[pic] Summer Practical Training
At Reliance Communications, Navi Mumbai
INTRODUCTION:
MINS is an IP based solution that shall be designed to cater to a subscriber base of around 1000 subscribers. It shall support all the features and functionalities provided by the legacy switching systems.
MINS was required as the rate of the “Qualcomm chipset “for the BSC (base station controller) was rising day by day. Qualcomm company is extracting 5$ per subscriber from any Indian company for using their chipset that why in MINS, BSC is constructed not using any hardware but by binding the system by some algorithms. It means that in MINS, software is prepared which can do the work of the hardware chip for BSC instead of using that Qualcomm chipset.
The basic aim of designing of the MINS project is the removal of the Qualcomm chipset for BSC.
MINS is not the whole network; it is the part of a network which contains following networks identities. They are:-
1. BTS CONTROLLER-Base transceiver system controller
2. BSC-Base station controller
3. MSC-Mobile switching centre
4. HLR-Home location register
5. VLR-Visitor location register
MINS also contains some essential parts other than which are specified above. They may be either the parts of the four of them specified above or other ones. They should be considered in following lines as they come into the act.
Some assumptions are made preparing the MINS project. They are:-
¬ SSD (Shared secret data) is shared with the VLR, in case of Authentication.
MINS system shall work with the Soft switch MGC (Media Gateway Controller) for all the calls originating from/terminating to the PSTN or GSM networks.
SCOPE OF TRAINING
The basic scope or we can say the aim of the training was putting our theories to practice. What we have learned in two years of the B.E. degree, were put to practice. Any which we just learn as a theory subject we will forget that thing very quickly, but if we have put that thing to practice we will not forget that thing in our whole life. It is not possible for a single college to provide the practical training for all the 350 students because it is too costly to provide such machines or systems that a multinational company can provide to the trainees. I have done my summer practical training at Reliance Communication at Dhirubhai Ambani Knowledge City(DAKC), Navi Mumbai. It was a great experience to work with such great and intelligent colleagues. The whole DAKC so well designed and architect any beauty lover can’t move away from that. I think for me it was an educational tour. My training was based on MINS (Mobile integrated network system). It was a newly prepared project for wireless communication by the Reliance infocomm. MINS was a under launch product whose testing was on the way. According to the project manager of MINS it will take 2-3 yrs to launch this product. So it was not possible for us to the get the whole knowledge about the MINS so we divided our training to following phases:
• Theoretical knowledge about the networks and layers.
• Theoretical knowledge about the MINS from the document SRS_MINS which was provided by the company to us on our personal computer at Reliance Communications.
• Testing of the project –It includes the checking of the message flow between the network subsystem when a call is initiated or released.
• Preparing of the training report.
I learned a one more thing that preparing a project is just not preparing it but it includes it’s testing also which is tedious work to do.
It was very difficult for me to stay 45 days away from my family and parents. For me it was also one of the aims to recover from family fever.
It is compulsory for every student to complete training of 90 days till we complete our B.E. degree. It is done in two phases –
• 45 days after 2nd year.
• 45 days after 3rd year.
LEARNING OBJECTIVE
It was a long term training in which were thought theory about the MINS project and we worked on the testing of MINS project. In testing we worked on the UNIX operating system. MINS project team had prepared the testing environment on the operating system UNIX. They have chosen the UNIX environment as on UNIX multithreading is possible. Multithreading is process in which multiple system can work at a time.
What do we mean with a thread?
Technically, a thread is defined as an independent stream of instructions that can be scheduled to run as such by the operating system. But what does this mean?
In the UNIX environment a thread:
• Exists within a process and uses the process resources
• Has its own independent flow of control as long as its parent process exists and the OS supports it
• May share the process resources with other threads that act equally independently (and dependently)
• Dies if the parent process dies – or something similar
METHODOLGY
The project manager Mr. Praveen singhal had allotted me a computer on which we study or understand the theoretical knowledge of the MINS project using the SRS_MINS document (Software requirement document_ MINS) in our half time. After having my lunch when I came back to office then they allot me a laptop which connected to one of the subsystem of the network like BSC, BTS etc.
