Transmission and reception of symbols in a wireless communication system

Abstract

It provides a mechanism for preparing a physical layer protocol data unit (PDU) for transmission. [Solution] A method performed by a packet transmitter includes the steps of detecting the need to transmit a second stream of symbols that has a higher priority than a first stream of symbols being transmitted from the packet transmitter to a packet receiver, inserting a dedicated tag indicating the packet from which the first stream of symbols is being preempted after the most recently transmitted symbol in the first stream of symbols, and inserting multiple symbols from the second stream of symbols after the dedicated tag to transmit the second stream of symbols to the packet receiver.

Description

Technical Field

[0001] Technical Field The embodiments presented herein relate to a method, a packet transmitter, a computer program, and a computer program product for transmitting symbols to a packet receiver in a wireless communication system. The embodiments presented herein further relate to a method, a packet receiver, a computer program, and a computer program product for receiving symbols from a packet transmitter in a wireless communication system.

Background Art

[0002] Background Industrial communication systems are typically required to deliver emergency messages with real-time constraints (e.g., emergency commands that must be processed quickly to prevent harm to people and equipment in the event of a failure). In addition to these messages, the same communication network is typically required to handle non-urgent traffic, for example, for firmware updates, system monitoring, or diagnostics. Emergency messages are usually short and can be transmitted very quickly, but non-urgent messages can be quite long and may occupy the communication channel for a long time. As a result, in industrial communication networks, there is a need for a mechanism to assign different priorities to messages and to process these messages according to their priorities.

[0003] For this reason, current communication network standards support various priority levels for exchanging packets between a packet transmitter and a packet receiver. An example of implementing packet priority is represented by the IEEE 802.11 Enhanced Distribution Coordination Function (EDCF). Accordingly, various Priorities are achieved when various traffic flows simultaneously request access to the wireless communication channel. Thereby, when a collision occurs within the queue of a packet transmitter, the contention is resolved by always transmitting the higher-priority packet first. Similar systems are also used in industrial wireless standards such as WirelessHART (registered trademark: HART is an abbreviation of "Highway Addressable Remote Transducer") and WIA-PA (abbreviation of Wireless networks for Industrial Automation-Process Automation).

[0004] Another mechanism for differentiating with respect to priorities is for adapting the Inter Frame Space (IFS) defined as the waiting time after each transmission, and this necessarily exists within the wireless network based on the channel access method of carrier-sense multiple access with collision avoidance (CSMA / CA). Therefore, the priority scheme can be realized by allocating shorter IFS to higher-priority traffic classes. Such a mechanism is used, for example, in WIA-PA. All of the above mechanisms provide some way of assigning priorities to various packets, thereby making it possible to reduce the overall waiting time for higher-priority packets. However, there are limitations shared even by these mechanisms. As an example, since there is no mechanism to stop packet transmission after starting it, a new packet may have a higher priority than the packet being transmitted

[0005] ​Even so, it is necessary to wait until the transmission of the current packet is completed. If a packet with a lower priority that is being transmitted is longer than a packet with a higher priority, a significant quality degradation of the waiting time can be expected.

[0006] In a wired industrial network, one way to overcome this problem is to implement a preemption strategy. Preemption in this context means that a packet with a higher priority can preempt the transmission of a packet with a lower priority. An example of this is disclosed in the document US7,558,269B2, according to which, in a packet transmitter, when a preemption bit is inserted into the header of an Internet protocol (IP) packet, the current packet stops and the packet receiver is notified that the transmission of a new packet with a higher priority will immediately start.

[0007] However, there is no similar mechanism for wireless networks, especially for wireless industrial communication systems. Nevertheless, such a function is required in wireless communication systems that support the transmission of multiple packets with different priorities, such as systems used for the automation of power systems.

[0008] Therefore, there is still a need to improve the mechanisms for the transmission and reception of multiple packets with different priorities.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0010] Summary The object of the embodiments in this specification is to enable efficient transmission and reception of symbols of physical layer PDUs with various priorities without causing the above problems, or at least while alleviating or reducing the above problems.

Means for Solving the Problems

[0011] According to a first aspect, a method for preparing for the transmission of a physical layer PDU is provided. The method is executed by a packet transmitter. The method includes detecting that it is necessary to transmit a second stream of symbols having a higher priority than a first stream of symbols being transmitted from the packet transmitter to a packet receiver. The method includes inserting a dedicated tag indicating a packet in which the first stream of symbols is pre-empted after the latest transmitted symbol in the first stream of symbols. The method includes inserting a plurality of symbols in the second stream of symbols after the dedicated tag to transmit the second stream of symbols to the packet receiver.

