METHOD AND APPARATUS FOR PROVIDING USER EQUIPMENT ACCESS TO MILLIMETER WAVE STATIONS THROUGH A MICROWAVE STATION
A method for providing user equipment access to millimeter wave stations through a microwave station includes receiving an indication of millimeter wave stations operating within a microwave coverage area of a microwave station. In a microwave band, information associated with the millimeter wave stations is broadcasted to user equipment in the microwave coverage area. A request is sent to the millimeter wave stations to transmit configuration signals over a microwave band. An instruction is transmitted over the microwave band to the user equipment to perform proximity measurements of the configuration signals. According to the proximity measurements, a request is sent to a particular millimeter wave station to transmit beamforming signals over a millimeter wave band. An instruction is transmitted over the microwave band to the user equipment to perform beamforming measurements of the beamforming signals. According to the beamforming measurements, the user equipment is switched to millimeter wave operation.
The present disclosure relates in general to cellular communication systems and more particularly to a method and apparatus for providing user equipment access to millimeter wave stations through a microwave station.
BACKGROUNDThe amount of wireless data is growing at an unprecedented rate in the last few years, pushing the capacity of current macro cellular deployments. Cellular communications systems, which utilize microwave (uWave) spectrum bands (300 MHz to 3 GHz), are becoming capacity limited due to interference and traffic load. The use of high frequency bands, where vast amounts of bandwidth are available, is considered to be a crucial element for future generation communication systems. The use of millimeter wave (mmWave) frequency bands (e.g., 28, 38, 60, and 73 GHz) can mitigate the problem of capacity currently observed in microwave systems. Propagation in the mmWave band is more challenging than in the uWave band, resulting in a more stringent link budget at mmWave bands than at uWave bands. This can be somehow compensated by using beamforming. In order to achieve significant beamforming gain, channel knowledge at the transmitter is needed. However, when a user equipment (UE) wants to perform initial access in the mmWave band, such channel information is not available since the UE has not yet exchanged information with the mmWave eNodeB (eNB) base transceiver station. This would unacceptably limit the range on the mmWave eNB.
SUMMARYFrom the foregoing, it may be appreciated by those skilled in the art that a need has arisen for a technique to establish access to millimeter wave operation for user equipment operating in a microwave band. In accordance with the present disclosure, a method and apparatus for providing user equipment access to millimeter wave stations through a microwave station are provided that greatly reduce or substantially eliminate problems and disadvantages associated with current microwave operating techniques.
A method for providing user equipment access to millimeter wave stations through a microwave station includes receiving an indication of millimeter wave stations operating within a microwave coverage area of a microwave station. In a microwave band, information associated with the millimeter wave stations is broadcasted to user equipment in the microwave coverage area. A request is sent to the millimeter wave stations to transmit configuration signals over a microwave band. An instruction is transmitted over the microwave band to the user equipment to perform proximity measurements of the configuration signals. According to the proximity measurements, a request is sent to a particular millimeter wave station to transmit beamforming signals over a millimeter wave band. An instruction is transmitted over the microwave band to the user equipment to perform beamforming measurements of the beamforming signals. According to the beamforming measurements, the user equipment is switched to millimeter wave operation.
The present disclosure describes many technical advantages over conventional microwave telecommunication operating systems. For example, one technical advantage is to utilize a microwave station in coordinating user equipment operation in a millimeter wave band. Another technical advantage is to provide an access interface between a millimeter wave station and user equipment in determining whether the user equipment can switch to millimeter wave operation. Other technical advantages may be readily apparent to and discernable by those skilled in the art from the following figures, description, and claims.
For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings, wherein like reference numerals represent like parts, in which:
Method 200 relies on using the uWave layer to exchange information between the mmWave eNB station 104 and the UE 106. A cellular link in the uWave band is established between the uWave eNB station 102 and the UE 106. The mmWave eNB stations 104 and the uWave eNB station 102 operate in a coordinated manner. The feedback used for performing the necessary beamforming for the mmWave eNB station 104 is exchanged via the uWave eNB station 102. The measurements necessary for initiating the mmWave beamforming are performed in the mmWave band.
