CN110663279B

CN110663279B - Broadcast feedback mechanism

Info

Publication number: CN110663279B
Application number: CN201780090960.3A
Authority: CN
Inventors: 贺海港; 郝鹏; 毕峰; 刘星; 肖华华
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2017-05-16
Filing date: 2017-05-16
Publication date: 2023-05-30
Anticipated expiration: 2037-05-16
Also published as: CN110663279A; WO2018209552A1

Abstract

Techniques, systems, and devices are disclosed that provide a feedback mechanism for wireless transmissions, particularly for broadcast transmissions. In one exemplary aspect, a method of wireless communication is disclosed. The method comprises the following steps: transmitting a reference signal to a mobile station before broadcasting system information; receiving feedback information from the mobile station in response to the reference signal; transmitting parameters for broadcasting system information to the mobile station based on the feedback information; and broadcasting the system information using the parameters.

Description

Broadcast feedback mechanism

Technical Field

This patent document relates generally to wireless communications.

Background

Mobile communication technology is moving the world towards increasingly connected and networked society. Next generation systems and wireless communication technologies will need to support a wider range of use case characteristics and provide a more complex range of access requirements and flexibility than existing wireless networks.

Disclosure of Invention

This patent document relates to techniques, systems and devices for providing a feedback mechanism for wireless transmissions, in particular for broadcast transmissions.

In one exemplary aspect, a method of wireless communication is disclosed. The method comprises the following steps: transmitting a reference signal to a mobile station before broadcasting system information; receiving feedback information from the mobile station in response to the reference signal; transmitting parameters for broadcasting system information to the mobile station based on the feedback information; and broadcasting the system information using the parameters.

In another exemplary aspect, a method of wireless communication is disclosed. The method comprises the following steps: receiving a reference signal from a base station in a broadcast channel; transmitting feedback information based on measurements responsive to the reference signal to the base station; receiving parameters for broadcasting system information from the base station, wherein the parameters are determined by the feedback information; and receiving a broadcast of the system information from the base station using the parameter.

In another exemplary aspect, a wireless communication device is disclosed. The apparatus comprises: a memory for storing codes; and a processor in communication with the memory and operable to execute the code to cause the wireless communication device to: transmitting a reference signal to a mobile station before broadcasting system information; receiving feedback information from the mobile station in response to the reference signal; transmitting parameters for broadcasting system information to the mobile station based on the feedback information; and broadcasting the system information using the parameters.

In yet another exemplary aspect, a wireless communication device is disclosed. The apparatus comprises: a memory for storing codes; and a processor in communication with the memory and operable to execute the code to cause the wireless communication device to: receiving a reference signal from a base station in a broadcast channel; transmitting feedback information based on measurements responsive to the reference signal to the base station; receiving parameters for broadcasting system information from the base station, wherein the parameters are determined by the feedback information; and receiving a broadcast of the system information from the base station using the parameter.

The above and other aspects and implementations thereof are described in more detail in the accompanying drawings, description and claims.

Drawings

Fig. 1 is a flow chart representation of an exemplary process for a feedback mechanism between a base station and a mobile station.

Fig. 2 is a flow chart representation of a wireless communication method implemented at a base station.

Fig. 3 is an exemplary mapping of groups of sequences with certain system information and feedback types, referred to as other system information (other SI).

Fig. 4A illustrates an exemplary pattern for demodulation reference signals (DMRS), which includes one Physical Downlink Shared Channel (PDSCH) symbol with a DMRS.

Fig. 4B illustrates an exemplary DMRS pattern including two PDSCH symbols with DMRS.

Fig. 4C illustrates an exemplary DMRS pattern including four PDSCH symbols with DMRS.

Fig. 5 shows a flow chart representation of a wireless communication method implemented at a mobile station.

Fig. 6A shows an exemplary diagram of a sequence that a mobile station transmits in its request for other SIs.

Fig. 6B shows an exemplary schematic of two sequences that a mobile station transmits in its request for other SIs.

Fig. 7 illustrates an example of a wireless communication system in which techniques according to one or more embodiments of the present technology may be applied.

Fig. 8 is a block diagram representation of a portion of a radio station.

Detailed Description

The rapid growth of mobile communications and advances in technology require greater capacity and higher data rates. Other things, energy consumption, equipment cost, spectrum resource allocation and latency are also important to the success of future networks.

