WO2011039762A2

WO2011039762A2 - System for real-time radio / physical layer simulation

Info

Publication number: WO2011039762A2
Application number: PCT/IN2010/000586
Authority: WO
Inventors: Soma Bandyopadhyay
Original assignee: Tata Consultancy Services Ltd.
Priority date: 2009-09-07
Filing date: 2010-09-03
Publication date: 2011-04-07
Also published as: WO2011039762A3

Abstract

A system for real-time radio / physical layer simulation for data blocks which are transmitted by said system, said system comprising: - first determination means adapted to determine the data blocks to be processed per unit time (per sub-frame); - second determination means adapted to determine the seed values of the noise generation with respect to each unit processing time (per sub-frame); - third determination means adapted to determine the number of available computing nodes in a cloud computing system; - distribution means adapted to distribute said determined data blocks to be processed to a set of determined computing nodes, thereby distributing the relative processing time of data and the seed for noise generation for generating results at each of said computing nodes; and - master/scheduler computing node adapted to collects each of said results in order to generate a final simulation result.

Description

SYSTEM FOR REAL-TIME RADIO / PHYSICAL LAYER SIMULATION

FIELD OF THE INVENTION

The present invention relates to the field of telecommunications.

Particularly, this invention relates to a real-time radio / physical layer simulator based on data parallelism.

BACKGROUND OF THE INVENTION

3GPP (3^rd Generation Partnership Projects) LTE (Long Term Evaluation) is the radio technology designed to increase the capacity and speed of mobile telephone networks.

The LTE technology consists of three layers namely the Physical Layer (Layer 1), the Radio Link and Medium Access Control Layer (Layer 2), and Radio Resource Control Layer (Layer 3).

With the evolution of LTE and increasing complexity and scalability of the wireless communication networks it has become essential for using simulators to evaluate the performance of the network.

Particularly, the physical layer simulation of 3GPP LTE has processing overhead mainly in the receive path, specifically in channel decoding. As per the real-time requirement of the physical layer, the layer transmits and receives set of bits called as transport blocks from the higher layer typically, within 1 millisecond, known as one TTI (Transmission Time Interval) or sub-frame time. To achieve simulation in this layer in real time the reduction of simulation time is essential.

Therefore, there is a need for a system which can greatly reduce the overall simulation time taken for processing multiple sub-frames i.e. to process the multiple transport blocks.

PRIOR ART

US 7774440 discloses a Method and System for Enhancing Performance of a Physical Network Under Real-Time Control Using Simulation of a Reference Model. This system discloses the concept of executing a plurality of simulations for the network using parallel discrete event simulation. It also states that the simulator may also advantageously utilize parallel discrete-event simulation to obtain rapid and accurate simulation results.

Also, the simulation loop may continue on various network condition, and traffic pattern. The simulator uses a layered architecture, follows the OSI stack model. The above disclosure of US7774440 does not disclose the exact nature of cloud computing by attributing the data to be processed to nodes in a cloud computing environment or even the idea of employing a master/scheduler computing node which collects the results from the other computing nodes (client nodes) and generates a final simulation result. The disclosure of US7774440 does the prediction about network performance enhancement, and operation, under real-time control. It does not state how to reduce the simulation time of a radio layer/ physical layer and to approach towards real time simulation. It does not state about the processing of multiple transport block / sub frames, seeds of noise generation simultaneously. US2003046668 discloses a System, Method and Article of Manufacture for Distributing Ip Cores. The system includes a method of distributing cores over a network. It also discloses executing a program in relation to the distributed cores, which are analogous to the aspect of distributing the data to be processed to a set of computing nodes in a cloud computing environment, and further running a simulation for obtaining results, as disclosed in the current invention.

*

US2003046668 discloses a Method for Parallel Query Processing with Non- Dedicated, Heterogeneous Computers that is Resilient to Load Bursts and Node Failures. This invention discloses a method which entails storing data in a data storage system accessible to a plurality of computing nodes. The query fragments are independently executed on individual nodes. The query fragment results are combined into a final query result.

