GITBOOK-42: No subject

README.md

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-# 2G-GSM
+---
+description: >-
+  Dive into our comprehensive article discussing 2G - GSM technology, its
+  history, impact and evolution. Explore how the 2G network revolutionized
+  communication.
+cover: .gitbook/assets/blueprint_066cbb8c-1848-756f-8000-6d164331fc81.webp
+coverY: 0
+layout:
+  cover:
+    visible: true
+    size: hero
+  title:
+    visible: true
+  description:
+    visible: true
+  tableOfContents:
+    visible: true
+  outline:
+    visible: true
+  pagination:
+    visible: true
+---
+
+# Intro
+
+GSM (Global System for Mobile Communications) is a standard developed to describe protocols for second-generation (2G) digital cellular networks used by mobile phones.
+
+It became the default global standard for mobile communications, ensuring interoperability of mobile devices across different regions. 
+
+{% @mailchimp/mailchimpSubscribe %}
+
+
+
+GSM technology operates in various frequency bands, primarily 900/1800 MHz, and utilizes time division multiple access (TDMA) to divide each frequency channel into time slots. 
+
+This allows multiple users to share the same bandwidth efficiently. GSM supports voice calls, SMS, and limited data services, forming the backbone of modern mobile communication systems.
+
+{% embed url="https://cli-ck.me/rfs" %}
+
+{% embed url="https://cli-ck.me/hostinger" %}
+
+{% embed url="https://cli-ck.me/visual-cv" %}