When the potential proximity determination is triggered, the uWave eNB station 102 configures the UE 106 with information regarding zero power CSI-RS signals, in one embodiment, using existing radio resource control (RRC) messaging and instructs mmWave eNB stations 104 to transmit non-zero power (NZP) CSI-RS signals in the uWave band. The messaging for the non-zero power (NZP) CSI-RS signals may include information such as CSI-RS antenna port configurations used, code, power, and any other parameters desired to be detected by UE 106. The NZP CSI-RS signals may be semi-persistently scheduled or be a “one-shot” message. Note that signals other than CSI-RS could be used. Using other signal types would require creating new antenna ports and new signaling similar to the one used to signal CSI-RS might be implemented, especially if UE 106 monitors a potentially large number of mmWave eNB stations 104. Note also that the first part (configuring ZP CSI-RS) is optional. RRC messaging can be used for sending ZP CSI-RS configuration. The uWave eNB station 102 may also create blank spaces by scheduling and not scheduling transmission on some physical resource blocks (PRBs) when the NZP CSI-RS is transmitted by the mmWave eNB station 104. This however would be highly inefficient as the CSI-RS (ZP and NZP) signals are designed with low overhead and to perform measurements, such as the proximity measurement, in a way that is as least disruptive as possible to the existing cellular communication.
Once the ZP and NZP CSI-RS configurations have been received by the UE 106, the uWave eNB station 102 instructs the UE 106 to perform measurements. This message could be a dedicated RRC message, a message similar to the ones used to trigger periodic or aperiodic CSI-RS reporting, or a new type of downlink control information (DCI) message. Multiple UEs 106 could monitor the same CSI-RS signal from a given mmWave eNB station 104 at the same time. In that sense, the CSI-RS (ZP and NZP) signal could be communicated to UEs 106 either via a unicast message, a multicast message, or even a broadcast message.
The UE 106 then reports the measurements to uWave eNB 102. The reporting could be done with a dedicated RRC message or a message similar (or the same) as CSI reporting. The measurement report may contain power measurements, quality measurements, SIR/SINR/SNR measurements, reference symbol received power (RSRP), radio signal strength indicator (RSSI), and so forth. This report may be autonomously sent by the UE 106 or the uWave eNB station 102 may allocate resources for the reporting. Once the UE 106 reports the measurements, and the uWave eNB station 102 receives them, the uWave eNB station 102 may process the measurements from the measurement report and then assess potential proximity of UE 106 to a mmWave eNB station 104 and determine whether there is actual proximity to a mmWave eNB station 104 or not.
The mmWave eNB information broadcast by uWave eNB station 102 to the UE 106 may be provided using broadcast RRC signaling (SIB), dedicated RRC signal, or a combination of both. This information may be provided before or after the trigger to initiate proximity establishment. The information may comprise a flag to indicate if there is one or more mmWave eNB stations 104 around, a frequency at which the mmWave eNB stations 104 operate, a mode (such as frequency division duplex (FDD) and time division duplex (TDD)) and associated configuration, coordinates of mmWave eNB stations 104, a list of signal location in the uWave band where mmWave eNB stations 104 transmit discovery signals, and a list of D2D code/location to monitor if used. A signal location may comprise a signal index, a subframe index (or a list of subframe indexes), a frequency index (PRB list), parameters of a hopping sequence, and so forth. The signal location may be semi-persistently signaled.
Once this information has been provided, the uWave eNB station 102 receives a proximity report from the UE 106 to indicate its proximity to mmWave eNB stations 104. This report may be autonomously sent by the UE 106 or the uWave eNB station 102 may allocate resources for the reporting. Also, the uWave eNB station 102 may instruct mmWave eNB stations 104 to transmit these discovery signals and may allocate resources for such transmission. If the proximity determination is based on geographical coordinates, the uWave eNB station 102 does not need to allocate resources to the mmWave eNB station in the uWave band. Once the report from the UE is received, the uWave eNB station 102 determines if there is proximity and may decide to initiate the beamforming procedure.