[0012] According to a second aspect, a packet transmitter for preparing for the transmission of a PDU is provided. The packet transmitter includes a processing circuit. The processing circuit is configured to cause the packet transmitter to detect that it is necessary to transmit a second stream of symbols having a higher priority than a first stream of symbols being transmitted from the packet transmitter to a packet receiver. The processing circuit is configured to cause the packet transmitter to insert a dedicated tag indicating a packet in which the first stream of symbols is pre-empted after the latest transmitted symbol in the first stream of symbols. The processing circuit is configured to cause the packet transmitter to insert a plurality of symbols in the second stream of symbols after the dedicated tag to transmit the second stream of symbols to the packet receiver. treams to the packet receiver.

[0013] According to a third aspect, a packet transmitter for preparing to transmit a PDU is provided. The packet transmitter includes a detection module configured to detect that it is necessary to transmit a second stream of symbols having a higher priority than a first stream of symbols being transmitted from the packet transmitter to a packet receiver. The packet transmitter includes an insertion module configured to insert a dedicated tag indicating a packet in which the first stream of symbols is pre-empted, after the latest transmitted symbol in the first stream of symbols. The packet transmitter includes an insertion module configured to insert a plurality of symbols in the second stream of symbols after the dedicated tag, for transmitting the second stream of symbols to the packet receiver.

[0014] According to a fourth aspect, a computer program for transmitting symbols to a packet receiver in a wireless communication system is provided. The computer program includes computer program code which, when executed on a processing circuit of a packet transmitter, causes the packet transmitter to execute the method according to the first aspect.

[0015] According to a fifth aspect, a method for receiving a physical layer PDU is provided. The method is executed by a packet receiver. The method includes receiving a first stream of symbols fragmented into a plurality of symbols. The method includes receiving a dedicated tag indicating a packet in which the first stream of symbols is pre-empted, after the latest received symbol in the first stream of symbols.

[0016] According to a sixth aspect, a packet receiver for receiving a physical layer PDU is provided. The packet receiver includes a processing circuit. The processing circuit is configured to cause the packet receiver to receive a first stream of symbols fragmented into a plurality of symbols. The processing circuit is configured to cause the packet receiver to receive a dedicated tag indicating a packet in which the first stream of symbols is pre-emphasized, after the latest received symbol among the first stream of symbols.

[0017] According to a seventh aspect, a packet receiver for receiving a physical layer PDU is provided. The packet receiver includes a receiving module configured to receive a first stream of symbols fragmented into a plurality of symbols. The packet receiver includes a receiving module configured to receive a dedicated tag indicating a packet in which the first stream of symbols is pre-emphasized, after the latest received symbol among the first stream of symbols.

[0018] According to an eighth aspect, a computer program for receiving a physical layer PDU is provided. The computer program includes computer program code that, when executed on a processing circuit of a packet receiver, causes the packet receiver to execute the method according to the fifth aspect.

[0019] According to a ninth aspect, a computer program product is provided that includes a computer program according to at least one of the fourth aspect and the eighth aspect, and a computer-readable storage medium storing the computer program. The computer-readable storage medium can be a non-transitory computer-readable storage medium.

[0020] Advantageously, these methods, these packet transmitters, these packet receivers, these computer programs, and this computer program product enable efficient transmission and reception of symbols of physical layer PDUs having various priorities.

[0021] Advantageously, in these methods, these packet transmitters, these packet receivers, these computer programs, and this computer program product, the above-described problems do not occur, or at least do not occur.

[0022] Advantageously, instead of waiting for the transmission of the current physical layer PDU to finish, the transmission of a higher-priority physical layer PDU may be started immediately after the transmission of the current symbol is completed.

[0023] Advantageously, the waiting time is significantly reduced compared to the standard approach of waiting for the transmission of the entire physical layer PDU, which can take up to several hundred microseconds or even several milliseconds at most.

[0024] Other objectives, features, and advantages of the described embodiments will become apparent from the following detailed disclosure, the appended dependent claims, and the accompanying drawings.

[0025] Generally, all terms used in the appended claims should be construed according to their ordinary meaning in the relevant art, unless specifically defined otherwise herein. References to "a / an / the element, apparatus, component, means, module, act, etc." shall be construed broadly to refer to at least one example of the element, apparatus, component, means, module, act, etc., unless otherwise specified. The acts of any method disclosed herein need not be performed in the order disclosed, unless expressly stated otherwise.