I have to submit a report at 6:00 p.m. every evening what we have concluded while we are testing the project.
After we put the project (MINS system) we put to a tester which they named as load test.
What we do whole day manually, is known as manual test and then when we put it to a tester is known as load test.
The flow of messages which we get in the load test can be seen in the logs of the BTS and BSC subsystem. That was work of the employees or I can say the work of my seniors or my teachers there.
When we left from there a viva voce was conducted by the project manager and we submitted the project report to them.
CONTENTS OF TRAINING
1. Initialization of the Project-(Phases)
2. Requirement of these Phases
3. Some Definitions
4. MS-Mobile system
5. Complete description of MINS
6. Call scenario of voice call flow
7. Call initiated by the MS of MINS
8. General call flow for MINS
9. Advantages of MINS
INITIALIZATION OF THE PROJECT: MINS is a very huge and lengthy project to design and launch for single man and to work on it respectively. So phases are divided and some teams are set up to make this project a grand success.
The MINS project is divided into 2 Phases listed below
Phase 1A: The Scope of Phase 1A is to demonstrate a successful Intra MINS and Inter MINS call along with CDR generation. Handoff functionality will not be supported in this phase of MINS.
Phase 1: Phase 1 will be focused on interfaces towards Billing and Mediation, NMS, Legal Interception System, and PSTN World. This phase will also have capability to interact with the prepaid system. Along with this all the bugs observed in Phase 1A will be fixed in Phase 1.
At the end of Phase 1, it will be possible to make inter MINS calls, Intra MINS Calls, Calls to PSTN world, Call to Existing Reliance Wireless Network and Send SMS on the MINS network. Also the Handoff and announcement functionality shall be supported in this Phase.
The Load test as per the Specifications will be carried out after successful demonstration of all the services and integration with the network elements present in the Reliance network.
It will include PCF functionality and integration with data network (R world), OTAF (Over The Air Functionality) and VMS (Voice Mail System). Also all the supplementary services development will be taken up in this phase. REQUIREMENT OF THESE PHASES • • Phase 1A Requirement— Feature or function that shall be supported by the system to be delivered in in the phase 1A.These are mandatory for the Intra MINS and Inter MINS call establishment. All Phase 1A requirements are flagged by the letter “PH 1A.” • • Phase 1 Requirement— Feature or function that shall be supported by the system to be delivered in the phase 1.These are mandatory for supporting Prepaid functionality, SMS functionality and calls terminating on /from PSTN or GSM network as well as to offer Supplementary services. All Phase 1 requirements are flagged by the letter “PH 1.” • • Phase 2 Requirement— Feature or function that shall be supported by the system to be delivered in the phase 2.All Phase 2 requirement are flagged by the letter “PH 2.” SOME DEFINITIONS:
Some definitions should be useful for upcoming information.
• Assured Mode. Mode of delivery that guarantees that a PDU will be delivered to the peer. A PDU sent in assured mode is retransmitted by the LAC Sublayer, up to a maximum number of retransmissions, until the LAC entity at the sender receives an acknowledgement for the PDU. See also Confirmation of Delivery
• Authentication: A procedure used to validate mobile stations or subscriber’s identity.
• Base Station. A fixed station used for communicating with mobile stations. Depending upon the context, the term base station may refer to a cell, a sector within a cell, an MSC, or other part of the cellular system. See also MSC
• Common Location Register (CLR): A proprietary node that contains the MDN and MIN ranges and the corresponding HLR addresses.
• ESN: The unique serial number of a cellular phone that identifies it to the cellular system for the purpose of placing and receiving calls.
• Home Location Register (HLR): The HLR is the location register to which a user identity is assigned for record purposes such as subscriber information (e.g. ESN, MDN, Profile Information, Current Location, and Authorization Period).
• IS-41: The network standard that allows all switches to exchange information about subscribers.