The above disclosure of US2003046668 does not disclose the aspect of identifying sub-frames and distributing them over the nodes of a cloud computing system or a grid computing system. Typically, the disclosure of US2003046668 is based on query processing system; it does the processing of a query in parallel in a DBMS. Here, the data is carefully partitioned across a cluster of machine, it claims that the individual computing nodes includes non- dedicated heterogeneous computing nodes each running different database application. It is not related with radio layer simulation, in the current patent application the multiple transport block is getting processed simultaneously , i.e. 'n' no of sub-frames are getting processed by 'n' no of computing nodes having a controller / master node. This master node distributes the important information like sub-frame no, size of transport block, seed for noise generation to be processed, and itself used to process the control sub-frames. The current patent application considers a cluster of computing nodes with equal processing speed, and claims reduction of simulation time by 1/nth if there is n no. of computing nodes present in the cluster.

In summary, however, the above disclosures of US7774440, US2003046668, and US2003046668 does not achieve an optimum simulation time.

OBJECTS OF THE INVENTION

It is an object of the present invention to provide an efficient system which can reduce the simulation time required for processing the transport blocks.

Another object of the present invention is to provide a distributed computing system with multiple computing nodes which can reduce the simulation time by processing multiple sub-frames simultaneously i.e. processing information bits (transport blocks in case of LTE) which are supposed to be processed in different times are processed at the same time keeping the physical layer functionality unchanged

Still another object of the present invention is to provide a system which can make the radio / physical layer simulation time faster at least by 1/η^Λ of the time taken into a single system, where 'n' is the no. of computing nodes and approaching towards real-time.

SUMMARY OF THE INVENTION

According to this invention, there is provided a distributed computing system with multiple computing nodes which can reduce the simulation time by processing multiple data blocks (sub-frames) simultaneously, thereby keeping the physical layer functionality unchanged.

The present invention envisages a system for reducing the simulation time on the 3GPP LTE physical layer simulator. Particularly, the present invention relates to a system for reduction of simulation time of the physical layer, by distributing the data to be processed to a set of computing nodes in a cloud computing environment instead of processing the data by a single computing node. In addition, along with the data, the relative processing time of data and the seed for noise generation are also distributed.

The distributor computing node is considered as master/scheduler node which is also termed as the job manager. The master/scheduler computing node collects the results from the other computing nodes (client nodes) and generates the final simulation result.

In accordance with the present invention, the system reduces the simulation time keeping the physical layer functional blocks or functionality unchanged.

Physical layer simulation is based on 3 GPP LTE physical layer standard. This standard defines unit processing time as 1 millisecond which is also known as one sub-frame time. In accordance with the present invention, the following prerequisites are required as user defined inputs in order to realize the system:

i) the total number of bits to be processed;

ii) the maximum number of bits that can be processed in 1 millisecond (maximum transport block size); iii) the complete duration of simulation in milliseconds (number of sub-frames and frames);

iv) the seed for the noise generation;

v) the modulation and coding scheme (MCS);

vi) the number of antenna ports for multiple-input and multiple-output (MIMO); and

vii) the maximum available computing nodes.

According to this invention, there is provided a system for real-time radio / physical layer simulation for data blocks which are transmitted by said system, said system comprises:

- first determination means adapted to determine the data blocks to be processed per unit time (per sub-frame);

- second determination means adapted to determine the seed values of the noise generation with respect to each unit processing time (per sub- frame);

- third determination means adapted to determine the number of available computing nodes in a cloud computing system;

- distribution means adapted to distribute said determined data blocks to be processed to a set of determined computing nodes, thereby distributing the relative processing time of data and the seed for noise generation for generating results at each of said computing nodes; and

- master/scheduler computing node adapted to collects each of said results in order to generate a final simulation result.

Typically, said second determination means includes user input means adapted to input initial seed values. Typically, said second determination means includes pre-computation means adapted to compute seed values per unit time based on a fixed seed value and maximum simulation time.

Typically, said system includes a fourth determination means adapted to determine the maximum number of bits that can be processed by said system in a defined unit of time.

Typically, said system includes a first computation means adapted to compute maximum data block size to be transmitted.

Typically, said system includes a second computation means adapted to compute duration of time for entire data block to be transmitted.

In accordance with the present invention, there is provided a method for realtime radio / physical layer simulation for data blocks which are transmitted by said system, said method comprising the steps of:

- determining the data blocks to be processed per unit time (per sub-frame);

- determining the seed values of the noise generation with respect to each unit processing time (per sub-frame);

- determining the number of available computing nodes in a cloud computing system;

- distributing said determined data blocks to be processed to a set of determined computing nodes, thereby distributing the relative processing time of data and the seed for noise generation for generating results at each of said computing nodes; and - collecting each of said results in order to generate a final simulation result.