[0026] Brief Description of the Drawings Here, with reference to the accompanying drawings, the concept of the present invention will be described by way of example.

Brief Description of the Drawings

[0027]

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Best Mode for Carrying Out the Invention

[0028] Detailed Description The concept of the present invention will be more fully described hereinafter with reference to the accompanying drawings in which specific embodiments embodying the concept of the present invention are shown. However, the concept of the present invention can be embodied in many different forms and should not be construed as limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete It is provided by way of example to fully convey the scope of the concept of the present invention to those skilled in the art. Throughout the description, like numbers refer to like elements. Any operations or features indicated by dashed lines should be regarded as optional.

[0029] FIG. 1 is a schematic diagram showing a wireless communication system 100 to which the embodiments presented in this specification are applicable. In some embodiments, the wireless communication system 100 is a wireless industrial communication system. The wireless communication system 100 includes a packet transmitter (Tx) 120 and a packet receiver (Rx) 130. The packet transmitter 120 and the packet receiver 130 are configured to communicate with each other via a wireless communication channel such as a wireless channel, as indicated by reference numeral 110. In the following, without loss of generality, it is assumed that the packet transmitter 120 transmits a physical layer PDU to the packet receiver 130. In some examples, each of the packet transmitter 120 and the packet receiver 130 is part of, integrated with, or collocated with a sensor, gateway, breaker, protector, or any combination thereof in the wireless communication system 100.

[0030] As described above, in a typical wireless communication system 100, no preemption occurs when the transmission of a physical layer PDU is started. FIG. 2 schematically shows two streams 210, 220 of symbols at 200, each stream representing one physical layer PDU being transmitted, and the two streams 210, 220 of symbols being separated by a preamble 230. Thus, as shown in FIG. 2, when a higher-priority physical layer PDU enters the transmission queue of the packet transmitter 120 while the communication channel is busy, the packet transmitter 120 must wait for the completion of the ongoing (i.e., all symbols of the first physical layer PDU) transmission before starting the transmission of the symbols of the higher-priority second physical layer PDU.

[0031] The embodiments disclosed in this specification make it possible to reduce the latency of higher-priority physical layer PDUs, and in particular, rely on a customized physical (PHY) layer targeted at an industrial wireless communication system 100 with low latency and high reliability.

[0032] Orthogonal frequency-division multiplexing (OFDM) modulation applied when a bit stream of data is encoded into OFDM symbols with discontinuous numbers will be used as a specific example hereinafter. However, as those skilled in the art will understand, the embodiments disclosed in this specification are also applicable to a wireless communication system 100 that does not consider OFDM. In fact, in most wireless communication systems 100, physical layer PDUs are divided into a plurality of consecutive symbols in the time domain at the PHY layer. The shapes and lengths of these symbols are different.

[0033] Thus, the embodiments disclosed in this specification relate to a mechanism for preparing for the transmission and reception of symbols from a packet transmitter 120 in a wireless communication system 100. To obtain such a mechanism, there is provided a packet transmitter 120, a method executed by the packet transmitter 120, and a computer program product including code that, when executed on the processing circuit of the packet transmitter 120, causes the packet transmitter 120 to execute the method, for example, in the form of a computer program. To obtain such a mechanism, there is further provided a packet receiver 130, a method executed by the packet receiver 130, and a computer program product including code that, when executed on the processing circuit of the packet receiver 130, causes the packet receiver 130 to execute the method, for example, in the form of a computer program.

[0034] The embodiments disclosed in this specification are based on fragmenting the physical layer PDU into symbols in the PHY layer for preemption. Then, instead of waiting for the transmission of the symbols of the current physical layer PDU to finish, the packet transmitter 120 is configured to start transmitting the symbols of a higher-priority physical layer PDU immediately after the transmission of the current symbol of the current physical layer PDU is completed. The transmission time of a single symbol, such as an OFDM symbol, is generally very short, ranging from 4 μs in IEEE802.11g to an even shorter time in a customized system. Therefore, the waiting time is significantly reduced compared to the conventional approach of waiting for the transmission of the entire physical layer PDU, which can take up to hundreds of microseconds or even several milliseconds at most.

[0035] One problem that can occur when fragmenting a multi-symbol physical layer PDU into multiple physical layer PDUs each having one preemptable single symbol is that each symbol may not contain header information. This means that since the packet receiver 130 cannot distinguish between multiple symbols belonging to different physical layer PDUs, all symbols of the physical layer PDU must be received as a continuous stream for the packet receiver 130 to successfully decode the physical layer PDU.