• Layer 1 (L1). Layer 1 (Physical Layer) provides for the transmission and reception of radio signals between the base station and the mobile station
• Layer 2 (L2). Layer 2 provides for delivery of signaling messages generated by Layer 3 (see below). Layer 2 consists of two sub layers: the LAC Sublayer and the MAC Sublayer (see below). Layer 2 makes use of the services provided by Layer 1
• Layer 3 (L3). Layer 3 originates and terminates signaling messages according to the semantics and timing of the communication protocol between the base station and the mobile station. Layer 3 makes use of the services provided by Layer 2
• Logical channel. A communication path between stations, described in terms of the intended use of, and access to, the transferred data, and direction of transfer. A logical channel can be “mapped” to and from one or more physical channels
• Lower Layers. In this document, layers below the LAC Sublayer (e.g., Layer 1 and the MAC Sub layer)
• MAC Sub layer. See Medium Access Control Sublayer
• Mapping. In this context, the technique for forming associations between logical and physical channels
• Message. Signaling data unit transferred between the base station and the mobile station. In this document, it should be interpreted as the Layer 3 PDU or the LAC SDU
• Medium Access Control (MAC) Sublayer. The MAC Sublayer is the lower sub layer of Layer 2. It implements the medium access protocol and is responsible for transport of LAC protocol data units using the services provided by Layer 1
• Message Control and Status Block (MCSB). In this document, a parameter block representing the interface control information transferred between Layer 3 and the LAC Sublayer. The MCSB is also used to carry relevant information within the LAC Sublayer. • MDN (Mobile Directory Number): It is a 10 digit unique number, which identify a mobile subscriber
• MIN: It is a unique 10-digit decimal number programmed into the MS. This MIN is transmitted over the air interface during registration to inform the network of the identity of the mobile station accessing the network. It is also used as a key field to access the subscriber profile record stored in the HLR
• Mobile Switching Center (MSC): A configuration of equipment that provides cellular or PCS service • MS (Mobile Station): The Mobile Station (MS) is the equipment that subscribers use to originate and receive information and calls via the wireless network. The MS provides the user with access to the radio network and performs other functions for the user
• Visitor location registers (VLR). The VLR database contains temporary information about subscribers that is needed by the mobile services switching center (MSC) in order to service visiting subscribers. When a mobile station roams into a new mobile services switching center (MSC) area, the visitor location register (VLR) connected to that MSC will request data about the mobile station from the HLR, reducing the need for interrogation of the home location register (HLR).
MS (MOBILE STATION)
The mobile station (MS) consists of the mobile equipment (the terminal) and a smart card called the Subscriber Identity Module (SIM). The SIM provides personal mobility, so that the user can have access to subscribed services irrespective of a specific terminal. By inserting the SIM card into another GSM terminal, the user is able to receive calls at that terminal, make calls from that terminal, and receive other subscribed services.
The mobile equipment is uniquely identified by the International Mobile Equipment identity (IMEI). The SIM card contains the International Mobile Subscriber Identity (IMSI) used to identify the subscriber to the system, a secret key for authentication, and other information. The IMEI and the IMSI are independent, thereby allowing personal mobility. The SIM card may be protected against unauthorized use by a password or personal identity number.
[pic]
COMPLTETE DESCRIPTION OF “MINS”
MINS is composed of the following parts which were stated in on of the above section. They are as below: - 1. BTS Controller 2. Base station controller 3. Mobile switching centre 4. Home location register 5. Visitor location register
OVERVIEW OF MINS (MOBILE INTEGRATED NETWORK SYSTEM) [pic] Description of the above parts is as follows:
1. BTS Controller-
BTS controller shall be a PowerPC based General Purpose Microcontroller residing in the BTS hardware. For the Phase 1A the BTS hardware shall be the BTS development platform made up of Commercial Off-the-Shelf (COTS) cards and associated software.
The PowerPC 8245 shall have a Real Time Operating System (RTOS) called OSE delta running on it.
The BTS controller shall perform following functions:
CDMA2000 Physical Layer Control: This function will interact closely with the Base band processing algorithms running on the Tigers ARC 201 (TS-201) DSPs.
Abis functions on the BTS side: This function involves packet sing physical layer frames into IP PDUs, open sockets and send IP PDUs to the BSC entity of MINS as per the Abis protocol. Similar functions are executed for the receipt of IP packets from BSC entity. OA&M functions for the BTS: This will broadly include the Configuration, Fault and Performance management functions. In Phase 1 A only a small subset of these functions shall be implemented. The definition of the entire set of function and this small subset is in progress.