Elaborately, the above-mentioned steps are:

1) Determining the data blocks to be processed in each unit time (per sub- frame), i.e. sizes of the .transport-blocks to be processed in one millisecond depending on the MCS (Modulation and Coding Scheme) and UE (User Equipment) category;

2) determining the seeds of the noise generation with respect to each unit processing time (per sub-frame). Typically, seeds are calculated throughout the complete simulation time based on the fixed seed value that comes as a user input. In case of LTE, seeds are calculated for all sub-frames of frames typically, consisting of 10 sub- frames, which are required for the whole simulation cycle;

3) distributing the data / number of data bits (required to be processed ) to the computing nodes along with the unit-processing-time number i.e. the sub-frame number and the frame numbers in case of LTE, for which the data will be processed. Typically, the master/scheduler/job-manager always distributes the computational intensive tasks to the computing nodes equally and accordingly determines the time unit numbers i.e. the sub-frame numbers associated to those tasks; and

4) collecting the results from the client computing nodes and generating the final simulation result. Typically, the simulation results are collected by the master. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will now be described with reference to the accompanying drawings, in which:

FIGURE 1 illustrates a schematic of radio layer simulation in a cloud computing environment; and

FIGURE 2 illustrates the usage of pre-computed seeds/states producing the same output.

DESCRIPTION OF THE INVENTION

The invention will now be described with reference to the accompanying drawings which do not limit the scope and ambit of the invention. The description provided is purely by way of example and illustration.

In accordance with the present invention, there is provided a system for reducing the simulation time required for the radio / physical layer of LTE and bringing the simulation time as close to the real-time keeping the radio / physical layer functionalities unchanged.

The system reduces the simulation time by distributing the data to be processed amongst various computing nodes in a cloud computing environment.

Cloud computing environment is used to get a set of computing nodes and one of the nodes is considered as a master/scheduler. The Master determines the number of client nodes based on the maximum available client nodes and the total number of the sub-frames required for the complete simulation, whichever is minimum (cither the total sub-frame required or maximum available client nodes).

Referring to the accompanying drawings, FIGURE 1 shows the architecture of radio/physical layer simulation system using a cloud computing system. The system comprises:

• User Interface 12;

• Job Manager/ Schedule 14; and

• Computing nodes 16 in a cloud computing system 10.

In accordance with the invention, the User Interface 12 receives the user defined inputs like MCS, UE category and the total number of bits to be processed based on the LTE 3 GPP standard. The Master/Scheduler/job-manager 14 based on these inputs determines the transport block size i.e. number of bits to be processed in unit time.

In addition, the scheduler 14 determines the seed of noise which is basically the state of the randn() function used by awgn() function to generate the noise for the channel model. The initial state or seed value is taken as user input from the User Interface 12, seed values per unit time of processing (per sub-frame time) are pre-computed by the master node 14 based on a fixed seed value with a fixed maximum simulation time and the pre computed values are distributed to the client nodes. The objective of distribution of seed is to generate and add the same noise, as that generated in case of a single system simulation-run, to the transmitted data associated with the different sub-frames as seen in FIGURE 2. The scheduler/job-manager 14 determines the sub-frame numbers to be distributed to the computing nodes 16. It distributes the computational intensive, equal weighed activities/tasks including data traffic processing and PDSCH (Physical Downlink Shared Channel) processing for LTE downlink to the computing nodes 16 and to itself and determines the respective sub-frame numbers linked to those tasks, for instance, if PDSCH data processing is required, then for 'n' sub-frames and 'n' available client nodes , master assigns l^sl sub-frame to client-node- 1, 2^nd sub- frame to client-node-2 and n^th sub-fame to client-node-n. The master node 14 follows a round-robin mechanism to assign tasks to the client nodes. Total numbers of tasks assigned to the master 14 are always greater than total tasks assigned to the client nodes 16.

In accordance with the present invention, the sub-frames where downlink/uplink data transmission and reception are occurring are distributed / allocated to the computing nodes and to the scheduler/master itself. Non data processing sub frames, where control information is exchanged and synchronization is established between downlink and uplink transmitters are processed by the job manager/master node alone, example ,these are namely the first six sub-frames which comprise the end of secondary synchronization signal exchange specific to the LTE standard.