Once the uWave operation is established, there may be a trigger to attempt to switch UE 106 to the mmWave band. This trigger may be initiated by uWave eNB station 102 to initiate the proximity establishment procedure and switch UE 106 to the mmWave band based on traffic conditions. This trigger may be initiated by UE 106 if it decides that more bit rate is needed. A request may be made by UE 106 that may or may not be granted by uWave eNB station 102 or other network entities. This trigger may also be initiated by network entities (such as a Mobility Management Entity unit or High Level Architecture unit) by sending a command to uWave eNB station 102 to switch the UE 106 to the mmWave band.
Prior to mmWave band operation, a beam pattern is first established for use by mmWave eNB station 104 and, depending on the entity establishing the beam pattern, communicated to the appropriate entities. In one embodiment, uWave eNB station 102 establishes the beam pattern. In another embodiment, mmWave eNB station 104 chooses its own beam pattern. In yet another embodiment, the beam pattern is determined by another network entity and communicated to both uWave eNB station 102 and mmWave eNB stations 104. The establishment of the beam pattern does not need to occur each time upon performing the beamforming operation. The beam pattern may be pre-determined once and then would always apply for the beamforming operation. There may be a codebook entry corresponding to each beam pattern.
The configuration for the beam pattern indicates the resources where each of the beams will be transmitted. The beam pattern may be scheduled on demand when needed for a measurement, semi-persistently scheduled in an on/off manner or with a trigger from uWave eNB station 102, or persistently scheduled, with the mmWave eNB always using the same pattern. While the pattern is always the same, the transmission duration or time (on/off) could be controlled by uWave eNB station 102 to avoid interference or for power saving purposes. The signal transmitted on the beam could be a pilot sequence to perform measurements or a pilot sequence and a short message to perform better quality measurements and provide additional information that identifies the beam direction and the cell as needed.
Once the beam pattern has been established, mmWave eNB stations 104 transmit the beam according to the pattern. The beamforming signals transmitted by mmWave eNB stations 104 may be pilot signals or any other type of signal that mmWave eNB stations 104 are configured to transmit. The only requirement of these beamforming signals are that they are sufficient to allow performance of power and/or quality measurements. uWave eNB station 102 may notify mmWave eNB stations 104 of when/where the beamforming signals are to be sent during registration of the mmWave eNB stations 104 or as part of the request to transmit the beamforming signals. In other embodiments, when/where the beamforming signals are to be sent is determined by mmWave eNB stations 104 or other network entities.
The request to instruct the UE 106 to perform the measurements can be done by sending a dedicated RRC message, by using physical layer signaling using a specific DCI-like message, or any other messaging protocol. The message may include an indication to perform the measurements, the time/frequency location of where to perform the measurements, and resources for sending the beamforming report.
uWave eNB station 102 receives the beamforming report from the UE 106 in the uWave band. The beamforming report may be sent on resources allocated by uWave eNB 102 or may be autonomously sent by the UE 106. The beamforming report may include power measurements (e.g., RSRP, RXLEV), quality measurements (RXQUAL), and SNR/SINR/SIR measurements. Based at least in part on these measurements, uWave eNB station 102 can then decide whether or not to switch UE 106 to the mmWave eNB station 104.
When the UE 106 receives the pattern, it attempts to obtain the beam reference signal on each of the received beams in the mmWave domain. The UE 106 performs measurements, such as RSRP, on this beam reference signal and can then determine which beam is appropriate for communication with the particular mmWave eNB station 104. Once the suitable beam is/are identified based on the criteria discussed above, the UE 106 then reports to the uWave eNB station 102 in the uWave band the preferred beam(s). The criteria to determine the appropriate beam may be signaled by the mmWave eNB station 104, uWave eNB station 102, or may be provisioned in the UE 106 by other means (for instance might be a maximum (minimum) value of signal strength out of all the received beamformed signals). An appropriate beam may be a best overall beam (in terms of RSRP, SINR, etc.), a beam whose measurement exceeds a RSRP or SINR threshold, a beam good enough to meet the frame error rate (FER) requirements for the UE 106, or any other desired characteristics.