The Base Transceiver Station houses the radio transceivers that define a cell and handles the radio-link protocols with the Mobile Station. In a large urban area, there will potentially be a large number of BTSs organize, thus the requirements for a BTS are ruggedness, reliability, portability, and minimum cost.
[pic]
2. BSC-The Base Station Controller manages the radio resources for one or more BTSs. It handles radio-channel setup, frequency hopping, and handovers, as described below. The BSC is the connection between the mobile station and the Mobile service Switching Center (MSC).
[pic]
In the construction of the BSC, there are following parts. They are as follows: 1. CP-Call processing 2. Layer 3 3. LAC 4. MAC 5. ABIS 6. Transport layer
Description of all the above stated parts is as follows: 1. Call processing (CP) – Call processing is, just like a heart to the human being, for BSC. It creates the messages which are used to be exchanged in between the BSC and BTS, BSC and MSC etc. As a example we take a ORM i.e. Origination message. Origination message contain three things mainly. They are: • IMSI-international mobile station identity • ESN-electronic serial number • MDN-mobile directory number • Other matter also
Call processing prepares the message as follows below:-
[pic]
1. Layer 3 (L3) - Following L3 signaling messages will be supported in MINS BSC Subsystem, which will be sent or received on logical channels f-csch & r-csch. Same way the user traffic messages will be carried on logical channels f-dsch & r-dsch. When message is passed to the L3 from the call processing then L3 will add a header to the message. Now message will be seen like as below: [pic]
2. LAC Sub layer- LAC Sub layer shall implement a data link protocol that provides for the correct transport and delivery of signaling messages generated by Layer 3. LAC Sub layer will also add a header to the above message.
[pic] 3. MAC Sub layer- The MAC Sub layer shall implement the medium access protocol and is responsible for transport of LAC protocol data units using the services provided by Layer 1. The MAC Sub layer shall also control the access to and from upper layer signaling, Data Services (not in phase 1A) and voice services to physical layer resources. MAC sub layer will also add a header to the above message. [pic]
4. ABIS - The Abis Interface is defined as the interface that provides signaling and traffic between Base Transceiver System (BTS) and Base Station Controller (BSC) for MINS Network. The signaling procedures on Abis are divided as follows:
• Abis Application Control Signaling those associated with O & M signaling and Abis Signaling.
• Abis Traffic Signaling are those that directly associated with a call. They include transmit and receive message to/from Mobile Station.
• Abis Transport Signaling Procedures to set up and manage the stable link between BTS and BSC.
Abis interface also add a similar header to the above message. [pic] 5. Transport layer (TL) – Transport layer is used to take the message from Abis of the BSC to the Abis of the BTS controller. 3. MSC –The MSC subsystem of the MINS will be responsible for the call routing functionalities. It will be responsible for Call processing and the Mobility management functions. In order to install, initialize and configure the Subsystem there will be an EMS function and to ensure the availability of the subsystem there will be maintenance functionality built in the system.
The central component of the Network Subsystem is the Mobile Switching Center (MSC). It acts like a normal switching node of the PSTN or ISDN, and additionally provides all the functionality needed to handle a mobile subscriber, such as registration, authentication, location updating, handovers, and call routing to a roaming subscriber. These services are provided in conjunction with several functional entities, which together form the Network Subsystem. The MSC provides the connection to the fixed networks (such as the PSTN or ISDN). Signaling between functional entities in the Network Subsystem uses Signaling System Number 7 (SS7), used for trunk signaling in ISDN and widely used in current public networks. 4. HLR (Home location register)
The HLR is a database used for storage and management of subscriptions. The home location register stores permanent data of the subscribers; including subscriber’s service profile, location information, and activity status.
HLR tracks and manages individual subscriber information that is needed by the network to confirm that callers are valid customers, to route calls, and to provision services. HLR is a centralized database application that provides call completion data for cellular subscribers. The HLR database contains the administrative information for each subscriber registered in the network, along with the subscriber’s current location. The HLR database is “dipped” whenever the switch in the mobile network requires subscriber information to complete a call. The HLR is the location register to which a user identity is assigned for record purposes such as subscriber information (e.g. ESN, MIN, MDN, Profile Information, Current Location, and Authorization Period). The HLR shall provide these two basic functions:
• It shall identify the subscribers served by the MSC.
