Passive network multi-user access method and related device

Abstract

The application discloses a passive network multi-user access method and related devices, comprising: a reader real-time detects the tag density in the network to determine the scene type; when the average access user number is less than the spread spectrum code capacity, then a one-time high-power excitation access is adopted; when the average access user number is greater than the spread spectrum code capacity, then a layered excitation strategy access is adopted, the method and related devices can flexibly select the excitation mode according to the tag density, and optimize the system performance.

Description

Technical Field

[0001] This invention belongs to the field of passive network communication technology, and relates to a passive network multi-user access method and related devices. Background Technology

[0002] In large-scale passive tag networks, the increasing number of tags and the increasing complexity of application scenarios present numerous challenges to passive tag network access. Traditional multiple access methods such as TDMA (Time Division Multiple Access), FDMA (Frequency Division Multiple Access), and CDMA (Code Division Multiple Access) have significant drawbacks: TDMA has relatively low inventory efficiency, and the guard interval is affected by the SFO (Sampling Frequency Offset) after clock calibration; FDMA is affected by the large SFO of the equipment, leading to a decrease in bit error rate, complex frequency resource management, and increased equipment power consumption; CDMA, due to the limited capabilities of passive equipment (such as large SFO / CFO) and cost factors, is prone to code orthogonality destruction, increased inter-device interference, and reduced spectral efficiency.

[0003] Existing technologies lack an effective mechanism for dynamically adjusting based on tag density when handling tag concurrency conflicts and signal interference. For example, conflict resolution efficiency is low in high-density scenarios, while energy utilization is not optimized in low-density scenarios, resulting in system performance failing to meet diverse needs. Therefore, there is an urgent need for a multi-user access method that can flexibly select the excitation method based on tag density to optimize system performance. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a passive network multi-user access method and related apparatus. This method and related apparatus can flexibly select the excitation method according to the tag density and optimize system performance.

[0005] To achieve the above objectives, this invention discloses a passive network multi-user access method, comprising:

[0006] The reader detects the tag density in the network in real time to determine the scene type;

[0007] When the average number of access users is less than the spreading code capacity, a one-time high-power excitation access is adopted.

[0008] When the average number of access users exceeds the spreading code capacity, a tiered incentive strategy is adopted for access.

[0009] A further improvement of the passive network multi-user access method of the present invention is as follows:

[0010] Furthermore, the process of accessing the hierarchical incentive strategy is as follows:

[0011] The reader broadcasts a radio frequency signal with power P1 to activate the first-layer tag that is closer in distance. After receiving the radio frequency activation signal, the first-layer tag modulates its own ID information onto the radio frequency activation signal and then reflects it back to the reader through the antenna. The reader parses the signal to obtain the ID information of the first-layer tag and completes the discovery of the first-layer tag. The reader sends a silence command to control the first-layer tag to enter a silent state. Then the reader broadcasts a radio frequency signal with power P2 to activate the second-layer tag that is farther away, and repeats the above tag response and identification process until all layers of tags are accessed.

[0012] Furthermore, P2 > P1.

[0013] Furthermore, the process of one-time high-power excitation connection is as follows:

[0014] The reader directly broadcasts a high-power radio frequency signal to excite all tags within its range at once; the tags respond synchronously and send their ID information. The reader identifies the tags through a spreading code mechanism, which uses chip energy detection.

[0015] Furthermore, it also includes: when access fails, a retransmission and power adjustment mechanism is used to re-access the device.

[0016] Furthermore, the process of reconnecting using the retransmission and power adjustment mechanism is as follows:

[0017] When access fails, the retransmission power is dynamically adjusted based on the signal power detected initially. If the initial detection power is low and the attempt fails, a high-power retransmission is used. If the power is high but the attempt fails, a low-power retransmission is used. If the power is extremely low, it is determined that there are no users on the channel, and access attempts are stopped. At the same time, a different spreading code is used during retransmission.