Conventional wireless communications typically do not use a feedback mechanism for the broadcast channel of the transmission. Because the broadcast information transmitted by the base station is sent to a plurality of mobile stations, which are typically relatively large and geographically dispersed, it is necessary to ensure signal quality at all receiving mobile stations of the broadcast channel signal. Thus, typically, the base station uses relatively conservative broadcast channel parameters, such as low-order debugging and lower coding rates. The introduction of a feedback mechanism in such broadcast communications does not substantially improve the transmission efficiency of the broadcast information. In addition, if a feedback mechanism for the broadcast channel is introduced, it is generally desirable that all receiving mobile stations, or at least a large number of them, measure the channel quality and provide feedback for the broadcast channel to the base station. This will result in a reduced amount of available time-frequency resources for the feedback channel, thereby affecting other types of transmissions.

New generation wireless radio access technologies (new RATs) may introduce on-demand transmission mechanisms for broadcast information. For example, other system information (other SI) may be used for the on-demand transmission mechanism in addition to the System Information (SI) required to be transmitted from the base station to the mobile station to establish communication between the mobile station and the base station. Other SIs may mainly include system information other than minimum required system information, and other SIs may be classified into various types and may be transmitted through a plurality of separate channels.

This patent document describes a feedback mechanism suitable for use with an on-demand transmission mechanism of broadcast information. For example, the mobile station sends a request for other SI to the base station to indicate that it needs to receive other SI of a particular type. By including feedback in requests for other SIs, feedback from the mobile station (such as beam direction) can be fed back to the base station at the same time. After receiving requests for other SIs from the mobile station, the base station decides what type of system information to transmit and considers the beam direction of the mobile station in its broadcast transmission. In such on-demand transmission mechanisms, other SIs are typically broadcast or multicast to multiple mobile stations. In some cases, the number of mobile stations requesting other SIs of a particular type is small. In particular, if the number of mobile stations requesting other SI of a particular type is one, the transmission of other SI of the particular type will be downgraded from broadcast or multicast to unicast.

The disclosed feedback mechanism may improve the transmission efficiency of broadcast channel information. Moreover, this feedback mechanism does not use additional time-frequency resources and does not affect other types of transmissions.

In the following, specific examples with various degrees of detail are set forth to illustrate aspects of the presently disclosed technology.

SUMMARY

Fig. 1 is a flow chart representation of an exemplary process for a feedback mechanism between a base station and a mobile station. The base station performs a downlink transmission operation 101 to send reference signals to the mobile station. After receiving the reference signal, the mobile station performs measurements based on the reference signal and determines corresponding feedback information (103). The mobile station then performs an uplink transmission operation 105 to send feedback information to the base station at 107. Based on the feedback information, the base station determines parameters for its broadcast channel. The base station then transmits one or more control messages to communicate the parameters to the mobile station and accordingly broadcasts the information in the broadcast channel at 109. At 111, the mobile station receives the parameters in the one or more control messages and uses the parameters to receive broadcast information.

Base station

Fig. 2 is a flow chart illustrating an example of a wireless communication method implemented at a base station. The method 200 comprises the following steps: at 202, transmitting a reference signal to a mobile station prior to broadcasting system information; receiving feedback information from the mobile station in response to the reference signal at 204; transmitting parameters for broadcasting system information to the mobile station based on the feedback information at 206; and broadcasting the system information using the parameters at 208.

In some embodiments, the reference signal transmitted by the base station is a demodulation reference signal (DMRS). The mobile station obtains a related measurement value in response to the reference signal. For example, some relevant measurements include information about Modulation and Coding Scheme (MCS), doppler effect, etc.

In some embodiments, the feedback information includes, but is not limited to, a transmission speed of the mobile station and a Modulation and Coding Scheme (MCS) index. The feedback information may further include an indicator for a demodulation reference signal pattern, the indicator further indicating a time domain or frequency domain density of the demodulation reference signal.

In some implementations, the mobile station may use a sequence of symbols to indicate a particular state of a type of feedback. In addition, a sequence number may be used to identify a particular symbol sequence. In some embodiments, it is desirable to predefine a mapping between the sequence (or corresponding sequence number) and the state of a class of feedback information. For example, as shown in fig. 3, sequences in predefined set B (e.g., sequence 4) are mapped to different states of the N-type feedback. Similarly, sequences in predefined set a are mapped to different states of one or more types of feedback.