• It shall be responsible for providing instructions/data to MSCs for MS registration, call origination and call delivery. 5. VLR (Visitor location register)
The Visitor Location Register (VLR) contains selected administrative information from the HLR, necessary for call control and provision of the subscribed services, for each mobile currently located in the geographical area controlled by the VLR. Although each functional entity can be implemented as an independent unit, all manufacturers of switching equipment to date implement the VLR together with the MSC, so that the geographical area controlled by the MSC corresponds to that controlled by the VLR, thus simplifying the signaling required. Note that the MSC contains no information about particular mobile stations --- this information is stored in the location registers.
CALLS SCENARIO OF VOICE CALL FLOW
The call scenarios that shall be supported in MINS Phase 1A can be broadly classified into the following types based on the voice path:
1) Intra-Network: These are the calls between subscribers located within the MINS network (home & roamed subscribers). These calls can further be classified into two sub-categories: I. Intra MINS: Intra MINS calls are the calls in which the voice path shall be established between A-party and B-party both belonging to the same MINS. The scenarios of this category shall be a. A11-B11 b. A11-B21 c. A12-B22 d. A12-B12 e. A21-B21 f. A11-BL1 g. A21-BL1 h. AL1-BL1 i. AL1- B11 j. AL1-B21 II. Inter MINS: Inter MINS calls are the calls in which the voice path shall be established between A-party and B-party belong to different MINS. The scenarios of this category shall be: a. A11-B22 b. A11-B23 c. A11-B12 d. A12-B11 e. A12-B21 f. AL1-B22 g. A11-BL2 h. AL1-BL2
2) Inter-Network: These are calls between MINS and other networks. The scenarios of this category shall be: A. Normal Cases: · RIM-MINS(ALL- B11) · MINS-RIM(A11-BLL) · MINS-PSTN · PSTN-MINS B. Roaming Cases : · A11-B1L · ALL-BL1 · A1L-BL1 · AL1-B2L
CALL INITIATED BY THE MS OF MINS 1. Starting of BSC and BTS 2. Successful Link establishment Between BTS and BSC 3. BTS Registration 4. Successful Mobile Originated call (for the A-party) 5. Successful mobile terminated call (for the B-party) 6. voice packets flow 7. Successful Call released
Now we start with the complete description of the call started to the call completion 1. Starting of BSC and BTS- Normally BSC and BTS are as the normal personal computer a individual is started by just switching on them. 2. Successful Link establishment Between BTS and BSC- a) The BTs and BSC have been powered on. The BTS and BSC read the Configuration file. In configuration file the BSC read the IP address of BTS and BSC itself. The BTS and BSC also has been initialized the port for the communication. b) After receiving the IP address of BTS the BSC sends the Link Status Request message to the BTS. The BSC starts timer. c) The BTS response the BSC by sending Link status Request message. The BSC stops timer after receiving the response from BSC. At this point it considered the link between BTS and BSC is up. 3. BTS Registration- a) The BTS sends the Register Request message to the BSC indicating that the BTS is available to support radio network operations. This message is repeated until a Register Response acknowledges it. b) The BSC sends the Register Response Message to the BTS if the registration is successful. From this point the BTS shall operate in the network mode. The BTS shall now be able to receive configuration information from the BSC over the Abis interface.
Now the diagrammatically BTS and BSC are shown as below on the next page.
