NETWORK CONTROLLED CHANNEL
BACKGROUND OF THE INVENTION
The present invention generally relates to wireless communication systems, and particularly relates to the reporting of channel information in a wireless communication system.
Channel information (e.g., signal to noise ratio on a par- 10 ticular channel or channel impulse response) helps characterize or otherwise describe a channel between a base station and a mobile terminal in a wireless communication system. If the fixed portion of the wireless communication system has knowledge of the channel characteristics, then the system can 15 make adjustments to improve service. Indeed, the reporting of channel information from many mobile terminals back to base stations generally improves the system-wide performance of wireless communication systems. Further, the emerging multiple transmit antenna/multiple receive antenna 20 systems see some of the most improvement from channel information feedback. It should be noted, however, that the theoretical amount and complexity of channel information that can be fed back increases as the number of transmit and receive antennas increases. Further, because of the time-varying fading environments encountered by mobile terminals, the feedback of channel information from the mobile terminals to the base stations should be timely.
In one embodiment, the present invention provides a method of reporting channel information in a wireless communication system, the method comprising a mobile terminal 35 normally providing a basic channel report to the relatively fixed portion of the wireless communication system (e.g., to a base station), the basic channel report at least partially characterizing a downlink channel; the mobile terminal receiving at least one common feedback criterion broadcast to 40 a plurality of mobile terminals; the mobile terminal determining if the mobile terminal satisfies a condition based on the at least one common feedback criterion; and the mobile terminal selectively providing an enhanced channel report regarding the downlink channel to the wireless communication 45 system based on the determining. The basic channel report may comprise information related to a first set of one or more channel parameters of the downlink channel, and the enhanced channel report may provide greater detail on the first set of channel parameters than the basic channel report 50 and/or the enhanced channel report may provide information related to a second set of one or more channel parameters of the downlink channel. In addition, the enhanced channel report may be a superset of the basic channel report.
In another embodiment, the present invention provides a 55 method of controlling channel information reporting in a wireless communication system, the method comprising: a base station receiving a plurality of basic channel reports transmitted from a plurality of mobile terminals, the basic channel reports at least partially characterizing a downlink 60 channel from the base station; determining, by the base station, at least one common feedback criterion based on a desired amount of enhanced channel reports; the at least one common feedback criterion helping to define a condition whose satisfaction controls which plurality of the plurality of 65 mobile terminals subsequently transmit an enhanced channel report regarding the downlink channel to the base station; and
broadcast transmitting the at least one common feedback criterion from the base station to the plurality of mobile terminals.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a wireless communication network that may operate according to one or more embodiments of the present invention.
FIG. 2 shows a flowchart of one method of reporting channel information according to one or more embodiments of the present invention.
FIG. 3 shows one message arrangement that may be used by a mobile terminal to transmit channel reports.
FIG. 4 shows an alternate message arrangement that may be used by a mobile terminal to transmit channel reports.
FIG. 5 shows still another message arrangement that may be used by a mobile terminal to transmit channel reports.
FIG. 6 shows one possible embodiment of a mobile terminal that may operate according to one or more embodiments of the present invention.
FIG. 7 shows a flowchart of a method of reporting channel information according to one or more embodiments of the present invention.
FIG. 8 shows one possible embodiment of a base station that may operate according to one or more embodiments of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 illustrates an exemplary wireless communication network 10, which may be configured as a WCDMA/Release 5 network. For reference, the WCDMA Release 5 standard is discussed in "Evolving WCDMA for Improved High Speed Mobile Internet," S. Parkvall, J. Peisa, A. Furuskar, M. Samuelsson, and M. Persson, in Proc. Future Telecommunications Conference, Beijing, China, Nov. 28-30,2001, which is incorporated herein by reference. In general, network 10 typically includes a core network 11 and a radio network. The radio network typically comprises a Radio Network Controller (RNC) 12 coupled to a plurality of base stations 14 (sometimes referred to as "nodeB's"). The RNC 12 may bethought of generally serving the function of the more commonly known Base Station Controllers (BSC) found in many existing wireless communication networks, such as GSM or IS-136 systems. The RNC 12 serves as a connection between the core network 11 and the base stations 14. The RNC 12 communicates with various external networks such as the Public Switched Telephone Network (PSTN) 104 and one or more Public Data Networks (PDNs, e.g., the Internet) 106 through the core network 11. Mobile terminals 30 communicate to the base stations 14 via the "air interface" as defined by the appropriate network standards. Those skilled in the art will appreciate that other network architectures may be used, and that network 10 may include more or different entities as needed or desired. In general, detailed knowledge of the operational functions of the wireless communication network 10 is not necessary for understanding the present invention, and such details are not discussed further herein as they are considered to be understood by those of ordinary skill in the art.
As shown in FIG. 1, each base station 14 is typically in direct communication with a plurality of mobile terminals 3 0. While a maximum of three mobile terminals 30 are shown in communication with a given base station 14 in FIG. 1, it should be understood that any number of mobile terminals 30 may be in direct communication with a given base station 14.