In some embodiments, the symbol sequence or corresponding sequence number may also be used to indicate a type of other system information (other SI) requested by the mobile station. For example, the mobile station may include any sequence or sequence number from set a in its request for other SIs to request for other SIs of a particular type. If the mobile station decides to request a different type of other SI, it may use any sequence or sequence number from another set B than set a. In the particular embodiment shown in fig. 3, sequences in set a (e.g., sequence 1 and sequence 2) are mapped to other SIs of the X type, and sequences in set B (e.g., sequence 4) are mapped to other SIs of the Y type.

In some implementations, a subset of set a may be used to indicate different states of one or more types of feedback information. For example, set a contains sequence 1 (where sequence number is S1) and sequence 2 (where sequence number is S2). Sequence 1 and sequence 2 of symbols may have the same time-frequency resources. When the mobile station sends a request to the base station for other SI of a particular type (e.g., X), the mobile station may select S1 or S2 in set a and include a sequence or sequence number in its request for the other SI. When the base station receives a request for other SI, it recognizes that the mobile station is requesting X-type system information. The base station also recognizes that in the request, the mobile station simultaneously provides feedback information. For example, when the other SI request includes sequence 1 (or S1), the request instructs the mobile station to also provide feedback M of state I to indicate that its transmission speed is high. On the other hand, when the other SI request includes sequence 2 (or S2), the request instructs the mobile to also provide feedback M of state II to indicate that its transmission speed is low.

In some embodiments, a single sequence of symbols may be used to identify different states of a type of feedback information. For example, as shown in fig. 3, set B contains sequence 4 (where sequence number is S4). Sequence 4 may include different time-frequency resources. When the mobile station sends a request to the base station for other SI of a particular type (e.g., Y), the mobile station selects S4 in set B and includes a sequence or sequence number in its request for the other SI. When the base station receives a request for other SI, it recognizes that the mobile station is requesting Y-type system information. The base station also recognizes that in the request, the mobile station simultaneously provides feedback information. For example, based on the time-frequency resources of S4, the request instructs the mobile station to provide the base station with either state I N-type feedback or state II N-type feedback.

In some embodiments, parameters for broadcast transmissions include, but are not limited to: a Modulation and Coding Scheme (MCS), a demodulation reference signal (DMRS) pattern for indicating a time domain or frequency domain density of the demodulation reference signal, whether the DMRS is present in a particular symbol and/or port, and the number of retransmissions. For example, the base station may determine which DMRS pattern to use based on feedback from the mobile station. When the user entity receives the high-speed transmitted information from the base station, more time-domain DMRS symbols may be used to overcome the doppler effect. On the other hand, fewer time domain DMRS symbols may be used to obtain lower coding rate and higher reliability.

Fig. 4A illustrates an exemplary DMRS pattern including one Physical Downlink Shared Channel (PDSCH) symbol with a DMRS. One PDSCH symbol with DMRS 401 is included in a slot. Fig. 4B illustrates an exemplary DMRS pattern including two PDSCH symbols with DMRS. The slot contains two PDSCH symbols with DMRS 403. Fig. 4C illustrates an exemplary DMRS pattern including four PDSCH symbols with DMRS. The slot contains four PDSCH symbols with DMRS 405. Each DMRS sequence corresponds to a DMRS pattern using different time-frequency resources.

In some embodiments, parameters for broadcast transmissions may be communicated to the mobile station in a control message. The control message may be transmitted using a Physical Downlink Control Channel (PDCCH). The control message may also be transmitted using a Physical Broadcast Channel (PBCH) or a Physical Downlink Shared Channel (PDSCH) that carries the Remaining Minimum System Information (RMSI).

Mobile station

Fig. 5 shows a flow chart of an example of a wireless communication method implemented at a mobile station. The method 500 includes: receiving a reference signal from a base station in a broadcast channel at 502; transmitting feedback information based on the measurements according to the reference signal to the base station at 504; receiving transmission parameters for broadcasting system information from the base station, wherein the transmission parameters are determined by the feedback information, at 506; and receiving a broadcast of the system information from the base station using the transmission parameters at 508.

In some implementations, the measurements responsive to the reference signal include, for example, modulation and Coding Scheme (MCS) and doppler effect. In some implementations, the feedback information includes, but is not limited to, a transmission speed of the mobile station and a Modulation and Coding Scheme (MCS). The feedback information may further include an indicator for a demodulation reference signal pattern, the indicator further indicating a time domain or frequency domain density of the demodulation reference signal.