In accordance with the present invention, at the beginning of the simulation the scheduler/master node 14 distributes the number of bits / size of the transport block to be processed, their associated sub-frames which are the various sub- frames where client nodes will do the data processing i.e. data transmission and reception, seeds of the noise for those sub-frames, RNTI (Radio Network Temporary Identifier), and cell IDs. The distribution of information is done by TCP/IP communication by using UDP (User Datagram Protocol).

Alternatively, a TCP (Transmission Control Protocol) connection or a shared storage space/file system can be used as an alternative communication mechanism to exchange the information between job manager 14 and the client nodes 16. The shared file system is the ideal case to capture the dynamic status from the computing nodes.

The client nodes 16 process the respective sub-frame's data transmission and reception based on the various functional blocks as per physical layer standard (3GPP-LTE) specification. They use allocated sub-frames appropriately, for instance sub-frame numbers are required while performing scrambling in case of LTE, simulate the channel with the exact noise factor and a known SNR (signal to noise ratio) per sub-frame, and finally send back the obtained BER (Bit Error Rate) of the processed data to the job manager/master node.

The job-manager/master-node 14 accumulates the BER sent by the client nodes and generates the simulation results based on BERs of all sub-frames and forwards the result to the user interface 12.

The technical advancements of the present invention include:

• Providing a system which reduces the simulation time by l/n* of the time taken by a single system, where 'n' is the no. of client nodes;

• providing a system where the amount of data transferred between two computing nodes is considerably less in comparison to standard cloud computing activities; • providing a distributed computing system which can reduce the simulation time by processing the transport blocks simultaneously;

• providing a system which can reduce the simulation time keeping the physical layer functional blocks / functionality unchanged;

• providing a system which reduces the simulation time by distributing the processing of the multiple sub-frames at the same time amongst various computing nodes in a cloud computing environment;

• processing multiple sub-frames simultaneously, thus keeping the physical layer functionality unchanged;

• distributing the data to be processed to a set of computing nodes in a cloud computing environment;

• distributing the relative processing time of data and the seed for noise generation; and

• employing a master/scheduler computing node which collects the results from the other computing nodes (client nodes) and generates a final simulation result

While considerable emphasis has been placed herein on the particular features of this invention, it will be appreciated that various modifications can be made, and that many changes can be made in the preferred embodiments without departing from the principles of the invention. These and other modifications in the nature of the invention or the preferred embodiments will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

Claims

Claims:

1. A system for real-time radio / physical layer simulation for data blocks which are transmitted by said system, said system comprising:

first determination means adapted to determine the data blocks to be processed per unit time (per sub-frame);

second determination means adapted to determine the seed values of the noise generation with respect to each unit processing time (per sub-frame);

third determination means adapted to determine the number of available computing nodes in a cloud computing system;

distribution means adapted to distribute said determined data blocks to be processed to a set of determined computing nodes, thereby distributing the relative processing time of data and the seed for noise generation for generating results at each of said computing nodes; and

master/scheduler computing node adapted to collects each of said results in order to generate a final simulation result.

2. A system as claimed in claim 1 wherein, said second determination means includes user input means adapted to input initial seed values.

3. A system as claimed in claim 1 wherein, said second determination means includes pre-computation means adapted to compute seed values per unit time based on a fixed seed value and maximum simulation time.

4. A system as claimed in claim 1 wherein, said system includes a fourth determination means adapted to determine the maximum number of bits that can be processed by said system in a defined unit of time.

5. Λ system as claimed in claim 4 wherein, said system includes a first computation means adapted to compute maximum data block size to be transmitted.

6. Λ system as claimed in claim 4 wherein, said system includes a second computation means adapted to compute duration of time for entire data block to be transmitted.

7. A method for real-time radio / physical layer simulation for data blocks which are transmitted by said system, said method comprising the steps of:

determining the data blocks to be processed per unit time (per sub-frame); determining the seed values of the noise generation with respect to each unit processing time (per sub-frame);

determining the number of available computing nodes in a cloud computing system;

distributing said determined data blocks to be processed to a set of determined computing nodes, thereby distributing the relative processing time of data and the seed for noise generation for generating results at each of said computing nodes; and

collecting each of said results in order to generate a final simulation result.