[0036] Thus, according to the proposed inventive concept, a special preamble, hereinafter referred to as a dedicated tag, is inserted by the packet transmitter 120 each time a lower-priority physical layer PDU transmission is pre-empted by a higher-priority physical layer PDU. An example of such a pre-empted transmission stream is shown in FIG. 3. FIG. 3 schematically shows, at 300, two sequences of symbols with respect to the symbols. Each sequence represents one physical layer PDU being transmitted. After the preamble 230, the first part 210a of the first stream of symbols is transmitted, then the dedicated tag 240 is transmitted (for example, in the form of one or more symbols), then the second stream of symbols 220 is transmitted, and then in the second part 210b of the first stream of symbols, the remaining symbols of the first stream are transmitted. When the packet receiver 130 detects such a dedicated tag, it understands that pre-emption is in progress, pauses the processing of the received symbol stream, and starts processing the symbols of the new stream.

[0037] Referring now to FIG. 4, a method for preparing for symbol transmission, executed by the packet transmitter 120 according to one embodiment, is shown.

[0038] If it is necessary to transmit a second stream of symbols that has a higher priority than the first stream of symbols, it is assumed that the packet transmitter 120 transmits the first stream of symbols. According to the first example, the second stream of symbols is related to the control function in the wireless communication system 100, while the first stream of symbols is related to the sensor data captured in the wireless communication system 100. According to the second example, the second stream of symbols is related to the alarm event in the wireless communication system 100, while the first stream of symbols is related to the control function in the wireless communication system 100 or the sensor data captured in the wireless communication system 100. Each stream of symbols may belong to one or more corresponding physical layer PDUs transmitted from the packet transmitter 120 to the packet receiver 130. Thus, in some embodiments, each stream of symbols forms a part of the corresponding physical layer PDU. In particular, the packet transmitter 120 is configured to perform action S102.

[0039] S102: The packet transmitter 120 detects that it is necessary to transmit the second stream of symbols to the packet receiver 130. The second stream of symbols has a higher priority than the first stream of symbols being transmitted from the packet transmitter 120 to the packet receiver 130.

[0040] Fragmentation from symbol to symbol in the physical layer of the wireless communication system 100 is used to implement pre - emption. As described above, in some examples, the symbol is an OFDM symbol. A dedicated tag is inserted by the symbol transmitter to notify the packet receiver 130 that such pre - emption is being performed. As described above, in some examples, the dedicated tag is a special preamble. In some non - limiting examples, the dedicated tag is composed of a specific sequence of multiple bits (i.e., a sequence of multiple bits having a specific bit pattern) that is recognized as a dedicated tag by both the packet transmitter 120 and the packet receiver 130. For this reason, the special preamble can be composed of such a specific sequence of multiple bits. In particular, the packet transmitter 120 is configured to execute action S104.

[0041] S104: The packet transmitter 120 inserts a dedicated tag. In some examples, the dedicated tag is inserted so as to be placed in the symbol stream after the latest transmitted symbol in the first stream of symbols. The dedicated tag indicates that the first stream of symbols is pre - empted. Thus, the dedicated tag notifies the packet receiver 130 that the first stream of symbols is pre - empted.

[0042] Next, a plurality of symbols are inserted into the prioritized symbol stream. In particular, the packet transmitter 120 is configured to execute action S106.

[0043] S106: The packet transmitter 120 inserts a plurality of symbols from the second stream of symbols 220 after the dedicated tag 240 to transmit the second stream of symbols 220 to the packet receiver 130.

[0044] Here, an embodiment regarding further details of symbol transmission from the packet transmitter 120 to the packet receiver 130 in the wireless communication system 100 is disclosed.

[0045] In some scenarios, a second stream 220 of symbols is transmitted. In particular, according to one embodiment, the packet transmitter 120 is configured to perform the following (optional action S106).

[0046] S108: The packet transmitter 120 transmits the second stream 220 of symbols towards the packet receiver 130.

[0047] In some scenarios, there are more symbols of the first streams 210, 210a, 210b of symbols that need to be transmitted. Thus, according to one embodiment, any remaining symbols of the first streams 210, 210a, 210b of symbols are inserted (and transmitted) after the second stream 220 of symbols.