SUMMARY.md

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+# Table of contents
+
+* [Intro](README.md)
+* [Standards](standards/README.md)
+  * [Timeline](standards/timeline.md)
+  * [PCM30](standards/pcm30.md)
+  * [PCM24](standards/pcm24.md)
+
+## Architecture
+
+* [✅ GSM Radio Stack](architecture/gsm-radio-stack/README.md)
+  * [Layer 1 - Radio](architecture/gsm-radio-stack/layer-1-radio.md)
+  * [Layer 2 - LAP-Dm](architecture/gsm-radio-stack/layer-2-lap-dm.md)
+  * [Layer 3 − GSM signalling](architecture/gsm-radio-stack/layer-3-gsm-signalling.md)
+* [MS - Mobile Station](architecture/ms-mobile-station/README.md)
+  * [ME - Mobile Equipment](architecture/ms-mobile-station/me-mobile-equipment/README.md)
+    * [Baseband](architecture/ms-mobile-station/me-mobile-equipment/baseband.md)
+  * [SIM Card - Subscriber Identity Module](architecture/ms-mobile-station/sim-card-subscriber-identity-module.md)
+* [BSS - Base Station Subsystem](architecture/bss-base-station-subsystem/README.md)
+  * [🟢 BTS - Base Transceiver Station](architecture/bss-base-station-subsystem/bts-base-transceiver-station.md)
+  * [✅ BSC - Base Station Controller](architecture/bss-base-station-subsystem/bsc-base-station-controller.md)
+* [NSS - Network Switching Subsystem](architecture/nss-network-switching-subsystem/README.md)
+  * [MSC - Mobile Switching Center](architecture/nss-network-switching-subsystem/msc-mobile-switching-center.md)
+  * [HLR - Home Location Register](architecture/nss-network-switching-subsystem/hlr-home-location-register.md)
+  * [VLR - Visitor Location Register](architecture/nss-network-switching-subsystem/vlr-visitor-location-register.md)
+  * [AuC - Authentication Center](architecture/nss-network-switching-subsystem/auc-authentication-center.md)
+  * [EIR - Equipment Identity Register](architecture/nss-network-switching-subsystem/eir-equipment-identity-register.md)
+  * [VMS - Voice Mail Subsystem](architecture/nss-network-switching-subsystem/vms-voice-mail-subsystem.md)
+  * [IWF - Interworking Function](architecture/nss-network-switching-subsystem/iwf-interworking-function.md)
+* [OSS - Operation Support Subsystem](architecture/oss-operation-support-subsystem/README.md)
+  * [OMC - Operation and Maintence Center](architecture/oss-operation-support-subsystem/omc-operation-and-maintence-center.md)
+  * [NMC - Network Managment Center](architecture/oss-operation-support-subsystem/nmc-network-managment-center.md)
+* [ABC - Administration & Billing Center](architecture/abc-administration-and-billing-center.md)
+
+## GSM Channels
+
+* [Intro](gsm-channels/intro.md)
+* [Traffic Channels](gsm-channels/traffic-channels/README.md)
+  * [TCH/F](gsm-channels/traffic-channels/tch-f.md)
+  * [TCH/H](gsm-channels/traffic-channels/tch-h.md)
+* [Signalling Channels](gsm-channels/signalling-channels/README.md)
+  * [Broadcast Channels](gsm-channels/signalling-channels/broadcast-channels/README.md)
+    * [FCCH - Frequency Correction Channel](gsm-channels/signalling-channels/broadcast-channels/fcch-frequency-correction-channel.md)
+    * [✅ SCH - Synchronization Channel](gsm-channels/signalling-channels/broadcast-channels/sch-synchronization-channel.md)
+    * [✅ BCCH - Broadcast Control Channel](gsm-channels/signalling-channels/broadcast-channels/bcch-broadcast-control-channel.md)
+    * [✅ CBCH - Cell Broadcast Channel](gsm-channels/signalling-channels/broadcast-channels/cbch-cell-broadcast-channel.md)
+  * [Common Control Channels](gsm-channels/signalling-channels/common-control-channels/README.md)
+    * [Point-to-Multipoint Channels](gsm-channels/signalling-channels/common-control-channels/point-to-multipoint-channels/README.md)
+      * [PCH - Paging Channel](gsm-channels/signalling-channels/common-control-channels/point-to-multipoint-channels/pch-paging-channel.md)
+      * [RACH - Random Access Channel](gsm-channels/signalling-channels/common-control-channels/point-to-multipoint-channels/rach-random-access-channel.md)
+      * [AGCH - Access Grant Channel](gsm-channels/signalling-channels/common-control-channels/point-to-multipoint-channels/agch-access-grant-channel.md)
+  * [Dedicated Channels](gsm-channels/signalling-channels/dedicated-channels/README.md)
+    * [✅ Point-To-Point Signalling](gsm-channels/signalling-channels/dedicated-channels/point-to-point-signalling/README.md)
+      * [✅ SDCCH - Stand-alone Dedicated Control Channel](gsm-channels/signalling-channels/dedicated-channels/point-to-point-signalling/sdcch-stand-alone-dedicated-control-channel.md)
+      * [✅ SACCH - Slow Associated Control Channel](gsm-channels/signalling-channels/dedicated-channels/point-to-point-signalling/sacch-slow-associated-control-channel.md)
+      * [✅ FACCH - Fast Associated Control Channel](gsm-channels/signalling-channels/dedicated-channels/point-to-point-signalling/facch-fast-associated-control-channel.md)
+
+## GSM Interfaces
+
+* [✅ A interface](gsm-interfaces/a-interface.md)
+* [✅ A-ter interface](gsm-interfaces/a-ter-interface.md)
+* [✅ A-bis interface](gsm-interfaces/a-bis-interface.md)
+* [✅ Um interface](gsm-interfaces/um-interface.md)
+
+## PLMN - Public Land Mobile Network
+
+* [Cell Id](plmn-public-land-mobile-network/cell-id.md)
+* [LAI - Location Area Identification](plmn-public-land-mobile-network/lai-location-area-identification.md)
+* [ARFCNs](plmn-public-land-mobile-network/arfcns.md)
+
+## System Information Messages
+
+* [✅ System information-1(SI1)](system-information-messages/system-information-1-si1.md)
+* [✅ System information-2(SI2)](system-information-messages/system-information-2-si2.md)
+* [System information-2bis(SI-2bis)](system-information-messages/system-information-2bis-si-2bis.md)
+* [System information-2ter(SI-2ter)](system-information-messages/system-information-2ter-si-2ter.md)
+* [System information-2 Quarter (SI-2Quater)](system-information-messages/system-information-2-quarter-si-2quater.md)
+* [✅ System information-3 (SI3)](system-information-messages/system-information-3-si3.md)
+* [System information-4 (SI4)](system-information-messages/system-information-4-si4.md)
+* [System information-5 (SI5)](system-information-messages/system-information-5-si5.md)
+* [System information-6 (SI6)](system-information-messages/system-information-6-si6.md)
+* [System information-7 (SI7)](system-information-messages/system-information-7-si7.md)
+* [System information-8 (SI8)](system-information-messages/system-information-8-si8.md)
+* [System information-9 (SI9)](system-information-messages/system-information-9-si9.md)
+* [System information-13 (SI13)](system-information-messages/system-information-13-si13.md)
+
+## Docs
+
+* [Page 2](docs/page-2.md)
+
+## Paging Requests
+
+* [Paging request type 1](paging-requests/paging-request-type-1.md)
+* [Paging request type 2](paging-requests/paging-request-type-2.md)
+
+## Messages for Mobility Management
+
+* [Intro](messages-for-mobility-management/intro.md)
+* [✅ Registration messages](messages-for-mobility-management/registration-messages/README.md)
+  * [IMSI DETACH INDICATION](messages-for-mobility-management/registration-messages/imsi-detach-indication.md)
+  * [LOCATION UPDATING ACCEPT](messages-for-mobility-management/registration-messages/location-updating-accept.md)
+  * [LOCATION UPDATING REJECT](messages-for-mobility-management/registration-messages/location-updating-reject.md)
+  * [LOCATION UPDATING REQUEST](messages-for-mobility-management/registration-messages/location-updating-request.md)
+* [Security messages](messages-for-mobility-management/security-messages.md)
+* [Connection management messages](messages-for-mobility-management/connection-management-messages.md)
+* [Miscellaneous message](messages-for-mobility-management/miscellaneous-message.md)