[0018] Furthermore, the process of providing a one-time high-power excitation connection also includes:

[0019] Based on the signal strength P received by the tag r All tags are divided into strong signal groups and weak signal groups;

[0020] Priority is assigned to each tag within the strong signal group and the weak signal group, and the tags are sent according to the priority.

[0021] This invention discloses a passive network multi-user access system, comprising:

[0022] The judgment module is used by the reader to detect the tag density in the network in real time in order to determine the scene type;

[0023] The first access module is used to perform a one-time high-power excitation access when the average number of access users is less than the spreading code capacity.

[0024] The second access module is used to employ a hierarchical incentive strategy for access when the average number of access users exceeds the spreading code capacity.

[0025] The present invention discloses a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the passive network multi-user access method.

[0026] The present invention discloses a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the passive network multi-user access method.

[0027] The present invention has the following beneficial effects:

[0028] In specific operation, the passive network multi-user access method and related devices described in this invention employ a one-time high-power excitation access when the average number of access users is less than the spreading code capacity, and a hierarchical excitation strategy when the average number of access users is greater than the spreading code capacity. The excitation strategy is dynamically switched through over-density detection. In high-density scenarios, hierarchical excitation avoids signal conflicts, while in low-density scenarios, one-time high-power excitation improves efficiency, meeting the needs of multiple scenarios such as smart logistics, factories, and retail.

[0029] Furthermore, in this invention, layered excitation combined with silent instructions isolates identified tags layer by layer, reducing cross-layer interference; the retransmission and code-changing mechanism reduces random access conflicts and accelerates transmission convergence.

[0030] Furthermore, in this invention, secondary power consumption is avoided in low-density scenarios, and power is controlled in layers in high-density scenarios, thereby reducing the power consumption of the reader and tag while ensuring the recognition rate. Attached Figure Description

[0031] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0032] Figure 1 This is a schematic diagram illustrating the composition of a passive multi-user tag network in an embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram showing the coverage range of different power signals in an embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram of the frame structure in an embodiment of the present invention;

[0035] Figure 4 This is a schematic diagram of label priority division in an embodiment of the present invention. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] In the description of this invention, it should be understood that the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0038] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0039] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Additionally, the character " / " in this invention generally indicates that the preceding and following objects have an "or" relationship.

[0040] It should be understood that although terms such as first, second, third, etc., may be used in the embodiments of the present invention to describe the preset range, these preset ranges should not be limited to these terms. These terms are only used to distinguish the preset ranges from one another. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0041] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0043] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0044] The passive network multi-user access method of the present invention includes the following steps:

[0045] Scene detection and power strategy selection: The reader detects the tag density in the network in real time and compares the tag density with a preset threshold to determine the scene type; when the average number of accessing users is less than the spreading code capacity, a one-time high-power incentive access is adopted; when the average number of accessing users is greater than the spreading code capacity, a hierarchical incentive strategy is adopted.

[0046] The hierarchical incentive strategy access process is as follows: In high-density scenarios, the reader broadcasts a radio frequency signal with power P1 to incentivize the first-layer tags that are closer in distance; after receiving the radio frequency incentive signal, the first-layer tag modulates its own ID information onto the radio frequency incentive signal and then reflects it back to the reader through the antenna. The reader parses the signal to obtain the ID information of the first-layer tag, thus completing the discovery of the first-layer tag; the reader sends a silence command to control the first-layer tag to enter a silent state; then the reader broadcasts a radio frequency signal with power P2 (P2 > P1) to incentivize the second-layer tags that are farther in distance, and repeats the above tag response and recognition process until all layers of tags are accessed;

[0047] The process of one-time high-power excitation access is as follows: In low-density scenarios, the reader directly broadcasts a high-power radio frequency signal to excite all tags within the range at once; the tags respond synchronously and send ID information; the reader identifies the tags through the spreading code mechanism, which uses chip energy detection and the logical operation between multi-user spreading codes is "AND operation";

[0048] Retransmission and power adjustment mechanism: When access fails, the retransmission power is dynamically adjusted according to the signal power detected initially; if the initial detection power is low and unsuccessful, high power retransmission is used; if the power is high but unsuccessful, low power retransmission is used; if the power is extremely low, it is determined that there are no users on the channel and access attempts are stopped; at the same time, a different spreading code is used during retransmission.

