Outer-Loop Adaptation

BACKGROUND

The following are some definitions for acronyms used throughout the industry.

DLLA—Down link link adaptation, currently the DL adaptation is divided to two parts, DL outer loop link adaptation (D-OLLA) and DL Inner loop link adaptation (D-ILLA).

The D-OLLA is responsible to update the MCS margins which are maintained per user and per MIMO mode according to the HARQ error rate observed on the specific user and a required target BLER. Once margins are updated, they are passed to the D-ILLA.

D-ILLA applies the margins on the periodic WB CQI/PMI/RI arriving from the UE and determines the MCS and MIMO combination that yields the maximum spectral efficiency. This information is passed to the PS for resource allocation and back to the PHY for transmission.

MCS—A value which indicates the modulation scheme to use in the transmission and also the effects the number of bits sent.

MCS margin—a value which depends on the HARQ responses, if a ACK is received the margin is decreased, else it is increased, the value can be also negative. Afterwards this value is decreased from the MCS value.

Step size—The value which indicates how much the margin will change after each HARQ response (ACK and NACK).

Target BLER—the receiver should target to get around ‘target BLER’ unsuccessful transmission.

MIMO—multiple-input and multiple-output, is a method for multiplying the capacity of a radio link using multiple transmission and receiving antennas to exploit multipath propagation.

SUMMARY

This invention provides outer-loop link adaptation. A way to improve the BLER value and adapt better the link to the current transmission and scenario, is to recognize this kind of scenarios, and adapt the system to work according to it.

In one embodiment, a method includes providing a service having a configuration including a Modulation Coding Scheme (MCS) margin size, a step size and a target Block Error Rate (BLER), wherein each BLER includes an adjusted step size according to a transmission type sensitivity; and adding to each Hybrid Automatic Repeat Request (HARQ) process waiting for a HARQ response, a parameter per code word that holds the used MCS value.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic diagram of an exemplary HARQ procedure, in accordance with some embodiments.

FIG. 2 is a schematic illustration of the implementation, in accordance with some embodiments.

FIG. 3 is a schematic network architecture diagram for 3G and other-G prior art networks, in accordance with some embodiments.

FIG. 4 is an enhanced eNodeB for performing the methods described herein, in accordance with some embodiments.

FIG. 5 is a coordinating server for providing services and performing methods as described herein, in accordance with some embodiments.

DETAILED DESCRIPTION

In general, during the integration process of the Enhanced DLLA ME-653, we saw that when the system is getting HARQ responses, the cells DLLA operation does not consider the following:

What type of services is used for the transmission. Currently we are using the same MCS margin parameter which indicates a value we decrease from the MCS used by the UE. For example, VOLTE call and TCP session are using the same MCS margin for changing the MCS value. Did the system already adjusted/updated the MCS value to a newer value since the message of the HARQ currently processed is replayed on.

The presently described methods and system provide a solution to this standard problem.

FIG. 1 shows a schematic diagram of an exemplary HARQ procedure, in accordance with some embodiments.

For example, message1 sent with MCS 25 value and message2 sent with the same MCS right after it, then the HARQ for message1 is received as a NACK and the MCS is adjusted according to it to 24, after it the HARQ for message2 is received as a NACK and also adjusted the MCS to 23 even though it used the previous value.

Was a transmission with a new MCS value received a NACK X times during the past X attempts with the same MCS value in the previous transmissions. For example, we used MCS 25 and got ACKed on, then we changed to MCS 26 and got NACKed on, and this scenario happens a few more times. Should we wait longer period on MCS 25 before the next time we change it to 26 again. The following questions and examples are not taken into account the DLLA implementation, causing higher BLER, and the link to be less adapted to the current state/transmission.

The DLLA implementation is very abstract and isn't tweaked for different scenarios presented above.

Solution to Problem

For each of the mentioned scenarios above an addition to the implementation is used.

To make the system consider the type of service is used, each service shall have its own configurations such as MCS margin, step size and target BLER, due to the fact that for each service we want different behavior. For example, TCP TP is sensitive to delay changes, so a faster retransmission is needed, meaning we need the adjust lower target BLER in the HARQ. Each target BLER will also have an adjusted step size according to the transmission type sensitivity. Also, by adding different MCS margin per transmission type, the HARQ responses we received on Type A transmission which is currently used will not affect Type B transmission which may be used later, where the two types have different sensitivity and QoS.