architecture/abc-administration-and-billing-center.md

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+# ABC - Administration & Billing Center
+
+ABC is responsible to provisioning SIM cards and insert the customer data inside HLR and equipment data inside AuC.
+
+Manage CDR - Call Records

architecture/bss-base-station-subsystem/README.md

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+# BSS - Base Station Subsystem
+

architecture/bss-base-station-subsystem/bsc-base-station-controller.md

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+# ✅ BSC - Base Station Controller
+
+### BSC Functions
+
+1. Manages BTSs
+2. Manage Radio Resources
+3. Monitor and Control Inter BTS handhovers
+4. Connct to MSC to make calls
+
+### Huawei BSC6900
+
+![](<../../.gitbook/assets/Huawei BSC6900.webp>)
+
+{% file src="../../.gitbook/assets/Huawei BSC6900.pdf" %}
+
+### BSC - Base Station Controller
+
+A Base Station Controller (BSC) is a critical component in a cellular network, responsible for managing multiple Base Transceiver Stations (BTS).&#x20;
+
+It handles radio resource management, inter-BTS handovers, and connecting BTSs to the Mobile Switching Center (MSC) to facilitate call processing and mobility management.&#x20;
+
+The BSC optimizes the network's performance and ensures seamless communication between mobile users.

architecture/bss-base-station-subsystem/bts-base-transceiver-station.md

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+# 🟢 BTS - Base Transceiver Station
+
+### Type of Channels
+
+1. Common Control Channels
+2. Dedicated Channels
+
+### Base Transceiver Station
+
+A Base Transceiver Station (BTS) is a key component in the GSM architecture. It consists of:
+
+* **Transmitters and Receivers:** Handle communication with mobile phones via radio waves.
+* **Antennas:** Emit and receive signals within a specific coverage area.
+* **Signal Processing Units:** Manage the encoding, decoding, and encryption of signals.
+
+The BTS interfaces with the Mobile Station (MS) and the Base Station Controller (BSC). Responsible for managing radio resources, it facilitates user connectivity and communication services in a cellular network.
+
+### Transmitters and Receivers
+
+Transmitters and Receivers are critical components of a BTS. The **transmitters** generate and send radio signals to the Mobile Station (MS), enabling communication. The **receivers**, on the other hand, capture incoming signals from the MS. Together, they facilitate two-way communication by converting data between radio waves and electrical signals within the GSM network.
+
+### Antennas
+
+Antennas are integral parts of a BTS, responsible for transmitting and receiving radio waves to and from mobile stations within a designated coverage area. They convert electrical signals into radio waves for transmission and vice versa for reception. The design and placement of antennas determine the coverage and capacity of the network, ensuring that signals are effectively propagated and received. Different types of antennas, including omnidirectional and directional, are used based on the network requirements and geographical constraints.
+
+### Signal Processing Units
+
+Signal Processing Units (SPUs) are vital components in a BTS that handle various tasks associated with digital signal processing. These units perform operations such as modulation, encoding, and error correction to ensure the integrity and clarity of communication signals. By converting analog signals to digital formats and vice versa, SPUs play a critical role in maintaining the quality and reliability of data transmission within the GSM network.

