DIRECT OPTICAL TO RF TRANSCEIVER FOR A WIRELESS SYSTEM
A hybrid optical-RF device, called a “stamp cell” herein, may be a small, passive repeating device that is designed to be placed close to User Equipment (UE) such that the UE only needs to reach a few meters using high frequency RF signals. The stamp cell may directly convert the received RF signal to an optical signal which may be transmitted to an optical receiver mounted on a traditional cell tower. Similarly, in the downlink direction, the stamp cell may receive optical signals from the cell tower and convert the optical signals to high frequency RF signals, which may be received by the UE.
This application is a Continuation of co-pending U.S. patent application Ser. No. 16/234,489, titled “DIRECT OPTICAL TO RF TRANSCEIVER FOR A WIRELESS SYSTEM,” filed Dec. 27, 2018, which is a Continuation of U.S. Pat. No. 10,230,465, titled “DIRECT OPTICAL TO RF TRANSCEIVER FOR A WIRELESS SYSTEM,” filed Jan. 23, 2018, the contents of which are hereby incorporated by reference.
BACKGROUNDEmerging wireless standards for wireless cellular networks can use very high radio frequency bands (e.g., 14 gigahertz (GHz) and higher). A 5G New Radio (NR), for example, may be operable over a wide range of frequency bands, including very high frequency bands, such as bands from 14 GHz-100 GHz.
A primary benefit of using these frequencies is the large amount of spectrum can provide very high bandwidths. A drawback of high frequency radio transmissions, however, is that it can be difficult to make transceivers that can reach longer ranges (e.g., >100 meters) without requiring an exponential increase in power.
The following detailed description refers to the accompanying drawings. The same reference numbers in different drawings may identify the same or similar elements.
A hybrid optical-Radio Frequency (RF) device, referred to as a “stamp cell” herein, is described. The stamp cell may be a small, passive repeating device that is designed to be placed close to User Equipment (UE) such that transmissions from the UE, using the high frequency RF signals, only need to reach a few meters. The stamp cell may directly convert the received RF signal to an optical signal which may be transmitted to an optical receiver mounted on, for example, a traditional cell tower. Similarly, in the downlink direction, the stamp cell may receive optical signals from the cell tower and convert the optical signals to high frequency RF signals, which may be received by the UE.
Stamp cells 150 may be passive devices that do not require a battery or other power source. Alternatively, stamp cells 150 may be an active device, such as devices powered with a battery or connected to the power grid. Stamp cells 150 may be relatively small devices, such as electrical devices that have an area on the order of about a few square centimeters up to about a square meter. Stamp cells 150 may also be relatively inexpensive, and may thus be economically deployed relatively densely.
Stamp cells 150 may be able to communicate, using high frequency RF signals (e.g. 14 GHz and higher), over relatively short distances (e.g., on the order of about a few meters). The use of the high frequencies may enable stamp cells 150, when in range of a user, to provide high bandwidth data streams to the user.
Assume pedestrian 130 is using a UE that is in range of a stamp cell 150 (e.g., a stamp cell mounted on street light 140). In the uplink direction (i.e., UE to network direction), the stamp cell may receive RF signals from the UE, convert the RF signals to optical signals, and transmit the optical signals to cell tower 160. Cell tower 160 may include a corresponding optical receiver to receive the optical signals and transmit the signals to a backbone network 170. The conversion from RF to optical signals, by stamp cell 150, may be performed passively in which the energy of the RF signal and/or energy derived from optical signals received from cell tower 160, is used to power the generation of the optical signal. Similarly, in the downlink direction, optical signals received from cell tower 160, by stamp cell 150, may be converted to high frequency RF signals for reception by the UE.
In some implementations, the passive operation of the stamp cell may be implemented using energy obtained, by the stamp cell, from either or both of the incoming radio waves or optical (laser) signals. In other implementations, the “passive” operation may refer to the fact that the stamp cell may require very little power to operate, and which may potentially be obtained from a relatively small battery or solar cell (or both) associated with the stamp cell.
Advantageously, as described above with reference to environment 100, stamp cells 150 may enable high frequency RF communications, using 5G or future generation radio technologies, via small, passive devices that can be unobtrusively placed throughout an environment. Fiber or power cabling may not be required at the deployment points of the stamp cells.
Architecture 200 may additionally include a distribution network 220 that connects cell towers 160 to packet core network 230. Distribution network 220 may be, for example, a high speed fiber distribution network. Packet core 230 may include, for example, an evolved packet core (EPC) network such as one that operates based on a 3rd Generation Partnership Project (3GPP) Wireless Communication Standard or other wireless standards. Packet core 230 may generally provide control and data transmission functions to manage the wireless connections with UEs 210.
