This article describes the “local breakout” function in YateBTS/OpenBTS GPRS cells, where user IP traffic originates directly from the cell site instead of from a centralized GGSN in the core network. Standard GPRS Architecture The standard GPRS data network has these parts: BTS – the actual radio basestation, which handles user traffic up to layer …
The purpose of this article is to provide some background for network managers about the kinds of radio hardware diagnostics that are available from typical radio basestations (GSM BTS, UMTS NodeB, LTE eNodeB, 5G-NR gNodeB, etc.). They probably will not see these diagnostics directly, only the resulting warnings and alarms, but it takes some of …
This article is about protocols used or proposed for connecting remote radio heads (RRH) or radio units (RU) or whatever you call that part of the network to baseband units (BBU) or data units (DU) or C-RAN, or whatever you have in that other part of the network: RRH/RU/whatever <-> BBU/DU/C-RAN/whatever The fact that the …
This post describes the operation of the MTC Physical Downlink Control Channel (MPDCCH) for sending downlink assignments and uplink grants to the client device. Purpose of the MPDCCH In LTE-M, radio resources assignments (the times and frequencies when a device is expected to receive or transmit) are dynamic, for both downlink (“DL”, network to device) …
Introduction NiPC (“network in a PC”) is a mode of operation supported by YateBTS that allows the basestation to operate in 2.5G GSM/GPRS mode without a core network. While YateBTS NiPC mode does support normal authentication and ciphering with a local SIM database, NiPC also offers a feature that bypasses all security procedures and allows …
Introduction Cell broadcast (CB) is a way to deliver a text message to large numbers of handsets over the cellular network. Its main use today is the delivery of Public Warning System (PWS) messages, also called CMAS, ETWS, Presidential Alerts, EU-Alerts, or other names in different parts of the world. The Legba Lab Kit supports …
Introduction Many 4G networks cannot carry plain old telephone calls, so many mobile operators support voice calls by transferring the handset to a 2G or 3G network for the duration of the call. The procedure for doing this is called “Circuit-Switched Fallback”, or CSFB. CSFB is an interesting procedure from a network operation perspective and …
