JP2001168904A - Method and system for co-simulating physical layer and mac layer in wireless system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simulation method and system that simulates both the physical layer and the medium access control layer in a wireless system. SOLUTION: This method for simulating a wireless packet communication system relating to one aspect this method and system includes a step where a packet is generated according to at least one probability distribution, a step where some of generated packets are selected as loss packets, a step where alive packets are processed by using a discrete event simulation and a step, where a throughput characteristic is decided by the discrete event simulation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and apparatus for simulating a communication system, and more particularly, to a co-simulation (co-simulation) of a physical layer and a medium access control (MAC) layer in a packet conversion multiple access wireless communication system. simulation) for performing a simulation.

[0002]

2. Description of the Related Art As shown in FIG. 1, a conventional packet radio system has a multi-layer structure and a radio-dependent physical layer (phys).
ical, radio-dependent layer) 10 and a medium access control (MAC) layer 12. Other layers are logical link con
trol; LLC) layer 14 and network layer 16, the latter being a mobility management (MM) 1
8, a radio transmission unit (RT) 20 and a call control unit (CC) 22 are included.
There are also higher layers 24 controlled by the user, such as the application layer (not shown in FIG. 1).

In the radio-dependent physical layer 10, a signal is transmitted from a transmitter to a receiver by wireless communication. The analog / digital processing in the physical layer is performed using the meter clock (VC
O: voltage-controlled oscillator), from which the sampling rate, symbol rate, and, depending on the system, the carrier frequency is obtained. The clock unit manages the processing timing. Thereby, samples and symbols are periodically transmitted from the transmitter and processed by the receiver.

On the other hand, the MAC layer 12 controls medium access in a multiple access environment to ensure consistency of packet communication. The processing of the MAC layer 12 is event driven, and is not managed by a periodic clock. That is, when a particular event occurs, another series of events is triggered.

In order to efficiently analyze, model, and predict the performance and interaction of the entire wireless system, simulations for both the physical layer 10 and the MAC layer 12 are required.

A typical wireless system 26, as shown in FIG. 2, has a number of terminals 28, which are at different distances from one or more base stations 30 and which are located on the Internet. And may be part of a larger network such as a public switched data network.

[0007] Terminal 28 communicates data packets 32,34 to and from base station 30 via wireless links 36,38. Each terminal 28 is arbitrarily movable, for example, as shown by an arrow 40. The moving direction and speed of each terminal 28 need not be constant. In some cases, an obstacle 42 exists between the terminal 28 and the base station 30, multipath interference by the reflector 44 occurs,
(It is not limited to this), and radio interference may occur.

[0008]

When simulating a network such as a wireless digital packet network 26 having a network layer structure as shown in FIG. 1, a system designer or engineer may use different simulations for each of the various communication layers shown in FIG. You have to consider that there are requirements.

In the conventional simulation method, it is general to perform a time-driven simulation on the physical layer 10 and an event-driven simulation on the MAC layer 12. Therefore, simulation of a network such as the wireless digital packet network 26 is time-consuming and inefficient.

Therefore, there is a need for a method and apparatus for simulating a multi-layer communication system at higher speed and more efficiently. In particular, wireless packet-switched multiple access systems
There is a need for a method and apparatus that combines simulations for at least both the physical and MAC layers of a system.

Provided below in one embodiment of the present invention is a method for simulating a wireless packet communication system, comprising: generating a packet according to at least one probability distribution; Selecting some as lost packets, processing the remaining packets using a discrete event simulation, and determining a throughput characteristic from the discrete event simulation.

As will be described below, in the present invention, by incorporating the statistics obtained by the time-driven simulation into the event-driven simulation, simulation is performed on at least both the physical layer and the MAC layer.
An efficient simulation method and apparatus can be provided.

[0013]

FIG. 3 shows an embodiment of the present invention. This figure shows a method for efficient simulation of a wireless digital packet network such as the wireless system of FIG.

As shown in the flowchart 46 of FIG.
Initializing the multiple user workspace (step 48), each of the multiple user terminals 28 and one or more base stations 30
Is simulated. In this initialization step, the data source is used to store
Or data obtained from calculations performed using partial specifications, or from a combination of these sources, may be manually entered by the person performing the simulation.

Next, a "snapshot" of the multi-user workspace is obtained (step 50). This snapshot is a representation (representation) of a multi-user working space at a certain predetermined time t.

Next, a time domain representation (time) of the physical layer corresponding to the snapshot obtained in step 50
-domain representation) is determined (step 52). Moving object 2 for snapshot
8 and base transceiver stations (BTS) 3
Channel information is included in addition to spatial information such as a relative position to zero.

Some of the snapshot information is obtained by modeling the interference from other users as disturbances from a single source in a point-to-point physical layer model.

Next, for example, the following Pareto distribution (Pare
A packet is generated according to at least one probability distribution, such as to distribution (step 54).

[0019]

The Pareto distribution is obtained by cutting the length of the exponential distribution.

