Beyond 3G Mobile Radio Systems (Joint)
At the Research Group for Radio Communications a system concept termed JOINT (Joint Transmission and Detection Integrated Network) for beyond 3G mobile radio systems is being developed. JOINT applies adaptive antenna techniques as well as the joint transmission (JT) and joint detection (JD) techniques. The main goals are to increase capacity compared to 3G cellular systems and WLAN systems as for instance IEEE 802.11, and to keep the complexity of the mobile terminals at a low level. In the following, important characteristics of JOINT are listed:
- The entire area intended for mobile radio services is subdivided into service areas (SA). The SAs can be adjacent to each other or isolated. One SA can represent a building, a floor of a building or even a part of an inner city. Thus, a SA corresponds to a number of cells of a common pico- or micro-cellular system. Since the above mentioned JD and JT techniques can eliminate the interference within a SA, the advantage of cancelling intercell interference is obtained by the introduction of the SA instead of cells.
- Within each SA numerous mobile terminals (MT) can be active.
- On the fixed network side multiple access points (APs) per SA, which are connected to a central unit (CU), will be used. The central unit is connected to the core network.
- Each AP and each MT applies an antenna consisting of a single antenna element or an array of antenna elements.
- The communication of a MT with the CU occurs over several APs simultaneously.
- The MTs are kept simple, and the necessary processing efforts are concentrated in the CU.
- Multicarrier transmission using orthogonal carriers will be applied. The option of combining the multicarrier transmission with the multiple access schemes TDMA, FDMA and CDMA is given.
- TDD is the duplexing scheme in favor.
- In the uplink JD is used. This means that the received signals at the antennas of the APs are jointly processed in the CU. The goal is to eliminate multiple access interference (MAI) originating inside the SAs.
- In the downlink JT is used. The antennas of the APs transmit signals, which are structured in such a way that each MTs of a SA obtains the corresponding signal practically free from any MAI by applying a simple receiver structure.
- For channel estimation the scheme joint channel estimation (JCE) is proposed.