architecture/gsm-radio-stack/README.md

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+# ✅ GSM Radio Stack
+
+![Intro GSM Stack
+](../../.gitbook/assets/slide\_11.jpg)
+
+## MS to BTS Protocols
+
+Based on the interface, the GSM signaling protocol is assembled into three general layers −
+
+* **Layer 1** − The physical layer. It uses the channel structures over the air interface.
+* [**Layer 2**](../../gsm-interfaces/um-interface.md) − The data-link layer. Across the Um interface, the data-link layer is a modified version of the Link access protocol for the D channel (LAP-D) protocol used in ISDN, called Link access protocol on the Dm channel (LAP-Dm). Across the A interface, the Message Transfer Part (MTP), Layer 2 of SS7 is used.
+* **Layer 3** − GSM signalling protocol’s third layer is divided into three sublayers −
+  * Radio Resource Management (RR),
+  * Mobility Management (MM), and
+  * Connection Management (CM).
+
+
+
+{% embed url="https://cli-ck.me/ine-security" %}
+
+{% embed url="https://cli-ck.me/visual-cv" %}

architecture/gsm-radio-stack/layer-1-radio.md

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+# Layer 1 - Radio
+
+## GSM Layer 1 - Radio
+
+GSM Layer 1, also known as the Physical Layer, handles the radio transmission and reception. 
+
+It deals with modulation, demodulation, frequency hopping, and time-division multiple access (TDMA). 
+
+This layer ensures the correct transmission of data between the mobile station and the network.
+
+In GSM, the Time Division Multiplexing (TDM) technique is used to allocate specific time slots to multiple users on the same frequency channel. 
+
+Each user transmits in rapid succession, one after the other, each using their allocated time slot.
+
+This method enables multiple mobile stations to share the same frequency channel without interference, maximizing the efficiency of available bandwidth.

architecture/gsm-radio-stack/layer-2-lap-dm.md

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+# Layer 2 - LAP-Dm
+
+#### GSM Layer 2 - LAP-Dm
+
+GSM Layer 2, or the Link Access Protocol for the Dm channel (LAP-Dm), manages the data link control in GSM networks. LAP-Dm is responsible for:
+
+* Establishing a reliable communication link between Mobile Stations (MS) and the Base Transceiver Station (BTS).
+* Handling error correction, flow control, and frame synchronization.
+* Ensuring data integrity through frame acknowledgment and retransmission of corrupted frames.

architecture/gsm-radio-stack/layer-3-gsm-signalling.md

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+# Layer 3 − GSM signalling
+
+### CM - Connection Management Layer
+
+The CM layer is the topmost layer of the GSM protocol stack. 
+
+This layer is responsible for Call Control, Supplementary Service Management, and Short Message Service Management. 
+
+Each of these services are treated as individual layer within the CM layer. 
+
+Other functions of the CC sublayer include call establishment, selection of the type of service (including alternating between services during a call), and call release.
+
+Read More about it on `Paging Requests Messages`
+
+### MM - Mobility Management Layer
+
+The MM layer is stacked above the RR layer. It handles the functions that arise from the mobility of the subscriber, as well as the authentication and security aspects. 
+
+Location management is concerned with the procedures that enable the system to know the current location of a powered-on MS so that incoming call routing can be completed.
+
+### RR - Radio Resource Management Layer 
+
+The RR layer is the lower layer that manages a link, both radio and fixed, between the MS and the MSC. For this formation, the main components involved are the MS, BSS, and MSC. 
+
+The responsibility of the RR layer is to manage the RR-session, the time when a mobile is in a dedicated mode, and the radio channels including the allocation of dedicated channels.