Each packet is subject to distortion caused by channel or receiver failures. The channel model is additive white Gaussian noise (additive white
It includes Gaussian noise (AWGN), fading, and interference from other users, and is modeled using an event-driven multi-user workspace.

The results and conditions of the modeling are supplied to a time-driven physical layer simulator, which outputs a collision probability, a probability of false alarm, a detection probability (pr
quality of service (Qualit, such as obability of detection)
Simulation of performance related to y of Service (QoS) is performed (step 56).

By measuring the above parameters, the user can evaluate the link quality of the audio or video application. Using a table obtained by analysis and experiment, mapping between link performance such as packet loss and packet delay and voice and video quality is performed. Also, simulation of packet loss is possible. This can be done by selecting packets that are expected to be lost during transmission. In this simulation, when different specifications are input to the physical layer, the effect of the different specifications on the throughput can be examined.

Each of the terminals to be simulated has a buffer driven by a discrete event simulator. The buffer processes, from the generated packets, those of the simulated packets remaining after a loss has occurred. Used when Each simulation terminal processes its own corresponding packet. The statistics of the buffer size, such as the average number of packets in the buffer and their waiting times, are used to analyze the packet delay and throughput of the entire system (step 58).

The schedule of the buffered queue is also performed by the same discrete event simulator. Each buffer is modeled as a state machine, and transitions between states are scheduled by a discrete event engine. In a dynamic environment, the workspace is updated frequently (step 6).
0). A series of events are activated by a Brownian motion random number generator that models the movement of the terminal and a Poisson / Pareto random number generator that models packet arrival. The properties of the physical and MAC layers are updated seamlessly. The update process is scheduled by the DES engine and user control. If any one of the physical layer parameters changes, a new set of tables is generated. On the other hand, a change in the work space is passed to the physical layer model at a constant cycle.

In one embodiment of the invention shown in FIG. 4, simulation 46 is performed by workstation 62. The workstation 62 is, for example, a PC class computer system, and includes a system unit 64, a user input interface 66 such as a keyboard and a mouse (not shown), and a user output such as a display and a printer (not shown). An interface 63 is provided.

The system unit 64 includes an input processor 68 and a central processing unit (central processing unit).
A processing unit (CPU) 70, a memory 72, and a display processor (display processor) 74 are provided.
Those skilled in the art can conceive of a configuration that can realize the present embodiment other than the configuration illustrated in FIG.

For example, instead of preparing either or both of the display processing device 74 and the input processing device 68 as separate components, the CPU 7
0 may implement some or all of its functions.
The memory 72 shown in FIG. 4 is a storage device for storing programs and data necessary for executing the simulation 46. For example, a random access memory (RAM)
OM (read only memory), secondary storage device (for example,
Floppy disk, hard disk, optical storage device, etc.).

The simulation 46 is initialized and started by, for example, input from the user input interface 66 and processing by the CPU 70 using the memory 72. CPU 70 and memory 72
Is used to execute the processing of the simulation 46, and the result is displayed on a display or printed on a printer as necessary, thereby outputting the user output interface 63.
Is output to PC class workstation 62
Thus, the simulation 46 can be sufficiently executed efficiently.

From the foregoing description of the invention and the various embodiments, it is apparent that various embodiments of the invention can provide simulation methods and apparatus for performing fast and efficient multi-layer communication system simulations. It is. In particular, it is possible to provide a simulation method and apparatus that combine simulations of at least both the physical layer and the MAC layer of a wireless packet switching multiple access system.

Although the details of the present invention have been described with reference to the embodiments and the drawings, the present invention is not limited to these. Therefore, the spirit and scope of the present invention should be limited only by the appended claims.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a logical structure of a wireless digital packet network having a layer structure.

FIG. 2 is an explanatory diagram showing a state of a wireless digital packet network.

FIG. 3 is a block diagram illustrating a simulation method according to one embodiment for simulating and measuring the performance of the wireless digital packet network shown in FIG. 2;

FIG. 4 is a block diagram illustrating a simulation system according to one embodiment for performing the method illustrated in FIG. 3;

 ──────────────────────────────────────────────────の Continuing from the front page (71) Applicant 599171154 Hiroshi Harada 3-4-1 Hikarinooka, Yokosuka City, Kanagawa Prefecture Within the Ministry of Posts and Telecommunications Research Institute Yokosuka Radio Communication Research Center (71) Applicant 599171165 Genista Co., Ltd. Minato-ku, Tokyo 2-11-10 Kitaaoyama (72) Inventor Yoshihide Kamio 3-4 Hikarinooka, Yokosuka City, Kanagawa Prefecture Inside the Communications Research Laboratory, Ministry of Posts and Telecommunications Yokosuka Radio Communication Research Center (72) Inventor Hiroshi Harada 3, Hikarinooka, Yokosuka City, Kanagawa Prefecture 4th Post Office Ministry of Posts and Telecommunications Research Laboratory Yokosuka Radio Communication Research Center (72) Inventor Ahmed Bahai F-term in Algorex, Inc. 33 Wood Avenue South, Isling, NJ USA 5K030 HB19 JA05 JL01 JT09 KA02 KX11 9 A001 BB06 CC05 CC06 HH32 JJ12 JZ25 KZ56 LL08