Cool off period—To make the system to take in account the MCS that was used for the current HARQ message being processed, we will add to each HARQ process which is waiting for the HARQ response a parameter per code word that holds the used MCS value, The addon for the algorithm of the outer loop will work as follows:

HARQ received, before entering the DLLA outer loop.

Check if the MCS value currently used by the system for new sent messages is equal to the MCS value used for sending the checked message via the additional parameter added per code word.

If the MCS values used are equal for at least one code word, continue with Enhanced outer loop DLLA algorithm from ME-653 only on the code words that meets the conditions above.

If number of code words HARQ received==1, update the TD MCS margin.

If ACK, reduce the MCS margin by step down.

If NACK, increase the MCS margin by step up.

If number of code words HARQ received greater than 1, update the SM MCS margin per codeword for code words that meet the condition.

If ACK, reduce the MCS margin by step down.

If NACK, increase the MCS margin by step up.

Else the MCS used is different for all code words, don't take this HARQ feedbacks into DLLA count and skip the outer loop.

- Original DLLA algorithm from ME-653
- Addon to support the MCS check

FIG. 2 is a schematic illustration of the implementation, in accordance with some embodiments.

In order to make the system handle this scenario we can add a counter that counts the number of times the MCS was changed to the current value in the last (1/StepDown*X+1/StepUp*X) HARQ responses. If the value of the counter reaches X, it means that we tried X times to use this MCS and it got NACKed each time, so we need to add a cool off period by decreasing the Stepdown by 1/X for the next 1/StepDown transmissions. By doing this we will delay the changing of the MCS by X.

FIG. 3 is a schematic network architecture diagram for 3G and other-G prior art networks, in accordance with some embodiments. The diagram shows a plurality of “Gs,” including 2G, 3G, 4G, 5G and Wi-Fi. 2G is represented by GERAN 301, which includes a 2G device 301a, BTS 301b, and BSC 301c. 3G is represented by UTRAN 302, which includes a 3G UE 302a, nodeB 302b, RNC 302c, and femto gateway (FGW, which in 3GPP namespace is also known as a Home nodeB Gateway or HNBGW) 302d. 4G is represented by EUTRAN or E-RAN 303, which includes an LTE UE 303a and LTE eNodeB 303b. Wi-Fi is represented by Wi-Fi access network 304, which includes a trusted Wi-Fi access point 304c and an untrusted Wi-Fi access point 304d. The Wi-Fi devices 304a and 304b may access either AP 304c or 304d. In the current network architecture, each “G” has a core network. 2G circuit core network 305 includes a 2G MSC/VLR; 2G/3G packet core network 306 includes an SGSN/GGSN (for EDGE or UMTS packet traffic); 3G circuit core 307 includes a 3G MSC/VLR; 4G circuit core 308 includes an evolved packet core (EPC); and in some embodiments the Wi-Fi access network may be connected via an ePDG/TTG using S2a/S2b. Each of these nodes are connected via a number of different protocols and interfaces, as shown, to other, non-“G”-specific network nodes, such as the SCP 330, the SMSC 331, PCRF 332, HLR/HSS 333, Authentication, Authorization, and Accounting server (AAA) 334, and IP Multimedia Subsystem (IMS) 335. An HeMS/AAA 336 is present in some cases for use by the 3G UTRAN. The diagram is used to indicate schematically the basic functions of each network as known to one of skill in the art, and is not intended to be exhaustive. For example, 5G core 317 is shown using a single interface to 5G access 316, although in some cases 5G access can be supported using dual connectivity or via a non-standalone deployment architecture.

Noteworthy is that the RANs 301, 302, 303, 304 and 336 rely on specialized core networks 305, 306, 307, 308, 309, 337 but share essential management databases 330, 331, 332, 333, 334, 335, 338. More specifically, for the 2G GERAN, a BSC 301c is required for Abis compatibility with BTS 301b, while for the 3G UTRAN, an RNC 302c is required for Iub compatibility and an FGW 302d is required for Iuh compatibility. These core network functions are separate because each RAT uses different methods and techniques. On the right side of the diagram are disparate functions that are shared by each of the separate RAT core networks. These shared functions include, e.g., PCRF policy functions, AAA authentication functions, and the like. Letters on the lines indicate well-defined interfaces and protocols for communication between the identified nodes.