[0049] In this embodiment, the process of one-time high-power excitation access also includes:

[0050] Power packet communication: The tag determines the signal strength P based on the received signal strength. r It is divided into a "strong signal group" and a "weak signal group"; when P r <P th The label will then be classified into the "weak signal group," blocking P. r ≥P th The tags will be divided into "strong signal groups" and processed first.

[0051] Priority ranking within a group: A priority parameter P is randomly generated. i P i =random(1,2) k+1 ), where k is the number of retransmissions; within each group of tags, time slots are allocated according to priority, with higher priority tags being sent first;

[0052] Multi-user encoding and concurrent decoding: The tag uses a spreading code to encode and modulate the ID information, and sends the signal to the reader. The reader uses a multi-user decoding algorithm to separate the signal, decode the signal one by one, extract the tag's ID information and store it.

[0053] Retransmission processing: When the reader / writer fails to decode, the retransmission power is adjusted according to the spreading code detection power; the P is adjusted according to the signal group collision status. th Threshold power; adjust the retransmission count, incrementing the retransmission count k by 1 during retransmission, and adjusting the priority parameter P. i The scope is expanded, and the number of tags allocated to a single time slot is reduced; a code-switching strategy is adopted to select different codes from the spreading codes for transmission.

[0054] In this embodiment, the reader detects tag density by monitoring the number of tags accessing the network in real time and comparing it with the preset spreading code capacity to determine the tag density scenario type.

[0055] In this embodiment, in the hierarchical excitation access process, the excitation power of each tag increases sequentially according to the distance, and the difference between the excitation power of two adjacent tags is set according to the actual application scenario.

[0056] In this embodiment, during the retransmission process, P is adjusted. th At threshold power, when there is severe conflict in strong signal groups, increase P. th Reduce the number of labels within a group; when there is severe conflict in a weak signal group, reduce P. th Reduce the number of tags within a group.

[0057] Example 1

[0058] This embodiment is applied to a smart logistics warehouse scenario, specifically a high-density scenario.

[0059] Scene detection: When goods arrive in the warehouse in a concentrated manner, if the reader detects that the tag density is higher than the threshold, the hierarchical incentive strategy will be triggered.

[0060] First-level incentives: such as Figure 2 As shown, the reader broadcasts a radio frequency (RF) signal with a power of P1. After receiving the RF excitation signal, each tag in the first layer modulates its own ID information onto the RF signal and reflects it back to the reader via the antenna. At this point, the reader obtains the ID information of the first-layer tags, completing the discovery of the first-layer tags. The reader parses the ID information, records it, and sends a silence command to silence the first-layer tags.

[0061] Second-level excitation: The reader broadcasts an RF signal with a power of P2 (P2 > P1) to excite the shelf tags (second layer) that are farther away, repeating the identification and silent process until all tags are connected.

[0062] Example 2

[0063] This embodiment is used for small-scale retail inventory scenarios, specifically low-density scenarios.

[0064] Scene detection: The retail store has few products and the label density is below the threshold, so a one-time high-power excitation is used.

[0065] One-time high-power excitation: The reader broadcasts a high-power signal, covering the entire tag network and stimulating all tags.

[0066] The frame structure of the signal is as follows Figure 3 As shown, the instruction control field indicates that the current signal is an excitation signal, stimulating the entire tag network. P th The threshold power field indicates the power threshold for tag packets, used for subsequent tag packets. The retransmission count k field indicates the number of retransmissions during failed decoding, used for subsequent tag priority allocation and tag synchronization responses.