As shown in
For a FS optical signal, the signal may need to be aimed so that the transmitted signal is received at an appropriate sensor at stamp cell downlink RX circuitry 350. In one implementation, the aiming of the signal may be manually performed during an initial provisioning or installation of stamp cell 150. Alternatively or additionally, cell tower 160 may include an aiming mechanism to aim (or fine tune the aiming of the optical signal). For example, tower downlink TX circuitry 310 may be mounted on a platform that may be rotated through one or more degrees of freedom.
Encoding/interleaving component 315 may encode the input digital signal and/or perform interleaving (e.g., to provide error correction redundancy) to obtain a baseband digital signal that is appropriate for optical transmission. The output of encoding/interleaving component 315 may be input to laser drivers 320. As shown in
Two light channels, implemented by two laser drivers 320, two light laser diodes 325, and two optical filters 330, are illustrated in
where Δf is the frequency differential and αλ is the wavelength differential and λ0 is the center wavelength.
In some implementations, the modulation of the signal may be performed using modulation techniques other than CW modulation, such as Frequency-shift keying (FSK) modulation.
Referring back to
The 60 GHz frequency differential currently corresponds to an unlicensed frequency band. Other bands, such as 40 GHz, 50 GHz, or 80 GHz may alternatively be used. In general, any band, limited only by manufacturing and technical constraints, may be used.
Although a power source is illustrated, in
As shown in
Photo diode 515 may convert the incoming optical signal (from stamp cell 150) to an electrical signal. The electrical signal may be an RF signal (e.g., bandwidth on the order of GHz) which may be filtered and decoded by filter 520 and decoding component 525. The decoding may include conversion of the RF signal to a baseband signal, which may be output as a bitstream via distribution network 220.
Antenna 555 may receive the RF signals from UE 210. In some implementations, antenna 555 and antenna 370 may be the same antenna. The electrical signals output by antenna 555 may be amplified by LNA 560. The output of LNA 560 may drive laser driver 570. Additionally, as shown in
Laser driver 570 may receive the output of LNA 560 (as affected by photo diode 565) and may drive laser diode 575 to generate an optical signal that is input to optical splitter 580. Optical splitter 580 may receive, as inputs: the output of laser diode 575 and a reflected optical signal 590. The reflected optical signal may be a reflected version of input optical signal 595. Optical splitter 580 may be used to split the output of laser diode 575 and/or the reflected optical signal to create a final plurality of uplink optical signals (e.g., the light returning to the base station may now have two components: the reflected signal which has been modulated with the second light signal modulated by the RF input radio wave).
In some implementations, as with stamp cell downlink RX circuitry 350, stamp cell uplink TX circuitry 550 may be passively powered. For example, energy from input optical signal 595 may be used to power the various components of stamp cell uplink TX circuitry 550. Alternatively or additionally, a battery may be used to provide power to stamp cell uplink TX circuitry 550. Alternatively or additionally, input optical signal 595, or another optical signal received from cell tower 560, such as a relatively high energy laser beam that is transmitted expressly for the purpose of providing power to stamp cell uplink TX circuitry 550, may be used to provide the energy needed to operate stamp cell uplink TX circuitry 550. For example, cell tower 160 may transmit an optical signal that is designed to be provided to solar cells for the generation of electrical power.
As discussed above, multiple light signals, separated by frequency spacing that correspond to high frequency RF signals, may be used in the implementation of stamp cells 150. In some examples discussed above, a 60 GHz RF carrier may generated from multiple light waves. Table I, below, provides example light wave spacing that can be used to obtain the 60 GHz carriers.
In the description above, CW modulation was generally described. In some embodiments, more complex light spacing (Lambdas) can be used to implement more complex modulation schemes. In one implementation, three light frequencies may be used to implement FSK modulation. For example, from Table I, the frequencies 197300 GHz (F1), 197240 GHz (F2), and 197180 GHz (F3) may be used. To generate FSK LoF (the low frequency), F3 and F2 may be combined (F3−F2). To generate FSK HiF (the high frequency), F3 and F1 may be combined (F3−F1).
In other implementations, additional modulation schemes, such as Quadrature Amplitude Modulation (QAM) or Orthogonal Frequency Division Modulation (OFDM) may be implemented using additional light signals. Potentially, terabit per second wireless transmissions can be achieved.