The beamforming report may include a signal to interference noise ratio (SINR), signal to noise ratio (SNR), and signal to interference ration (SIR) value for each of the beams and a bitmap indicating which beam(s) are suitable. The beamforming report may also include information related to the beamformer used at the UE 106, e.g., how many antennas are used by the UE 106 to perform beamforming measurements, such a subset of the antennas (e.g., 4 out of 16), thereby notifying uWave eNB station 102 that it could do better in terms of overall beamforming gain. The reason to only use a subset of antennas would be to have a wider beam and be less sensitive to impairments resulting from mobility.
Once the beamforming report has been received from UE 106, uWave eNB station 102 may communicate the beamforming report to the mmWave eNB station 104. In another embodiment, uWave eNB station 102 may process the beamforming report and may communicate results of the processing to the mmWave eNB station 104. As a result, both the UE 106 and the mmWave eNB station 104 know which beamforming coefficients (such as a codeword index, a codeband index, or with the coefficients encoded in a reference signal such as analog feedback) to use to start the initial mmWave band access procedure.
The secondary storage 1204 is typically comprised of one or more disk drives or tape drives and is used for non-volatile storage of data and as an over-flow data storage device if RAM 1208 is not large enough to hold all working data. Secondary storage 1204 may be used to store programs that are loaded into RAM 1208 when such programs are selected for execution. The ROM 1206 is used to store instructions and perhaps data that are read during program execution. ROM 1206 is a non-volatile memory device that typically has a small memory capacity relative to the larger memory capacity of secondary storage 1204. The RAM 1208 is used to store volatile data and perhaps to store instructions. Access to both ROM 1206 and RAM 1208 is typically faster than to secondary storage 1204. Additional processors and memory devices may be incorporated based on the function of each component within uWave eNB station 102, mmWave eNB station 104, and UE 106.
Network/component connectivity devices 1212 may be any component or collection of components that allow processing system 1200 to communicate with other devices/components and/or a user. For example, one or more of network/component connectivity devices 1212 may be adapted to communicate data, control, or management messages from processor 1204 to applications installed on the host device and/or a remote device. As another example, one or more of network/component connectivity devices 1112 may be adapted to allow a user or user device (e.g., personal computer (PC), etc.) to interact/communicate with the processing system 1200.
As discussed above, the processing system 1200 may be included in a network device that is accessing, or part otherwise of, a telecommunications network 100. In one example, the processing system 1200 may be a network-side device in a wireless or wireline telecommunications network 100, such as a base station, a relay station, a scheduler, a controller, a gateway, a router, an applications server, or any other device in telecommunications network 100. In other embodiments, the processing system 1200 is in a user-side device accessing a wireless or wireline telecommunications network 100, such as a mobile station, a user equipment (UE), a personal computer (PC), a tablet, a wearable communications device (e.g., a smartwatch, etc.), or any other device adapted to access telecommunications network 100. In some embodiments, one or more of network/component connectivity devices 1212 connects the processing system 1200 to a transceiver adapted to transmit and receive signaling over telecommunications network 100.
The transceiver 1300 may transmit and receive signaling over any type of communications medium. In some embodiments, the transceiver 1300 transmits and receives signaling over a wireless medium. For example, the transceiver 1300 may be a wireless transceiver adapted to communicate in accordance with a wireless telecommunications protocol, such as a cellular protocol (e.g., long-term evolution (LTE), etc.), a wireless local area network (WLAN) protocol (e.g., Wi-Fi, etc.), or any other type of wireless protocol (e.g., Bluetooth, near field communication (NFC), etc.). In such embodiments, the network-side interface 1302 comprises one or more antenna/radiating elements. For example, the network-side interface 1302 may include a single antenna, multiple separate antennas, or a multi-antenna array configured for multi-layer communication, e.g., single input multiple output (SIMO), multiple input single output (MISO), multiple input multiple output (MIMO), etc. In other embodiments, the transceiver 1300 transmits and receives signaling over a wireline medium, e.g., twisted-pair cable, coaxial cable, optical fiber, etc. Specific processing systems and/or transceivers may utilize all of the components shown, or only a subset of the components, and levels of integration may vary from device to device.