In some embodiments, different states of one or more types of feedback information may be indicated by using different symbol sequences. The sequence number may be used to identify the symbol sequence. A mapping between the sequence (or sequence number) and the corresponding state of a type of feedback information may be predefined. For example, as previously shown in fig. 3, sequences in predefined set B (e.g., sequence 4) are mapped to different states of the N-type feedback. Similarly, sequences in predefined set a are mapped to different states of one or more types of feedback.

In some embodiments, the mobile station may request other SIs of a particular type using a symbol sequence or corresponding sequence number. For example, in fig. 6A, the mobile station transmits a first sequence (sequence 3) 601 selected from the set a. Alternatively, a serial number S3 may be used. The first sequence (sequence 3) 601 indicates that the mobile station requests other SI of type X. In this case, the mobile station does not provide any feedback to the base station. Fig. 6B shows that in some implementations, a mobile station may transmit two sequences from set a: a first sequence (sequence 3) 601 and a second sequence (sequence 2) 603 (or alternatively, sequence numbers S3 and S2). The first sequence (sequence 3) 601 indicates that the mobile station requests other SI of type X from the base station. In addition, the second sequence (sequence 2) 603 instructs the mobile station to also provide feedback about its transmission speed.

As discussed above, in some embodiments, a subset of set a may be used to indicate different states of one or more types of feedback information. For example, set a contains sequence 1 (where sequence number is S1) and sequence 2 (where sequence number is S2). Sequence 1 and sequence 2 of symbols may have the same time-frequency resources. When the mobile station sends a request to the base station for other SI of a particular type (e.g., X), the mobile station may select S1 or S2 in set a and include a sequence or sequence number in its request for the other SI. When the base station receives a request for other SI, it recognizes that the mobile station is requesting X-type system information. The base station also recognizes that in the request, the mobile station simultaneously provides feedback information. For example, when the other SI request includes sequence 1 (or S1), the request instructs the mobile station to also provide feedback M of state I to indicate that its transmission speed is high. On the other hand, when the other SI request includes sequence 2 (or S2), the request instructs the mobile station to also provide feedback M of state II to indicate that its transmission speed is low.

In some embodiments, parameters for broadcast transmissions may be communicated to the mobile station in a control message. The control message may be transmitted using a Physical Downlink Control Channel (PDCCH). The configuration message may also be transmitted using a Physical Broadcast Channel (PBCH) or a Physical Downlink Shared Channel (PDSCH) that carries the Remaining Minimum System Information (RMSI).

In some implementations, parameters for broadcast transmissions include, but are not limited to: a Modulation and Coding Scheme (MCS), a demodulation reference signal (DMRS) pattern for indicating a time domain or frequency domain density of the demodulation reference signal, whether the DMRS is present in a particular symbol and/or port, and the number of retransmissions. For example, the parameters for the broadcast channel include MCS. The mobile station uses the parameters to demodulate and decode the broadcast communication accordingly. In some implementations, the parameters may include a DMRS pattern, such as shown in fig. 4A-C. The mobile station performs channel estimation and demodulation based on the received DMRS pattern.

Fig. 7 illustrates an example of a wireless communication system in which techniques according to one or more embodiments of the present technology may be applied. The wireless communication system 700 may include one or more Base Stations (BSs) 705a, 705b, one or

more wireless devices

710a, 710b, 710c, 710d, and an access network 725. Base stations 705a, 705b may provide wireless services to

wireless devices

710a, 710b, 710c, and 710d in one or more wireless sectors. In some implementations, the base stations 705a, 705b include directional antennas to generate two or more directional beams to provide wireless coverage in different sectors.

Access network 725 may communicate with one or more base stations 705a, 705b. In some implementations, access network 725 includes one or more base stations 705a, 705b. In some implementations, access network 725 communicates with a core network (not shown in fig. 7) that provides connectivity to other wireless and wireline communication systems. The core network may include one or more service subscription databases to store information about subscribed

wireless devices

710a, 710b, 710c, and 710 d. The first base station 705a may provide wireless services based on a first radio access technology, while the second base station 705b may provide wireless services based on a second radio access technology. Depending on the deployment scenario, base stations 705a and 705b may be co-located or may be installed separately in the field. Access network 725 may support a number of different radio access technologies.

In some implementations, a wireless communication system may include multiple networks using different wireless technologies. Dual-mode or multi-mode wireless devices include two or more wireless technologies that may be used to connect to different wireless networks.