[pic]
1. Successful Mobile Originated calls (for the A-party)—initially ms sends ORM (origination message) to BSC, then BSC create the CCR (call connection reference). That is BSC assign a reference number to every call i.e. to originated call (A party) and terminated call (B party). CCR increases up to 4294967295 calls or it is its final limit for CCR. Then normal messaging start through the stack already had been establishment between BSC and BTS controller, when they were started earlier. When Abis set up is received by BSC, When Abis set up acknowledgement is received by BTS, and then it creates some dedicated stacks. Now all messages and voice frames are sent on dedicated stacks till call is released and Abis Release Ack is not received by BTS. Now it is shown diagrammatically as on next page. Dedicated stacks are in different colour. [pic]
Here is the diagram of message flow during the successful mobile originated call. [pic]
5 Successful mobile termination call---Here are the messages flow during the process when B-part pick up the receiver of the phone or connect to the calling party i.e. A-party. [pic] 1. Voice packet flows---Any voice signal is first convert into a message using some algorithms and Walsh code. Voice signals after converted into a message are transferred as shown in the explanation of BSC subsystem
2. Successful call released by MINS Subscriber---Here shown is the message flow during the release of a voice call.
[pic]
GENERAL CALL FLOW FOR MINS SUBSCRIBER:
The call flows that shall be common to all MS present in the network are described in the general call flow from A-party to B-party. Specific scenarios arising due to the location or the condition of the MS have been covered subsequently. Call flows are divided into three sections- voice, data and message.
Voice Call Flow (BSC-MSC-HLR-BSC):
An end-to-end voice call (BSC-A to BSC-B) can be divided into the following sections: 1. Registration 2. Call Initiation 3. B-Party Locating 4. Call Connection 5. Call Termination 6. Feature Invocation (Only Call Forwarding Unconditional) 7. Deregistration 8. Profile Updated at the HLR 9. Data unreliable at the HLR
Registration
MS Initiated Registration
The MS may initiate registration for a number of reasons according to the parameters passed by the BSC.
The various conditions under which a MS gets registered with the MSC can be divided into the following four scenarios; Call flows for the same are discussed below:
i. Registration initiated by MS when in its Home Location ii. Registration initiated by MS when in Roaming Location iii. Registration initiated by MS during a call (zone change/time based). iv. Multiple Registrations with Cancellation Denied at VLR. v. Registration initiated by MS when in RIM Network vi. Registration initiated by RIM MS when in MINS Network B- Party locating
After Authorization and channel assignment A-party MSC shall try to locate the B-party serving MSC. A-party MSC shall check whether B-party belongs to its own home network (MINS) by checking whether the B-party MDN is within the MDN range defined at the MSC. It shall be static lookup table maintained in the MSC.
Note: In case of MINS the MINS IP Address, MSC IP Address, VLR IP Address and the HLR IP Address shall be the same. Each MINS shall have its own unique MSC ID. the individual nodes of MINS (MSC, BSC, HLR and VLR) shall be identified by their respective Identification Number. The combination of the MSC ID and the Identification Number shall be unique to identify a particular subsystem of the MINS. This combination shall be used to check the validity of the network element
Intra MINS Call
If B-party belongs to the originating MINS system, then MSC shall directly send “LOCREQ” to the HLR, else MSC shall query CLR to find the MINS IP Address and Home HLR-ID of B-party. Then, the “LOCREQ” message shall be sent to the B-Party Home HLR. Between MSC and CLR there will be flow of proprietary information.
At the B-party HLR, it shall be checked whether the A-party Current MSC is the same as the B-party Current MSC. If yes, then no “ROUTREQ” message shall be sent and the HLR shall send the “locreq” message towards the MSC. In this case it shall include the B-party MDN as the TLDN for that particular call.
The “LOCREQ” message contains Bill ID (Billing Id), Dialed Digits (B party MDN), A party MSC-ID etc. The “locreq” return result message contains the following parameters – MIN, ESN, and MSCID. After getting the “locreq” message, the B-party serving MSC shall check whether the TLDN received is defined in its Routing Table. If yes, then no paging procedure shall be initiated. If no, then the Serving MSC (B-Party) shall send a “Paging Request” message to the Serving BSC (B-party). The BSC (B-party) shall find out the exact location of the B-party and then return the “Paging Response” message to the Serving MSC (B-party).
The “Paging Request” message contains the parameters—MIN, ServiceOption etc. The “Paging Response” message contains the parameters – B-party’s MIN, ESN, User Zone ID, the Service Option etc .