architecture/ms-mobile-station/README.md

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+# MS - Mobile Station
+
+**MS - Mobile Station**
+
+A Mobile Station (MS) refers to a wireless device used for communication in cellular networks.
+
+It comprises both the mobile equipment (ME), such as a smartphone, and the subscriber identity module (SIM), which stores user-related information and authentication data. 
+
+The MS allows users to make calls, send texts, and access mobile data services.

architecture/ms-mobile-station/me-mobile-equipment/README.md

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+# ME - Mobile Equipment
+
+### ME - Mobile Equipment
+
+Mobile Equipment (ME) refers to the physical hardware of a mobile device. This includes components like the phone casing, battery, screen, and internal electronics that facilitate communication and functionality of the device. 
+
+The ME is identified by a unique IMEI number.
+
+### IMEI - International Mobile Equipment Identity
+
+The International Mobile Equipment Identity (IMEI) is a unique 15-digit number used to identify mobile devices. 
+
+It helps in differentiating each device on a mobile network and can be used for tracking or blocking a lost or stolen device. 
+
+The IMEI is typically found printed inside the battery compartment of the device, and can also be displayed on the screen by dialing \*#06#.

architecture/ms-mobile-station/me-mobile-equipment/baseband.md

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+# Baseband
+

architecture/ms-mobile-station/sim-card-subscriber-identity-module.md

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+# SIM Card - Subscriber Identity Module
+
+## MSISDN
+
+Is stored on HLR from operator.
+
+### Decoding MSISDN
+
+<mark style="color:red;">**00 351**</mark> <mark style="color:orange;">91</mark> <mark style="color:green;">000</mark> <mark style="color:purple;">11</mark> <mark style="color:blue;">22</mark>
+
+### Prefixes
+
+National = 0
+
+Internacional = +351 or <mark style="color:red;">00351</mark> (Portugal)
+
+### MCC - Mobile Country Code
+
+<mark style="color:orange;">91 - Vodafone Portugal</mark>
+
+### NDC - Network Destination Code
+
+<mark style="color:green;">000</mark>
+
+**Explanation**:
+
+The section above provides important codes and identifiers related to your mobile network and SIM card.
+
+* **Internacional**: The international dialing code for Portugal.
+* **MCC**: Mobile Country Code, specific to Vodafone Portugal.
+* **NDC**: Network Destination Code, often used in conjunction with MCC for routing.
+* **ICCID**: Identifies the SIM card uniquely.
+* **PIN**: Protects your SIM from unauthorized use.
+* **PUK**: Unblocks your SIM if the PIN is entered incorrectly multiple times.
+* **PIN2**: An additional security code for advanced features.
+
+
+
+**ICCID**: The Integrated Circuit Card Identifier is a unique number assigned to your SIM card.
+
+**PIN**: A Personal Identification Number is a security code that protects against unauthorized use of your SIM card.
+
+**PUK**: A PIN Unblocking Key is used to unblock your SIM card if the PIN is entered incorrectly multiple times.
+
+**PIN2**: Similar to the PIN, this is another security code used to access advanced SIM features.
+
+**PUK2**: This is the key used to unblock the PIN2 if it is entered incorrectly multiple times.

architecture/nss-network-switching-subsystem/README.md

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+# NSS - Network Switching Subsystem
+
+#### Network Switching Subsystem (NSS)
+
+The Network Switching Subsystem (NSS) is a key component in a GSM network responsible for call processing and subscriber mobility management. It consists of several network elements, including:
+
+* **Mobile Switching Center (MSC):** Manages call setup, routing, and mobility.
+* **Home Location Register (HLR):** A database storing details of each subscriber.
+* **Visitor Location Register (VLR):** Temporarily holds data about subscribers currently in the MSC area.
+* **Authentication Center (AUC):** Provides data for verifying user identity.
+* **Equipment Identity Register (EIR):** Keeps records of mobile equipment to prevent fraud.
+
+The NSS facilitates communication between mobile users and connects them to other networks.

architecture/nss-network-switching-subsystem/auc-authentication-center.md

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+# AuC - Authentication Center
+

architecture/nss-network-switching-subsystem/eir-equipment-identity-register.md

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+# EIR - Equipment Identity Register
+