[0048] There may be various ways to mark the end of the last symbol of the first stream of symbols. According to one embodiment, a predetermined number of symbols of the second stream of symbols are inserted after a dedicated tag. Both the packet transmitter 120 and the packet receiver 130 recognize this predetermined number. In some examples, the value of the predetermined number is fixed. In other examples, the value of the predetermined number is communicated in advance from the packet transmitter 120 to the packet receiver 130 (or at least at the start of the transmission of a plurality of symbols of the second stream of symbols). In other scenarios, a second dedicated tag is inserted after the last symbol of the second stream of symbols. Upon detecting this second dedicated tag, the packet receiver 130 knows that the next symbol belongs to the first stream of symbols. Inserted. Upon detecting this second dedicated tag, the packet receiver 130 knows that the next symbol belongs to the first stream of symbols.

[0049] Further aspects, examples and embodiments regarding the packet transmitter 120 are disclosed below. Referring now to FIG. 5, a method for receiving symbols from packet transmitter 120 in wireless communication system 100, performed by packet receiver 130 according to one embodiment, is shown.

[0050] As described above, if it is necessary to transmit a second stream of symbols with a higher priority than the first stream of symbols, it is assumed that packet transmitter 120 transmits the first stream of symbols. In this case, further, it is assumed that packet receiver 130 receives this first stream of symbols. Therefore, packet receiver 130 is configured to perform actions S202, S204.

[0051] S202: Packet receiver 130 receives the first stream of symbols. As described above, the first stream of symbols is fragmented into symbols.

[0052] S204: Packet receiver 130 receives dedicated tag 240 after the most recently received symbol in the first stream of symbols. The dedicated tag indicates that the first stream of symbols has been preempted. Thus, the dedicated tag notifies packet receiver 130 that the first stream of symbols has been preempted.

[0053] An embodiment regarding further details of receiving symbols from packet transmitter 120 in wireless communication system 100, performed by packet receiver 130, is disclosed herein.

[0054] In some aspects, packet receiver 130 receives a plurality of symbols in the second stream of symbols after the dedicated tag. In particular, according to one embodiment, packet receiver 130 is configured to perform the following (optional) action S206.

[0055] S206: The packet receiver 130 receives a plurality of symbols from the second stream 220 of symbols after the dedicated tag 240. As described above, the second stream of symbols is fragmented into symbols.

[0056] In some scenarios, the packet receiver 130 finally receives all the remaining symbols from the first stream of symbols. Thus, according to one embodiment, all the remaining symbols from the first streams 210, 210a, 210b of symbols are received by the packet receiver 130 after a plurality of symbols from the second stream 220 of symbols.

[0057] As described above, there can be various ways to mark the end of the last symbol in the first stream of symbols. According to one embodiment, a predetermined number of symbols from the second stream of symbols are received after the dedicated tag. Both the packet transmitter 120 and the packet receiver 130 recognize this predetermined number. As described above, in other scenarios, a second dedicated tag is inserted after the last symbol in the second stream of symbols. When this second dedicated tag is detected, the packet receiver 130 knows that the next symbol belongs to the first stream of symbols.

[0058] Next, further scenarios and embodiments regarding the packet transmitter 120 and the packet receiver 130 will be described. and embodiments will be described.

[0059] The packet receiver 130 can continuously scan the stream of symbols regarding the dedicated tag being received in each physical layer PDU. According to one embodiment, when such a dedicated tag is detected, the processing according to the flowchart of FIG. 6 is executed.

[0060] S301: The packet receiver 130 detects a preamble. S302: The packet receiver 130 checks whether a stream of symbols (referred to above as the first stream of symbols belonging to another physical layer PDU) is being processed. If it is being processed, it proceeds to action S303; if not, it proceeds to action S304.

[0061] S303: The packet receiver 130 starts normal physical layer PDU processing for the symbol after the dedicated tag.

[0062] S304: The packet receiver 130 checks whether the detected preamble is the above-mentioned dedicated tag. If it is the dedicated tag, it proceeds to action S305; if not, it proceeds to action S306.

[0063] S305: The packet receiver 130 signals a scheduling error and the ongoing physical layer PDU processing is interrupted.

[0064] S306: The packet receiver 130 sends a "PDU interrupt" signal to the functional block within the packet receiver 130 that processes the address in the RAM, as a result of which a new stream of symbols with a higher priority can occupy an address space different from that of the stream of symbols being processed.

[0065] S307: The symbol after the dedicated tag is processed and stored in the new address space. S308: When all symbols in the stream of symbols with a higher priority have been processed, an "interrupt completion" signal is sent to the address processing block and the processing of the original stream of symbols with a lower priority is resumed.