Bus 610 may include one or more communication paths that permit communication among the components of device 600. Processor 620 may include a processor, microprocessor, or processing logic that may interpret and execute instructions. Memory 630 may include any type of dynamic storage device that may store information and instructions for execution by processor 620, and/or any type of non-volatile storage device that may store information for use by processor 620.
Input component 640 may include a mechanism that permits an operator to input information to device 600, such as a keyboard, a keypad, a button, a switch, etc. Output component 650 may include a mechanism that outputs information to the operator, such as a display, a speaker, one or more light emitting diodes (“LEDs”), etc.
Communication interface 660 may include any transceiver-like mechanism that enables device 600 to communicate with other devices and/or systems. For example, communication interface 660 may include an Ethernet interface, an optical interface, a coaxial interface, or the like. Communication interface 660 may include a wireless communication device, such as an infrared (“IR”) receiver, a Bluetooth® radio, or the like. The wireless communication device may be coupled to an external device, such as a remote control, a wireless keyboard, a mobile telephone, etc. In some embodiments, device 600 may include more than one communication interface 660. For instance, device 600 may include an optical interface and an Ethernet interface.
Device 600 may perform certain operations relating to one or more processes described above. Device 600 may perform these operations in response to processor 620 executing software instructions stored in a computer-readable medium, such as memory 630. A computer-readable medium may be defined as a non-transitory memory device. A memory device may include space within a single physical memory device or spread across multiple physical memory devices. The software instructions may be read into memory 630 from another computer-readable medium or from another device. The software instructions stored in memory 630 may cause processor 620 to perform processes described herein. Alternatively, hardwired circuitry may be used in place of or in combination with software instructions to implement processes described herein. Thus, implementations described herein are not limited to any specific combination of hardware circuitry and software.
The foregoing description of implementations provides illustration and description, but is not intended to be exhaustive or to limit the possible implementations to the precise form disclosed. Modifications and variations are possible in light of the above disclosure or may be acquired from practice of the implementations.
The actual software code or specialized control hardware used to implement an embodiment is not limiting of the embodiment. Thus, the operation and behavior of the embodiment has been described without reference to the specific software code, it being understood that software and control hardware may be designed based on the description herein.
Even though particular combinations of features are recited in the claims and/or disclosed in the specification, these combinations are not intended to limit the disclosure of the possible implementations. In fact, many of these features may be combined in ways not specifically recited in the claims and/or disclosed in the specification. Although each dependent claim listed below may directly depend on only one other claim, the disclosure of the possible implementations includes each dependent claim in combination with every other claim in the claim set.
Further, while certain connections or devices are shown, in practice, additional, fewer, or different, connections or devices may be used. Furthermore, while various devices and networks are shown separately, in practice, the functionality of multiple devices may be performed by a single device, or the functionality of one device may be performed by multiple devices. Further, multiple ones of the illustrated networks may be included in a single network, or a particular network may include multiple networks. Further, while some devices are shown as communicating with a network, some such devices may be incorporated, in whole or in part, as a part of the network.
To the extent the aforementioned embodiments collect, store or employ personal information provided by individuals, it should be understood that such information shall be used in accordance with all applicable laws concerning protection of personal information. Additionally, the collection, storage and use of such information may be subject to consent of the individual to such activity, for example, through well-known “opt-in” or “opt-out” processes as may be appropriate for the situation and type of information. Storage and use of personal information may be in an appropriately secure manner reflective of the type of information, for example, through various encryption and anonymization techniques for particularly sensitive information.
Some implementations described herein may be described in conjunction with thresholds. The term “greater than” (or similar terms), as used herein to describe a relationship of a value to a threshold, may be used interchangeably with the term “greater than or equal to” (or similar terms). Similarly, the term “less than” (or similar terms), as used herein to describe a relationship of a value to a threshold, may be used interchangeably with the term “less than or equal to” (or similar terms) As used herein, “exceeding” a threshold (or similar terms) may be used interchangeably with “being greater than a threshold,” “being greater than or equal to a threshold,” “being less than a threshold,” “being less than or equal to a threshold,” or other similar terms, depending on the context in which the threshold is used.
No element, act, or instruction used in the present application should be construed as critical or essential unless explicitly described as such. An instance of the use of the term “and,” as used herein, does not necessarily preclude the interpretation that the phrase “and/or” was intended in that instance. Similarly, an instance of the use of the term “or,” as used herein, does not necessarily preclude the interpretation that the phrase “and/or” was intended in that instance. Also, as used herein, the article “a” is intended to include one or more items, and may be used interchangeably with the phrase “one or more.” Where only one item is intended, the terms “one,” “single,” “only,” or similar language is used. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.