Fig. 8 is a block diagram representation of a portion of a radio station. A radio station 805 such as a base station or wireless device may include processor electronics 810, such as a microprocessor, that implement one or more of the wireless techniques presented in this document. Radio 805 may include transceiver electronics 815 to transmit and/or receive wireless signals through one or more communication interfaces, such as antenna 820. Radio station 805 may include other communication interfaces for transmitting and receiving data. Radio station 805 may include one or more memories configured to store information such as data and/or instructions. In some implementations, the processor electronics 810 may include at least a portion of the transceiver electronics 815. In some implementations, at least some of the disclosed techniques, modules, or functions are implemented using radio station 805.

Some embodiments described herein are described in the general context of methods or processes, which may be implemented in one embodiment by a computer program product embodied in a computer-readable medium including computer-executable instructions, such as program code, executed by computers in network environments. Computer readable media can include removable and non-removable storage devices including, but not limited to, read Only Memory (ROM), random Access Memory (RAM), compact Discs (CD), digital Versatile Discs (DVD), and the like. Thus, the computer readable medium may include a non-transitory storage medium. Generally, program modules may include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Computer or processor executable instructions, associated data structures, and program modules represent examples of program code for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps or processes.

Some of the disclosed embodiments may be implemented as a device or module using hardware circuitry, software, or a combination thereof. For example, a hardware circuit implementation may include discrete analog and/or digital components, for example, integrated as part of a printed circuit board. Alternatively or additionally, the disclosed components or modules may be implemented as Application Specific Integrated Circuits (ASICs) and/or as Field Programmable Gate Array (FPGA) devices. Some embodiments may additionally or alternatively include a Digital Signal Processor (DSP), which is a special purpose microprocessor, having an architecture optimized for the operational requirements of digital signal processing associated with the disclosed functionality of the present application. Similarly, the various components or sub-components within each module may be implemented in software, hardware, or firmware. Any of the connection methods and media known in the art may be used to provide connectivity between modules and/or components within modules, including but not limited to communications over the internet, wired or wireless networks using appropriate protocols.

Although this patent document contains many specifics, these should not be construed as limitations on the scope of any invention or of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of particular inventions. Certain features that are described in this patent document in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Furthermore, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

Similarly, although operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Furthermore, the separation of various system components in the embodiments described in this patent document should not be understood as requiring such separation in all embodiments.

Only a few implementations and examples are described, and other implementations, enhancements, and variations may be made based on what is described and shown in this patent document.

Claims

1. A method of wireless communication, comprising:

transmitting a reference signal to a mobile station before broadcasting system information;

receiving feedback information of the reference signal from the mobile station, the feedback information being fed back by a symbol sequence corresponding to request information for broadcasting the system information, the symbol sequence belonging to a symbol sequence set a, and the symbol sequence set a being mapped to one type of other system information, the symbol sequence being mapped to a state of one type of feedback information;

transmitting parameters for broadcasting system information to the mobile station based on the feedback information; and

the system information is broadcast using the parameters.

2. The method of claim 1, wherein the reference signal comprises a demodulation reference signal, DMRS.

3. The method of claim 1, wherein the parameter comprises a modulation coding scheme, MCS, index.

4. The method of claim 1, wherein the parameter comprises an indication of a demodulation reference signal type.

5. The method of claim 4, wherein the demodulation reference signal type indicates a time domain or frequency domain density of the demodulation reference signal.

6. The method of claim 1, wherein the feedback information comprises a modulation coding scheme, MCS, index.

7. The method of claim 1, wherein the feedback information comprises an indication of a demodulation reference signal type.

8. The method of claim 7, wherein the demodulation reference signal type indicates a time domain or frequency domain density of the demodulation reference signal.

9. The method of claim 1, wherein the request includes a first symbol sequence indicating a requested type of system information.

10. The method of claim 9, wherein the first symbol sequence indicates a first state of a type of feedback information.

11. The method of claim 10, wherein the request includes a second symbol sequence indicating a requested type of system information, the first and second symbol sequences selected from a predetermined set of sequences.

12. The method of claim 11, wherein the second symbol sequence indicates a second state of the class of feedback information, the first and second symbol sequences using the same time-frequency resources.