[0066] After the PDU is processed, the data content of the symbol is written into the RAM that can be accessed by both hardware and software. To distinguish between the data of the stream of symbols with lower priority and the data of the stream of symbols with higher priority, the data of these two streams are written to different addresses in the RAM. This can be addressed by sending the "PDU interrupt" signal and the "interrupt completion" signal to the address processing block. However, when the processing of the physical layer PDU starts, all incoming symbols will be interpreted as data. Therefore, the above-mentioned dedicated tags will still be interpreted as data for the physical layer PDU with lower priority because its processing starts before the transmission of the "PDU interrupt" signal. To solve this problem, as shown in the flowchart of FIG. 7, when the "PDU interrupt" signal is received (S401), the address processing block first moves the pointer back by one symbol to discard the dedicated tag (S402), stores the current address pointer (S403), moves the address pointer to the start of the next PDU (S404), increments the address pointer until the "interrupt completion" signal is detected, and then returns the address pointer to the storage location (S405).

[0067] The address interruption process enables the packet receiver 130 to switch between different symbol streams and store information regarding the partially decoded physical layer PDU. Since the software layer is not notified about this behavior until the physical layer PDU is fully decoded, there is no need to recognize the symbol-level fragmentation or preemption mechanism.

[0068] The first stream of symbols may be preempted in the physical layer itself or in a protocol layer above the physical layer. The aspects related to this will be disclosed here with reference to FIGS. 8 and 9.

[0069] ​The preemption mechanism is implemented at the physical layer (i.e., protocol layer 1), where the baseband generates symbols from a byte stream coming in from an input buffer in the upper layer (i.e., a protocol layer higher than protocol layer 1: hereinafter referred to as the virtual layer). The packet transmitter 120 of this alternative example is schematically shown in FIG. 8. This alternative example requires that the packet transmitter 120 has two baseband modules 128a and 128b connected to two input buffers 127a and 127b. One is for the high-priority byte stream 260, and the other is for the low-priority byte stream 260, and the selector 129a is connected to the antenna. In this case, the selector is configured to switch between the two baseband modules when preemption is required. The first symbol among the high-priority symbol stream 220 that is prioritized over the low-priority symbol stream 210 is a dedicated tag 240 required by the packet receiver 130 to recognize that preemption is in progress.

[0070] Alternatively, preemption is directly realized in the virtual layer. Thus, in some embodiments, the packet is fragmented at the byte level. The packet transmitter 120 for this alternative example is schematically shown in FIG. 9. The selector 129b is configured to switch from the byte stream 270 coming in from the low-priority buffer 127a to the byte stream 280 coming in from the high-priority buffer 127b. For this reason, according to this alternative example, only one baseband module 128a is required. A dedicated tag 290 is inserted at the head of the high-priority byte stream 280 to make the packet receiver 130 recognize that preemption is in progress. In this alternative example, it may be possible to reduce the usage frequency of hardware resources (for example, only one baseband module) and shorten the preemption time (since typically a byte is shorter than a symbol).

[0071] Figure 10 schematically shows the components of packet transmitter 120 according to one embodiment with respect to several functional units. Processing circuit 122 can execute software instructions stored in a computer program product 1210a (such as in FIG. 12) in the form of, for example, a storage medium 126, and is a suitable central processing unit (CP U), provided using any combination of one or more of a multiprocessor, a microcontroller, a digital signal processor (DSP), etc. Processing circuit 122 may further be provided as at least one application specific integrated circuit (ASIC) or a field programmable gate array (FPGA).

[0072] In particular, processing circuit 122 is configured to cause packet transmitter 120 to perform a set of operations or actions as described above. For example, storage medium 126 may store the set of operations, and processing circuit 122 may be configured to retrieve the set of operations from storage medium 126 and cause packet transmitter 120 to perform the set of operations. The set of operations may be provided as a set of executable instructions. Thus, processing circuit 122 is thereby configured to execute the methods disclosed herein.

[0073] Storage medium 126 may also include persistent storage, which can be, for example, any one or a combination of magnetic memory, optical memory, solid state memory, or even remote mounted memory.

[0074] Packet transmitter 120 may further include a communication interface 124 for communication with packet receiver 130. Thus, communication interface 124 may include one or more transmitters and receivers comprising analog and digital components.

[0075] The processing circuit 122 controls the overall operation of the packet transmitter 120, for example, by sending data and control signals to the communication interface 124 and the storage medium 126, by receiving data and reports from the communication interface 124, and by retrieving data and instructions from the storage medium 126. Other components and related functions of the packet transmitter 120 are not described herein so as not to obscure the concepts presented herein.