If the “Paging Request” fails (Timer expiry), the B-party serving MSC shall try again and restart the timer, configurable number of times. If the BSC fails to receive an “Assignment Request” message or “Clear Command” message in response to the “Paging Response” message prior to the expiration of timer T303, then it shall send a “Reorder” or “Release” message to the B-party MS, and shall clear all the associated resources
Inter network
RIM to MINS:
[pic] Inter Network call – RIM - MINS
MINS to RIM
[pic]
Inter Network Call - MINS-RIM
i. MINS to PSTN – Since the called party is PSTN subscriber, there is no procedure for B-party locating. Refer section
ii. PSTN to MINS
[pic] Inter Network call – PSTN - MINS Call Connection
The B-party serving MSC shall send the “Assignment Request” message towards the B-party serving BSC, to request for allocation of radio resources. This shall also include the port number of the MSC for the BSC to use for voice path establishment. After allocating the radio resources for that particular request, the B-party serving BSC shall respond by sending “Assignment Complete” message towards the B-party serving MSC. This shall also include the port number of the BSC for the MSC to use for voice path establishment.
Intra MINS Call Connection After this, the ring back tone shall be played at the A-party MS, using RTP session through the port received in the “CM Service Request”.
Now the B-party Serving MSC shall send the “Alert with Information” message to the B-party Serving BSC, which shall make the handset of the B-party to start audible ringing.
When the B-party goes off-hook, the B-party serving BSC shall send a “Connect” message to the B-party serving MSC, indicating the same.
CALL TERMINATION
Intra MINS Call Termination
When any MS wants to terminate the call, the respective Serving BSC shall send the “Clear Request” message to its respective Serving MSC to indicate that it wishes to release all ServiceOption connections and the associated dedicated resource to that MS.
The “Clear Request” message shall contain the following parameters- Cause (OAM Intervention, Equipment failure, protocol error, radio interface failure, normal cause) and Cause Layer 3 (when the MS sends the “Release Order” to clear the call), which indicate the exact reason for sending this message
Intra MINS Call Termination
In response to “Clear Request”, “Clear Command” message shall be sent from serving MSC to serving BSC instructing it to release all service option connections to the MS and the associated dedicated resources. This message shall also contain the Cause and Cause Layer 3 parameters.
Then the serving BSC shall send “Clear Complete” message to the serving MSC to inform that all service option connections to the MS and the associated dedicated resource have been successfully cleared. The “Clear Complete” message shall have the Power Down indicator flag that indicates that the mobile powered down at the end of the call.
After that the “Clear Command” and “Clear Complete” message shall be exchanged to clear all the resources for the second party engaged in the call.
Feature Invocation
The “FEATREQ” (Feature Request) operation is used to request feature subscription on behalf of a registered MS. When performing digit analysis of the dialed digits received from the MS, the MSC shall detect that the dialed digits are a feature control access. After Validating tehA-party permissions, the Serving MSC shall send the feature code string (i.e. a string of digits including a feature code), received from the served MS to the HLR associated with the MS in the “FEATREQ” message. The HLR shall determine the appropriate feature treatment based on the received information and shall return this in a “featreq” response message. In this case, the response from the HLR shall not include instructions for the Serving System to set up the call.
Registration Cancellation:
The Registration Cancellation (“REGCANC”) operation is used to report, to the prior serving VLR or prior serving MSC, that a previously registered MS is no longer in its serving area. The scenarios identified for Registration Cancellation are: 1) MS de-registration by HLR due to Single Access. 2) MS de-registration by HLR due to Multiple Access –Successful scenario. 3) MS de-registration by HLR due to Multiple Access –Unsuccessful scenario 4) MS Deregistered by Serving MSC 5) MS Deregistered by Serving VLR 6) MS Deregistered by MINS (HLR) 7) MS Deregistered by RIM
Bulk Deregistration
The “BULKDEREG” (Bulk Deregistration) operation is used by a VLR to inform the HLR that all roaming MS data associated with the VLR has been removed.
The VLR shall send the “BULKDEREG” message to the HLR to inform the HLR that the VLR has removed all the roaming MS data associated with that HLR. The HLR shall acknowledge the receipt of this message by an empty “bulkdereg”.
