleaving stage (and bits 0 and 8, 1 and 9, 3 and 11 in Table 1 are like this).

When receiving a signal, for example, through the receiver device of FIG. 2, the de-interleaving block should use the same rules as above. For example, the de-interleaving block 20 knows that the index may have been modified, and therefore checks the received burst. The value of this block can clearly indicate to the receiver whether modifications such as exponential offset are used.

It should be understood that the index does not have to be composed of numbers. For example, the index value can be given by characters or strings. The string may include letters, or a combination of letters and numbers, for example.

It should also be understood that although the present invention has been described in conjunction with user equipment of a PLMN system, the embodiments of the present invention can be applied to any other suitable types of communication systems including transmitter and receiver devices.

The embodiments of the present invention have been described in the context of GSM/EDGE and TDMA systems. The present invention can also be applied to any other applicable communication systems and access technologies. Examples of other access technologies include code division multiple access, frequency division multiple access, space division multiple access, and any combination thereof.

It is also noted here that although the exemplary embodiments of the present invention are described above, various changes and modifications can be made to the disclosed solutions without departing from the scope of the present invention as defined by the appended claims.