I. Carrier wireless resource control Equipment (RRC)

  • Background: Unlike PCS, mobile devices need to balance power consumption and transmission efficiency, and wireless modules can consume a lot of power if they are always on

  • Solution: The mobile device is in hibernation state by default. The mobile device must first contact the carrier’s wireless Resource Control Device (RRC) to allocate resources (or wait for the RRC notification) to send and receive data. The RRC is responsible for specifying:

    • Transmission time
    • Transmitted power: in sleep mode15mW, when active,1000mWto3500mW

2. End-to-end mobile operator network structure

The carrier network consists of the following two parts:

  • Wireless Access Network (RAN)

    • RRCThe equipment is arranged on the base station (as shown in the picture)eNodeB)

  • Core Network (CN)

    The core network mainly consists of the following parts:

    • PGW(Packet Gateway) : Public network egress/ingo of the carrier network, which is responsible for device allocationIPAddresses and the execution of related policies, such as packet filtering and checking, QoS Settings, and DoS defense
      • PCRF(Policy and Charging Rules Function ) : This module assistsPGWImplement relevant policies
    • SGW(Serving Gateway) :PGWAfter receiving downlink information,SGWResponsible for forwarding the packet to the user
      • MME(Mobility Management Entity) : Maintain all information related to users, including mobile phone location, tariff status, etc

Data packet transmission path

1. Uplink data

  1. The phone asks the base station to establish a wireless connection
  2. The phone transmits data to the base station at a specific speed and power
  3. Data is sent from the base station to the core network (viaSGWtoPGW)
  4. Data is sent from the core network to the public network

  • Delay in data transmission during uplink

    • At first connection, RRC handshake and state transition will be performed.

      • fromdormancytoactive < 100ms
      • fromPut on holdtoactive < 50ms

    • User-plane latency between mobile phones and base stations

    • Core route delay

    • Public Network Routing Delay

The basic data uplink process is as follows:

2. Downstream data

  1. After the data arrives on the carrier’s network, thePGWSent to theSGW.SGW 向 MMEA query
  2. If the phone is asleep,MMEIt is not known to which base station it is connected to, and it is sent to all base stations within its coverage areapagingThe message
  3. All base stations broadcast thispagingMessage allowing the device to re-establish a wireless connection to the base station
  4. The device also receives data periodically in the sleep statepagingMessage, found himself inpagingList, initiates a handshake message to re-establish a wireless connection to a nearby base station
  5. After the wireless connection with the base station is established, the base station givesMMESend a message informing them of the user’s location,MMEForward this information toSGW
  6. SGWSends downlink data to the base station
  7. The base station sends the data to the phone
  • After the mobile phone is connected, its corresponding base station andSGWA direct connection channel will be established between them, and the subsequent downlink data will be directly sent to the base station, without any needpagingMessage overhead (steps 2-5).

The basic flow of data downlink is shown as follows:

The resources

  • HPBN. Co/mobile – netw…

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