# 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. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://gsm.learn-telecom.com/architecture/gsm-radio-stack/layer-1-radio.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.