[0076] FIG. 11 schematically shows the components of a packet receiver 130 according to one embodiment with respect to several functional units. The processing circuit 132 is provided using any combination of one or more suitable central processing units (CPUs), multiprocessors, microcontrollers, digital signal processors (DSPs), etc. that can execute software instructions stored in a computer program product 1210b in the form of, for example, a storage medium 136 (as in FIG. 12). The processing circuit 132 may further be provided as at least one application specific integrated circuit (ASIC) or field programmable gate array (FPGA).

[0077] In particular, the processing circuit 132 is configured to cause the packet receiver 130 to perform a set of operations or actions as disclosed above. For example, the storage medium 136 may store the set of operations, and the processing circuit 132 may be configured to retrieve the set of operations from the storage medium 136 and cause the packet receiver 130 to perform the set of operations. The set of operations may be provided as a set of executable instructions. Thus, the processing circuit 132 is thereby configured to execute the methods disclosed herein.

[0078] The storage medium 136 may also include persistent storage that can be, for example, any one or a combination of magnetic memory, optical memory, solid state memory, or even remote mounted memory.

[0079] The packet receiver 130 may further include a communication interface 134 for communication with the packet transmitter 120. As such, the communication interface 134 may comprise one or more transmitters and receivers comprising analog and digital components.

[0080] Processing circuitry 132 controls the overall operation of packet receiver 130, for example, by sending data and control signals to communications interface 134 and storage medium 136, receiving data and reports from communications interface 134, and retrieving data and instructions from storage medium 136. Other components and associated functionality of packet receiver 130 are not described in order to avoid obscuring the concepts presented herein.

[0081] FIG. 12 shows an example of a computer program product 1210a, 1210b comprising computer readable means 1230. The computer readable means 1230 may include The computer-readable means 1230 may store a computer program 1220a, which can cause the processing circuit 122 and entities and devices operatively coupled thereto, such as the communication interface 124 and the storage medium 126, to perform the methods according to the embodiments described herein. Thus, the computer program 1220a and / or the computer program product 1210a may provide a means for performing any of the actions of the packet transmitter 120 as disclosed herein. The computer-readable means 1230 may store a computer program 1220b, which can cause the processing circuit 132 and entities and devices operatively coupled thereto, such as the communication interface 134 and the storage medium 136, to perform the methods according to the embodiments described herein. Thus, the computer program 1220b and / or the computer program product 1210b may provide a means for performing any of the actions of the packet receiver 130 as disclosed herein.

[0082] In the example of FIG. 12, computer program products 1210a, 1210b are shown as optical discs such as compact discs (CDs), digital versatile discs (DVDs), or Blu-ray discs. Computer program products 1210a, 1210b can also be embodied as memories such as random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), or electrically erasable programmable read-only memory (EEPROM). and more specifically can be embodied as non-volatile storage media of devices in external memories such as universal serial bus (USB) memories or flash memories such as compact flash (registered trademark) memories. For this reason, computer programs 1220a, 1220b are schematically shown here as tracks on the illustrated optical disc, and computer programs 1220a, 1220b can be stored in any manner suitable for computer program products 1210a, 1210b.

[0083] The concepts of the present invention have been mainly described with reference to several embodiments. However, as will be readily understood by those skilled in the art, other embodiments other than those disclosed above are equally achievable within the scope of the concepts of the present invention as defined by the appended claims.

Claims

1. A method for preparing the transmission of a physical layer protocol data unit (PDU), said method being executed by a packet transmitter (120), comprising: detecting (S102) that it is necessary to transmit a second stream (220) of symbols having a higher priority than a first stream (210, 210a, 210b) of symbols being transmitted from said packet transmitter (120) to a packet receiver (130); inserting (S104) a dedicated tag (240) indicating a packet in which the first stream (210, 210a, 210b) of symbols is pre-empted, after the latest transmitted symbol among the first stream (210, 210a, 210b) of symbols; inserting (S106) a plurality of symbols among the second stream (220) of symbols, after said dedicated tag (240), for transmitting said second stream (220) of symbols to said packet receiver (130).

2. The method according to claim 1, further comprising transmitting (S108) said second stream (220) of symbols towards said packet receiver (130).

3. The method according to claim 1, wherein all remaining symbols among the first stream (210, 210a, 210b) of symbols are inserted after said second stream (220) of symbols.