In some embodiments, some or all of the functions or processes of the one or more of the devices are implemented or supported by a computer program that is formed from computer readable program code and that is embodied in a computer readable medium. The phrase “code” includes any type of computer code, including source code, object code, and executable code. The phrase “computer readable medium” includes any type of medium capable of being accessed by a computer, such as read only memory (ROM), random access memory (RAM), a hard disk drive, a compact disc (CD), a digital video disc (DVD), or any other type of memory.
It may be advantageous to set forth definitions of certain words and phrases used throughout this patent document. The terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation. The term “or” is inclusive, meaning and/or. The phrases “associated with” and “associated therewith,” as well as derivatives thereof, mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like.
While this disclosure has described certain embodiments and generally associated methods, alterations and permutations of these embodiments and methods will be apparent to and readily discernable by those skilled in the art. Accordingly, the above description of example embodiments does not define or constrain this disclosure. For example, although the embodiments are expressed using uWave and mmWave bands, the embodiments are applicable to scenarios such as dense networks. In this example, mmWave eNB stations 104 could represent low powered base stations for small cells. Other changes, substitutions, and alterations are also possible without departing from the scope of this disclosure as defined by the following claims.
Claims
1. A method for providing user equipment access to a millimeter wave station through a microwave station, the method comprising:
- receiving, by the microwave station from the user equipment, a first measurement report of a reference signal associated with the millimeter wave station, the first measurement report providing a basis to determine a proximity of the user equipment to the millimeter wave station;
- transmitting, by the microwave station to the user equipment, a first configuration for receiving a plurality of beamforming signals transmitted by the millimeter wave station;
- receiving, by the microwave station from the user equipment, a second measurement report of the plurality of beamforming signals; and
- informing the user equipment, by the microwave station, to receive beamformed transmissions from the millimeter wave station, wherein parameters for the beamformed transmissions are selected in accordance to the second measurement report.
2. The method of claim 1, further comprising:
- communicating, by the microwave station, to the millimeter wave station resources for transmitting the plurality of beamforming signals.
3. The method of claim 1, further comprising:
- communicating, by the microwave station, to the millimeter wave station the second measurement report or an evaluation of the second measurement report.
4. The method of claim 1, wherein the reference signal is transmitted over a microwave band from a beacon station coupled to the millimeter wave station.
5. The method of claim 4, wherein the first measurement report is received on a first carrier of th microwave band and the reference signal is transmitted on a second carrier of the microwave band.
6. The method of claim 5, further comprising:
- sending a request, by the microwave station, to the beacon station to transmit the reference signal over the second carrier of the microwave band; and
- transmitting, by the microwave station, over the first carrier of the microwave band a request to the user equipment to perform proximity measurements of the reference signal.
7. The method of claim 1, further comprising:
- receiving at the microwave station an indication of millimeter wave stations operating within a microwave coverage area of the microwave station; and
- broadcasting, by the microwave station, to the user equipment in a first carrier of a microwave band information associated with the millimeter wave stations in the microwave coverage area.
8. The method of claim 1, further comprising:
- determining from the first measurement report whether the user equipment is in proximity of the millimeter wave station;
- sending, by the microwave station, a request to the millimeter wave station to transmit the plurality of beamforming signals over a millimeter wave band in response to the user equipment being in proximity of the millimeter wave station; and
- transmitting, by the microwave station, over a first carrier of the microwave band a request to the user equipment to perform beamforming measurements of the beamforming signals for the second measurement report.
9. The method of claim 1, further comprising:
- triggering proximity determination and beamforming operations in response to any one of traffic conditions exceeding a particular threshold, user equipment request, and network entity request.
