Mobile Radio Channel Bring-Up and Link Adaptation for Packet Data Services in Conjunction with Higher Level Connection Management such as TCP / IP
Original Publication Date: 2003-Sep-25
Included in the Prior Art Database: 2003-Sep-25
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In mobile networks, e.g. Global System for Mobile communications (GSM) or Universal Mobile Telecommunication System (UMTS), a physical channel can be configured for circuit switched or packet switched traffic. The following description is based on the GSM system, but the invention step can also be applied to other technologies, e.g. to UMTS or TD-SCDMA (Time Division Synchronous Code Division Multiple Access). Only packet switched data shall be covered by this invention. After setting up the connection between the Packet Control Unit (PCU) and the Base Transceiver System (BTS) and after configuring the air interface channel, data can be transmitted between the BTS and the Mobile Station (MS). For the General Packet Radio Service (GPRS) and the Enhanced-GPRS (E-GPRS) the user information is conveyed in packets. For transmission on the air interface (Um), different coding schemes can be applied depending on the radio conditions. In poor radio conditions, a more robust coding scheme is necessary to improve the transmission quality. Channel coding introduces redundancy into the data packets for detecting and correcting transmission errors. GPRS offers four different coding schemes (CS-1 to CS-4), E-GPRS has nine (MCS-1 to MCS-9), each of them offering a different level of protection. The gross data volume of the transmission on the air interface consists of payload (user information) and coding. A more robust coding scheme (e.g. CS-2) includes a higher amount of coding bits and less payload than a less robust coding scheme (e.g. CS-3). For maximization of the throughput, more robust coding schemes are used when the radio link quality is poor, whereas less robust coding schemes or even uncoded schemes (CS-4 and MCS-9) are applied for good radio conditions. In most cases, an Initial Coding Scheme (ICS) is defined, and the data transmission starts with this predefined coding scheme.