Claims
1. A device comprising:
- an optical component that generates a reflected version of a first optical channel received by the device;
- a transmitter that generates a second optical channel based on an electrical current that has been generated based on radio frequency (“RF”) signals received by the device, the electrical current having a bandwidth corresponding to a particular frequency differential; and
- an optical splitter that transmits an output optical signal that is based on at least: the reflected version of the first optical channel, and the second optical channel,
- wherein the first and second optical channels are spaced by the same particular frequency differential as the particular frequency differential with which the electrical current corresponds.
2. The device of claim 1, further comprising:
- an antenna configured to: receive the RF signals, and convert the received RF signals to the electrical current.
3. The device of claim 2, wherein the antenna is a first antenna, the device further comprising:
- a second antenna configured to wirelessly output an RF signal, wherein the first and second antennas share a same physical structure.
4. The device of claim 1, wherein the particular frequency differential is approximately 60 gigahertz (GHz).
5. The device of claim 1, wherein the device is powered based on energy obtained from the received RF signals.
6. The device of claim 1, wherein the device implements Continuous Wave (CW) modulation or Frequency-shift keying (FSK) modulation to space the first and second optical channels by the particular frequency differential.
7. The device of claim 1, further comprising:
- an amplifier configured to amplify the electrical current, and
- a laser driver configured to receive an output of the amplifier and to drive the transmitter.
8. A method, comprising:
- reflect, by an optical component of a device, a first optical channel to generate a reflected version of the first optical channel;
- generating, by a transmitter of the device, a second optical channel based on an electrical current that has been generated based on a set of radio frequency (“RF”) signals, the electrical current having a bandwidth corresponding to a particular frequency differential; and
- transmitting, by an optical splitter of the device, an output optical signal that is based on at least: the reflected version of the first optical channel, and the second optical channel,
- wherein the first and second optical channels are spaced by the same frequency differential as the particular frequency differential with which the electrical current corresponds.
9. The method of claim 8, further comprising:
- receiving, via an antenna of the device, the RF signals; and
- converting, via the antenna of the device, the received RF signals to the electrical current.
10. The method of claim 9, wherein the antenna is a first antenna, the method further comprising:
- outputting, by a second antenna of the device that shares a same physical structure as the first antenna, an RF signal.
11. The method of claim 8, wherein the particular frequency differential is approximately 60 gigahertz (GHz).
12. The method of claim 8, further comprising:
- powering the device based on energy obtained from the received RF signals.
13. The method of claim 8, further comprising:
- implementing Continuous Wave (CW) modulation or Frequency-shift keying (FSK) modulation to space the first and second optical channels by the particular frequency differential.
14. The method of claim 8, further comprising:
- amplifying, by an amplifier of the device, the electrical current, and
- driving the transmitter of the device using an output of the amplifier.
15. A system, comprising:
- a device, comprising: an antenna configured to: receive radio frequency (“RF”) signals, and convert the received RF signals into an electrical current, the electrical current having a bandwidth corresponding to a particular frequency differential; an optical component configured to generate a reflected version of a first optical channel received by the device; a transmitter configured to generate a second optical channel based on the electrical current; and an optical splitter configured to transmit an output optical signal that is based on at least: the reflected version of the first optical channel, and the second optical channel, wherein the first and second optical channels are spaced by the same particular frequency differential as the particular frequency differential with which the electrical current corresponds.
16. The system of claim 15, wherein the antenna is a first antenna, the device further comprising:
- a second antenna configured to wirelessly output an RF signal, wherein the first and second antennas share a same physical structure.
17. The system of claim 15, wherein the frequency differential is approximately 60 gigahertz (GHz).
18. The system of claim 15, wherein the device is powered based on energy obtained from the received RF signals.
19. The system of claim 15, wherein the device implements Continuous Wave (CW) modulation or Frequency-shift keying (FSK) modulation to space the first and second optical channels by the particular frequency differential.
20. The system of claim 15, wherein the device further comprises:
- an amplifier configured to amplify the electrical current, and
- a driver configured to receive an output of the amplifier and to drive the transmitter.
Type: Application
Filed: Sep 10, 2019
Publication Date: Jan 2, 2020
Inventor: Donna L. Polehn (Mercer Island, WA)
Application Number: 16/566,389