[0067] Power packet communication: The tag determines the signal strength P based on the received signal strength. r They are divided into "strong signal group" and "weak signal group". When P r <P th The labels are divided into the "weak signal group". If P r ≥P th If the signal is strong, the label is classified as a "strong signal group". Strong signal groups are processed first to reduce the risk of weak signals being masked.

[0068] Priority ranking within a group: A priority parameter P is randomly generated. i for:

[0069] P i =random(1,2) k+1 )

[0070] Where k = number of retransmissions, Figure 4 The image shows the priority order of the tags. Strong signal groups have higher priority than weak signal groups. Within each tag group, time slots are allocated according to priority, with higher priority tags being sent first.

[0071] Multi-user encoding and concurrent decoding: The tag uses spread spectrum code to encode and modulate the ID information and sends the signal to the reader. The reader uses a multi-user decoding algorithm to separate the signal, decode the signal one by one, extract the tag ID information and store it.

[0072] The retransmission process is as follows:

[0073] When the reader / writer fails to decode, the retransmission power is adjusted according to the spreading code detection power. If the spreading code detection power is low and the access fails, it indicates that the user is far away, and a high-power signal is used for retransmission; if the spreading code detection power is high but the transmission fails, it indicates that the user is close, and a low-power signal is used for retransmission; if the power is extremely low, it is determined that there is no user accessing the channel.

[0074] Adjust P according to the signal group conflict situation. th Threshold power, strong signal group collision is severe, increase P th Reduce the number of labels within a group; weak signal groups experience severe conflicts, so reduce P. th Reduce the number of tags within a group.

[0075] Adjust the retransmission count. When retransmitting, increment the retransmission count k by 1 (initial value is 0). The priority parameter P... i The scope is expanded to: P i =random(1,2) k+1 The number of tags allocated to a single time slot is reduced, thus lowering the decoding difficulty.

[0076] By adopting a code-switching strategy, different codes are selected from the spreading codes for transmission. After a transmission collision, the code is randomly switched. This can reduce the probability of collisions by taking advantage of the decrease in the number of remaining users, accelerate transmission convergence, and improve communication efficiency.

[0077] Example 3

[0078] The passive network multi-user access system of the present invention includes:

[0079] The judgment module is used by the reader to detect the tag density in the network in real time in order to determine the scene type;

[0080] The first access module is used to perform a one-time high-power excitation access when the average number of access users is less than the spreading code capacity.

[0081] The second access module is used to employ a hierarchical incentive strategy for access when the average number of access users exceeds the spreading code capacity.

[0082] The module division in this embodiment is illustrative and represents only one logical functional division. In actual implementation, other division methods may be used. Furthermore, the functional modules in each embodiment of this application can be integrated into a single processor, exist as separate physical entities, or be integrated into a single module. The integrated modules described above can be implemented in hardware or as software functional modules.

[0083] Example 4

[0084] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps of a passive network multi-user access method, for example, including: a reader / writer continuously detecting tag density in the network to determine the scenario type; when the average number of accessing users is less than the spreading code capacity, using a one-time high-power excitation access; when the average number of accessing users is greater than the spreading code capacity, using a hierarchical excitation strategy access. The memory may include main memory, such as high-speed random access memory, and may also include non-volatile memory, such as at least one disk storage device. The processor, network interface, and memory are interconnected via an internal bus, which can be an industry-standard architecture bus, a peripheral component interconnection standard bus, an extended industry-standard architecture bus, etc., and the bus can be divided into an address bus, a data bus, a control bus, etc. The memory stores the program; specifically, the program may include program code, which includes computer operation instructions. The memory may include main memory and non-volatile memory, and provides instructions and data to the processor.

[0085] Example 5

[0086] A computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of the passive network multi-user access method. For example, the method includes: a reader / writer continuously detecting tag density in the network to determine the scenario type; when the average number of accessing users is less than the spreading code capacity, using a one-time high-power excitation access strategy; and when the average number of accessing users is greater than the spreading code capacity, using a hierarchical excitation strategy for access. Specifically, the computer-readable storage medium includes, but is not limited to, volatile memory and / or non-volatile memory. The volatile memory may include random access memory and / or cache memory, etc. The non-volatile memory may include read-only memory, hard disk, flash memory, optical disk, magnetic disk, etc.