10. The method of claim 1, further comprising:
- receiving, by the microwave station, a first stage beamforming measurement report from the user equipment;
- transmitting, by the microwave station, a configuration for a second stage beamforming transmission in accordance to the first stage beamforming measurement report; and
- receiving, by the microwave station, a second stage beamforming measurement report from the user equipment.
11. The method of claim 1, further comprising:
- receiving, by the microwave station, a failure indication for user equipment access to the millimeter wave band; and
- continuing microwave band operation between the use equipment and the microwave station in response to millimeter wave band access failure.
12. An apparatus at a microwave station for providing user equipment access to millimeter wave stations, comprising:
- a memory configured to store data and instruction code;
- a processor, upon executing the instruction code, configured to: receive, by the microwave station from the user equipment, a first measurement report of a reference signal associated with the millimeter wave station, the first measurement report providing a basis to determine a proximity of the user equipment to the millimeter wave station; transmit, by the microwave station to the user equipment, a first configuration for receiving a plurality of beamforming signals transmitted by the millimeter wave station; receive, by the microwave station from the user equipment, a second measurement report of the plurality of beamforming signals; and inform the user equipment, by the microwave station, to receive beamformed transmissions from the millimeter wave station, wherein parameters for the beamformed transmissions are selected in accordance to the second measurement report.
13. The apparatus of claim 12, wherein the processor is further configured to:
- communicate to the millimeter wave station resources for transmitting the plurality of beamforming signals.
14. The apparatus of claim 12, wherein the processor is further configured to:
- communicate to the millimeter wave station the second measurement report or an evaluation of the second measurement report.
15. The apparatus of claim 12, wherein the reference signal is transmitted from a beacon station coupled to the millimeter wave station.
16. The apparatus of claim 15, wherein the first measurement report is received on a first carrier of a microwave band and the reference signal is transmitted on a second carrier of the microwave band.
17. The apparatus of claim 16, wherein the processor is further configured to:
- send a request to the beacon station to transmit the reference signal over the second carrier of the microwave band; and
- transmit over the first carrier of the microwave band a request to the user equipment to perform proximity measurements of the reference signal.
18. The apparatus of claim 12, wherein the processor is further configured to:
- receive at the microwave station an indication of millimeter wave stations operating within a microwave coverage area of the microwave station; and
- broadcast to the user equipment in a first carrier of a microwave band information associated with the millimeter wave stations in the microwave coverage area.
19. The apparatus of claim 12, wherein the processor is further configured to:
- determine from the first measurement report whether the user equipment is in proximity of the millimeter wave station;
- send a request to the millimeter wave station to transmit the plurality of beamforming signals over a millimeter wave band in response to the user equipment being in proximity of the millimeter wave station; and
- transmit over a first carrier of the microwave band a request to the user equipment to perform beamforming measurements of the beamforming signals for the second measurement report.
20. The apparatus of claim 12, wherein the processor is further configured to:
- trigger proximity determination and beamforming operations in response to any one of traffic conditions exceeding a particular threshold, user equipment request, and network entity request.
21. The apparatus of claim 12, wherein the processor is further configured to:
- receive a first stage beamforming measurement report from the user equipment;
- transmit a configuration for a second stage beamforming transmission in accordance to the first stage beamforming measurement report; and
- receive second stage beamforming measurement report from the user equipment.
22. The apparatus of claim 12, wherein the processor is further configured to:
- receive a failure indication for user equipment access to the millimeter wave band; and
- continue microwave band operation between the use equipment and the microwave station in response to millimeter wave band access failure.
Type: Application
Filed: Oct 14, 2015
Publication Date: Apr 20, 2017
Inventors: Philippe Sartori (Plainfield, IL), Vipul Desai (Palatine, IL), George Calcev (Hoffman Estates, IL), Anthony C.K. Soong (Plano, TX), Jialing Liu (Palatine, IL), Qian Cheng (Aurora, IL), Weimin Xiao (Hoffman Estates, IL)
Application Number: 14/883,427