Bulk Deregistration Call Flow
Unreliable Roamer Data Directive
The “UNRELDIR” (UnreliableRoamerDataDirective) operation is used by the HLR to inform its associated Serving System VLRs that it has experienced a failure, which has rendered its roaming MS data unreliable.
The VLR shall remove all record of the MS associated with the HLR from its memory and shall acknowledge the receipt of the same via an empty “unreldir”.
Unreliable Roamer Data Directive Call Flow
Qualification Directive
The “QUALDIR” (QualificationDirective) operation is used to update the authorization information, profile information, or both, previously obtained for an MS.
One of the several possible results is achieved: 1. The MS is re-authorized with an indication of the authorization duration. 2. The MS is re-authorized with an indication of the authorization duration along with the delivery of the MS’s updated calling capabilities to the serving system. 3. An update of the MS’s calling capabilities is delivered to the serving system. 4. The MS is de-authorized with reason (e.g., due to a delinquent account).
ADVANTAGES OF MINS:- ¬ All things are done on Internet Protocol (IP). That’s why it so fast, cheaper than other systems. ¬ Royalty on the Qualcomm chip was as below: • 5$ per subscriber in INDIA • 2$ per subscriber in CHINA • Nothing in U.S.A. But in the manufacture of the MINS system Qualcomm chip for BSC was not required so automatically cost is reduced. ¬ Compact size and can be install anywhere on a single table also. ¬ It more useful for the inter communication in between the remote areas in INDIA. ¬ After MINS launch, local calls in INDIA should be free only on the monthly rental. ¬ After MINS launch, ISD calls rate will be near about 2 Rs./min. ACHIEVEMENTS The knowledge we acquired from this training in depth about how a mobile makes a call and get connected to other mobile was something like having a plethora amount of knowledge in mobile network system. It is not only just a knowledge we gained through this training, but how to cope up with the environment, how to manage ourselves when there is no guardian with us to take care of us and to guide us and at most how to behave in office, in front of our seniors and with our team-mates. We were always treated as an employee there, never as a trainee, so it was also a plus point for us to have a experience of what we will really would able to get somewhere after completing our engineering degree. We had experienced just like that we are working in a multinational company for 45 days. It was incredible experience being there with those brilliant technies. CONCLUSIONS The 45 days summer practical training undertaken at Reliance Communication, Dhirubhai Ambani Knowledge City, Navi Mumbai was completed with a great enthusiasm and success. The main aim of having introduced to a totally new office environment and to learn stunning new things in life was covered in the training period. We came near to the life what we have to face in our coming life working 12 hrs a days, 6days a week and only 10-15days leave in whole year. We came to know that life is too fast and short; this is the only time when we can do something to make our career. It will worth to regret afterwards in life that we have not work hard when we have to. So we have to work hard now only. GLOSSARY • ITIC – internet technology information centre • DAKC-Dhirubhai ambani knowledge city • MINS- mobile integrated network system • MS- mobile system • BSC-Base station controller • BTS- Base transceiver system • MSC-mobile switching centre • HLR-home location register • VLR-visitor location register • CLR-common location register • MGC- Media Gateway Controller • SSD-Shared Secret Data • GSM-Global System for Mobile Communication • PSTN-Public Switched Telephone Network • OTAF-Over The Air functionality • VMS-voice mail system • LIS-legal interception system • ESN-Electronic serial number • MDN-mobile directory number • MAC-medium access control • MCSB-message control and status block • SIM-subscriber identity module • IMEI-International mobile equipment identity • IMSI-International mobile subscriber identity • COTS-commercial Off-the-shelf • RTOS-Real time operating system • CDMA-code division multiple access • CP-Call processing • TL-Transport layer • ECAM-Extended channel assignment message • ORM-origination message • CCR- call connection reference • CRBT- caller ring back tone • ACK-Acknowledgement • MCC-Mobile country code • MCSB-message control and status block • CDR-call data recorder • CLI-caller line identification • DSP-Digital signal processing • CCS-common channel signaling • UDP-user datagram protocol • OAM-operation administrator management • LAC-link access channel • MAC-Medium access channel • TCP-transmission control protocol CTR- channel transmitter reception
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|MS-MOBILE SYSTEM |