[0087] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product implemented on one or more computer-usable storage media containing computer-usable program code.

[0088] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0089] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0090] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0091] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and disclosure of the invention. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0092] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

[0093] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for multi-user access in a passive network, characterized in that, include: The reader detects the tag density in the network in real time to determine the scene type; When the average number of access users is less than the spreading code capacity, a one-time high-power excitation access is adopted. When the average number of access users exceeds the spreading code capacity, a tiered incentive strategy is adopted for access. The process of implementing the hierarchical incentive strategy is as follows: The reader broadcast power is The radio frequency (RF) signal excites the first-layer tag, which is closer in distance. Upon receiving the RF excitation signal, the first-layer tag modulates its ID information onto the RF excitation signal and reflects it back to the reader via its antenna. The reader parses the signal to obtain the ID information of the first-layer tag, completing the discovery of the first-layer tag. The reader then sends a silence command to control the first-layer tag to enter a silent state. Finally, the reader broadcasts a signal with a power of [missing information]. The radio frequency signal excites the second-layer tag that is farther away, and repeats the above tag response and recognition process until all layers of tags are connected; The process of connecting a high-power excitation device in one go is as follows: The reader directly broadcasts a high-power radio frequency signal to excite all tags within its range at once; the tags respond synchronously and send their ID information. The reader identifies the tags through a spreading code mechanism, which uses chip energy detection.

2. The passive network multi-user access method according to claim 1, characterized in that, 3. The passive network multi-user access method according to claim 1, characterized in that, Also includes: When access fails, a retransmission and power adjustment mechanism is used to reconnect.

4. The passive network multi-user access method according to claim 3, characterized in that, The process of reconnection using retransmission and power adjustment mechanisms is as follows: When access fails, the retransmission power is dynamically adjusted based on the signal power detected initially. If the initial detection power is low and the attempt fails, a high-power retransmission is used. If the power is high but the attempt fails, a low-power retransmission is used. If the power is extremely low, it is determined that there are no users on the channel, and access attempts are stopped. At the same time, a different spreading code is used during retransmission.

5. The passive network multi-user access method according to claim 1, characterized in that, The process of connecting a one-time high-power excitation also includes: Based on the signal strength received by the tag All tags are divided into strong signal groups and weak signal groups; Priority is assigned to each tag within the strong signal group and the weak signal group, and the tags are sent according to the priority.

6. A passive network multi-user access system, characterized in that, include: The judgment module is used by the reader to detect the tag density in the network in real time in order to determine the scene type; The first access module is used to perform a one-time high-power excitation access when the average number of access users is less than the spreading code capacity. The second access module is used to employ a hierarchical incentive strategy for access when the average number of access users exceeds the spreading code capacity. The process of implementing the hierarchical incentive strategy is as follows: The reader broadcast power is The radio frequency (RF) signal excites the first-layer tag, which is closer in distance. Upon receiving the RF excitation signal, the first-layer tag modulates its ID information onto the RF excitation signal and reflects it back to the reader via its antenna. The reader parses the signal to obtain the ID information of the first-layer tag, completing the discovery of the first-layer tag. The reader then sends a silence command to control the first-layer tag to enter a silent state. Finally, the reader broadcasts a signal with a power of [missing information]. The radio frequency signal excites the second-layer tag that is farther away, and repeats the above tag response and recognition process until all layers of tags are connected; The process of connecting a high-power excitation device in one go is as follows: The reader directly broadcasts a high-power radio frequency signal to excite all tags within its range at once; the tags respond synchronously and send their ID information. The reader identifies the tags through a spreading code mechanism, which uses chip energy detection.

7. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the passive network multi-user access method as described in any one of claims 1-5.

8. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the passive network multi-user access method as described in any one of claims 1-5.

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