Claims (24)

[Claims] 1. Generating packets according to at least one probability distribution; selecting some of the generated packets as lost packets; processing remaining packets using discrete event simulation And a step of determining a throughput characteristic from the discrete event simulation. 2. The method according to claim 1, wherein some of the remaining packets after the selection of the lost packet are quality of service (Qo).
The method of claim 1, further comprising varying according to statistics associated with S). 3. The method of claim 1, wherein the step of processing remaining packets using the discrete event simulation comprises simulating a plurality of terminals processing the remaining packets. 4. The step of simulating the plurality of terminals includes the step of simulating Brownian statistics.
4. The method of claim 3, wherein s) is used to simulate the movement of at least some of the terminals. 5. The method of simulating a plurality of terminals processing the remaining packets comprises simulating a buffered terminal, and further comprising determining a system packet delay. Item 4. The method according to Item 3. 6. The method of claim 3, further comprising the steps of: simulating a buffered queue at the terminal; and analyzing at least one of packet throughput and delay. The described method. 7. The method of claim 1, wherein the step of generating packets according to the at least one probability distribution comprises:
2. The method according to claim 1, wherein packets are generated at intervals simulated according to statistics. 8. The method according to claim 1, wherein the step of generating packets according to the at least one probability distribution comprises pareto statistics.
The method of claim 7, comprising generating a packet having a packet length based on tatistics. 9. Generating packets according to at least one probability distribution, selecting some of the generated packets as lost packets, processing the remaining packets using discrete event simulation, A simulation system for simulating a wireless packet communication system having a configuration for determining a throughput characteristic from an event simulation. 10. A quality of service (Qo) of some of the remaining packets after selecting the lost packet.
The simulation system according to claim 9, further comprising a configuration that changes according to statistics related to S). 11. The simulation system according to claim 9, wherein the simulation system having a configuration for processing the remaining packets using the discrete event simulation has a configuration for simulating a plurality of terminals that process the remaining packets. The described simulation system. 12. The simulation system having a configuration for simulating the plurality of terminals has a configuration for simulating the movement of at least some of the terminals using Brownian statistics. Item 12. The simulation system according to item 11. 13. A simulation system having a configuration for simulating a plurality of terminals for processing the remaining packets, further comprising a configuration for simulating a buffered terminal, and further comprising a configuration for determining a packet delay of the entire system. The simulation system according to claim 11, comprising: 14. The apparatus according to claim 11, further comprising: a configuration for simulating a queue buffered in said terminal; and a configuration for analyzing at least one of packet throughput and delay. The described simulation system. 15. The simulation system having a configuration for generating a packet according to the at least one probability distribution, further comprising a configuration for generating a packet at an interval at which a simulation is performed according to Poisson statictics. Item 10. The simulation system according to item 9. 16. A simulation system having a configuration for generating a packet according to the at least one probability distribution has a configuration for generating a packet having a packet length based on Pareto statistics. The simulation system according to claim 15, 17. A discrete event simulation, comprising: a code fragment for generating a packet according to at least one probability distribution; a generated code fragment for selecting some of the generated packets as lost packets; And a determination code fragment for determining a throughput characteristic from the discrete event simulation, wherein the computer functions as a simulation device of a wireless packet communication system. A computer-readable information recording medium on which is recorded a program for causing a computer to execute. 18. A quality of service (Qo) of some of the remaining packets after selecting the lost packet.
The information recording medium according to claim 17, further comprising a change code fragment for changing according to statistics related to S). 19. A processing code fragment for processing a residual packet using the discrete event simulation,
The information recording medium according to claim 17, further comprising a simulation execution code fragment for simulating a plurality of terminals that process the remaining packets. 20. The simulation execution code fragment for simulating the plurality of terminals comprises code fragments for simulating movement of at least some of the terminals using Brownian statistics. The information recording medium according to claim 19, wherein 21. A simulation execution code fragment for simulating a plurality of terminals processing the remaining packets includes a code fragment for simulating a buffered terminal, and determines a packet delay of the entire system. 20. The information recording medium according to claim 19, further comprising a code fragment for: 22. The apparatus further comprising: a code fragment for simulating a queue buffered at the terminal; and a code fragment for analyzing at least one of packet throughput and delay. The information recording medium according to claim 19, wherein 23. The generated code fragment for generating packets according to the at least one probability distribution comprises code fragments for generating packets at simulated intervals according to Poisson statistics. Item 18. An information recording medium according to Item 17. 24. The generated code fragment for generating a packet according to the at least one probability distribution comprises a code fragment for generating a packet having a packet length based on Pareto statistics. An information recording medium according to claim 1.