4. The method according to claim 1, wherein a predetermined number of symbols among the second stream (220) of symbols are inserted after said dedicated tag (240).

5. A method for receiving a physical layer protocol data unit (PDU) from a packet transmitter (120), said method being executed by a packet receiver (130), comprising: receiving (S202) a first stream (210, 210a, 210b) of symbols fragmented into symbols; receiving (S204) a dedicated tag (240) indicating a packet in which the first stream (210, 210a, 210b) of symbols is pre-empted, after the latest received symbol among the first stream (210, 210a, 210b) of symbols.

6. The method according to claim 5, further comprising the step (S206) of receiving a plurality of symbols among the second stream (220) of the symbols fragmented into symbols after the dedicated tag (240).

7. The method according to claim 6, wherein all of the remaining symbols among the first streams (210, 210a, 210b) of the symbols are received after the plurality of symbols among the second stream (220) of the symbols.

8. The method according to claim 5, wherein a predetermined number of symbols among the second stream (220) of the symbols are received after the dedicated tag (240).

9. The method according to any one of claims 1 to 8, wherein the plurality of symbols are OFDM symbols.

10. The method according to any one of claims 1 to 9, wherein the dedicated tag (240) is a special preamble.

11. The method according to any one of claims 1 to 10, wherein a plurality of packets including the plurality of symbols are fragmented at the byte level.

12. The method according to any one of claims 1 to 11, wherein the first stream (210, 210a, 210b) of the symbols is pre-emphasized in the physical layer itself or in a protocol layer higher than the physical layer.

13. The method according to any one of claims 1 to 12, wherein each stream of a plurality of symbols is part of a corresponding physical layer PDU.

14. The method according to any one of claims 1 to 13, wherein each of the packet transmitter (120) and the packet receiver (130) is a sensor, a gateway, a breaker, a protector, or any combination thereof in a wireless communication system (100).

15. The method according to claim 14, wherein the wireless communication system (100) is a wireless industrial communication system (100).

16. A packet transmitter (120) for preparing for the transmission of a physical layer protocol data unit PDU, comprising a processing circuit (122), the processing circuit causing the packet transmitter (120) to, Detect that it is necessary to transmit a second stream (220) of symbols having a higher priority than a first stream (210, 210a, 210b) of symbols being transmitted from the packet transmitter (120) to the packet receiver (130), Insert a dedicated tag (240) indicating a packet in which the first stream (210, 210a, 210b) of the symbols is pre-empted after the latest transmitted symbol among the first stream (210, 210a, 210b) of the symbols, A packet transmitter (120) that inserts a plurality of symbols among the second stream (220) of the symbols after the dedicated tag (240) in order to transmit the second stream (220) of the symbols to the packet receiver (130).

17. A packet receiver (130) for receiving a physical layer protocol data unit PDU, comprising a processing circuit (132), the processing circuit causing the packet receiver (130) to, Receive a first stream (210, 210a, 210b) of symbols fragmented into symbols, A packet receiver (130) that receives a dedicated tag (240) indicating a packet in which the first stream (210, 210a, 210b) of the symbols is pre-empted after the latest received symbol among the first stream (210, 210a, 210b) of the symbols.

18. A computer program (1210a) for preparing to transmit a physical layer protocol data unit PDU, including computer code, the computer code, when executed on a processing circuit (122) of a packet transmitter (120), causing the packet transmitter (120) to, Detect that it is necessary to transmit a second stream (220) of symbols having a higher priority than a first stream (210, 210a, 210b) of symbols being transmitted from the packet transmitter (120) to the packet receiver (130) (S102), Insert a dedicated tag (240) indicating a packet in which the first stream (210, 210a, 210b) of the symbols is pre-empted after the latest transmitted symbol among the first stream (210, 210a, 210b) of the symbols (S104), A computer program (1210a) that inserts a plurality of symbols of the second stream (220) of the symbols after the dedicated tag (240) in order to transmit the second stream (220) of the symbols to the packet receiver (130). **Claim 19** A computer program (1210b) for receiving a physical layer protocol data unit PDU, including computer code, which, when executed on a processing circuit (132) of a packet receiver (130), causes the packet receiver (130) to receive a first stream (210, 210a, 210b) of symbols fragmented into symbols (S202), receive a dedicated tag (240) indicating a packet in which the first stream (210, 210a, 210b) of the symbols is pre-empted, after the latest received symbol of the first stream (210, 210a, 210b) (S203), the computer program (1210b).

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