13. A method of wireless communication, comprising:

receiving a reference signal from a base station through a broadcast channel;

transmitting feedback information based on a measurement in response to the reference signal to the base station, the feedback information being fed back through a symbol sequence corresponding to request information for broadcasting system information, the symbol sequence belonging to a symbol sequence set a, and the symbol sequence set a being mapped to one type of other system information, the symbol sequence being mapped to a state of one type of feedback information;

receiving parameters for broadcasting system information from the base station, wherein the parameters are determined by the feedback information; and

the system information is received from the base station using the parameters.

14. The method of claim 13, wherein the reference signal comprises a demodulation reference signal, DMRS.

15. The method of claim 13, wherein the parameter comprises a modulation coding scheme, MCS, index.

16. The method of claim 13, wherein the parameter comprises an indication of a demodulation reference signal type.

17. The method of claim 16, wherein the demodulation reference signal type indicates a time domain or frequency domain density of the demodulation reference signal.

18. The method of claim 13, wherein the feedback information comprises a modulation coding scheme, MCS, index.

19. The method of claim 13, wherein the feedback information comprises an indication of a demodulation reference signal type.

20. The method of claim 19, wherein the demodulation reference signal type indicates a time domain or frequency domain density of the demodulation reference signal.

21. The method of claim 13, wherein the request includes a first symbol sequence indicating a requested type of system information.

22. The method of claim 21, wherein the first symbol sequence indicates a first state of a type of feedback information.

23. The method of claim 22, wherein the request includes a second symbol sequence indicating a requested type of system information, the first and second symbol sequences selected from a predetermined set of sequences.

24. The method of claim 23, wherein the second symbol sequence indicates a second state of the class of feedback information, the first and second symbol sequences using the same time-frequency resources.

25. A wireless communication device, comprising:

a memory for storing code; and

a processor in communication with the memory and operable to execute the code to cause the wireless communication device to:

the system information is broadcast using the parameters.

26. The apparatus of claim 25, wherein the reference signal comprises a demodulation reference signal, DMRS.

27. The apparatus of claim 25, wherein the parameter comprises a modulation coding scheme, MCS, index.

28. The apparatus of claim 25, wherein the parameter comprises an indication of a demodulation reference signal type.

29. The apparatus of claim 28, wherein the demodulation reference signal type indicates a time domain or frequency domain density of the demodulation reference signal.

30. The apparatus of claim 25, wherein the feedback information comprises a modulation coding scheme, MCS, index.

31. The apparatus of claim 25, wherein the feedback information comprises an indication of a demodulation reference signal type.

32. The apparatus of claim 31, wherein the demodulation reference signal type indicates a time domain or frequency domain density of the demodulation reference signal.

33. The apparatus of claim 25, wherein the request comprises a first symbol sequence indicating a requested type of system information.

34. The apparatus of claim 33, wherein the first symbol sequence indicates a first state of a type of feedback information.

35. The apparatus of claim 34, wherein the request comprises a second symbol sequence indicating a requested type of system information, the first and second symbol sequences selected from a predetermined set of sequences.

36. The apparatus of claim 35, wherein the second symbol sequence indicates a second state of the class of feedback information, the first and second symbol sequences using the same time-frequency resources.

37. A wireless communication device, comprising:

a memory for storing code; and

receiving a reference signal from a base station through a broadcast channel;

a broadcast of the system information is received from the base station using the parameters.

38. The apparatus of claim 37, wherein the reference signal comprises a demodulation reference signal, DMRS.

39. The apparatus of claim 37, wherein the parameter comprises a modulation coding scheme, MCS, index.

40. The apparatus of claim 37, wherein the parameter comprises an indication of a demodulation reference signal type.

41. The apparatus of claim 40, wherein the demodulation reference signal type indicates a time domain or frequency domain density of the demodulation reference signal.

42. The apparatus of claim 37, wherein the feedback information comprises a modulation coding scheme, MCS, index.

43. The apparatus of claim 37, wherein the feedback information comprises an indication of a demodulation reference signal type.

44. The apparatus of claim 43, wherein the demodulation reference signal type indicates a time domain or frequency domain density of the demodulation reference signal.

45. The apparatus of claim 37, wherein the request comprises a first symbol sequence indicating a requested type of system information.

46. The apparatus of claim 45, wherein the first symbol sequence indicates a first state of a type of feedback information.

47. The apparatus of claim 46, wherein the request includes a second symbol sequence indicating a requested type of system information, the first and second symbol sequences selected from a predetermined set of sequences.

48. The apparatus of claim 47, wherein the second symbol sequence indicates a second state of the type of feedback information, the first and second symbol sequences using the same time-frequency resources.