The system may include 5G equipment. 5G networks are digital cellular networks, in which the service area covered by providers is divided into a collection of small geographical areas called cells. Analog signals representing sounds and images are digitized in the phone, converted by an analog to digital converter and transmitted as a stream of bits. All the 5G wireless devices in a cell communicate by radio waves with a local antenna array and low power automated transceiver (transmitter and receiver) in the cell, over frequency channels assigned by the transceiver from a common pool of frequencies, which are reused in geographically separated cells. The local antennas are connected with the telephone network and the Internet by a high bandwidth optical fiber or wireless backhaul connection.

5G uses millimeter waves which have shorter range than microwaves, therefore the cells are limited to smaller size. Millimeter wave antennas are smaller than the large antennas used in previous cellular networks. They are only a few inches (several centimeters) long. Another technique used for increasing the data rate is massive MIMO (multiple-input multiple-output). Each cell will have multiple antennas communicating with the wireless device, received by multiple antennas in the device, thus multiple bitstreams of data will be transmitted simultaneously, in parallel. In a technique called beamforming the base station computer will continuously calculate the best route for radio waves to reach each wireless device, and will organize multiple antennas to work together as phased arrays to create beams of millimeter waves to reach the device.

FIG. 4 is an enhanced eNodeB for performing the methods described herein, in accordance with some embodiments. eNodeB 400 may include processor 402, processor memory 404 in communication with the processor, baseband processor 406, and baseband processor memory 408 in communication with the baseband processor. Mesh network node 400 may also include first radio transceiver 412 and second radio transceiver 414, internal universal serial bus (USB) port 416, and subscriber information module card (SIM card) 418 coupled to USB port 416. In some embodiments, the second radio transceiver 414 itself may be coupled to USB port 416, and communications from the baseband processor may be passed through USB port 416. The second radio transceiver may be used for wirelessly backhauling eNodeB 400.

Processor 402 and baseband processor 406 are in communication with one another. Processor 402 may perform routing functions, and may determine if/when a switch in network configuration is needed. Baseband processor 406 may generate and receive radio signals for both radio transceivers 412 and 414, based on instructions from processor 402. In some embodiments, processors 402 and 406 may be on the same physical logic board. In other embodiments, they may be on separate logic boards.

Processor 402 may identify the appropriate network configuration, and may perform routing of packets from one network interface to another accordingly. Processor 402 may use memory 404, in particular to store a routing table to be used for routing packets. Baseband processor 406 may perform operations to generate the radio frequency signals for transmission or retransmission by both transceivers 410 and 412. Baseband processor 406 may also perform operations to decode signals received by transceivers 412 and 414. Baseband processor 406 may use memory 408 to perform these tasks.

The first radio transceiver 412 may be a radio transceiver capable of providing LTE eNodeB functionality, and may be capable of higher power and multi-channel OFDMA. The second radio transceiver 414 may be a radio transceiver capable of providing LTE UE functionality. Both transceivers 412 and 414 may be capable of receiving and transmitting on one or more LTE bands. In some embodiments, either or both of transceivers 412 and 414 may be capable of providing both LTE eNodeB and LTE UE functionality. Transceiver 412 may be coupled to processor 402 via a Peripheral Component Interconnect-Express (PCI-E) bus, and/or via a daughtercard. As transceiver 414 is for providing LTE UE functionality, in effect emulating a user equipment, it may be connected via the same or different PCI-E bus, or by a USB bus, and may also be coupled to SIM card 418. First transceiver 412 may be coupled to first radio frequency (RF) chain (filter, amplifier, antenna) 422, and second transceiver 414 may be coupled to second RF chain (filter, amplifier, antenna) 424.

SIM card 418 may provide information required for authenticating the simulated UE to the evolved packet core (EPC). When no access to an operator EPC is available, a local EPC may be used, or another local EPC on the network may be used. This information may be stored within the SIM card, and may include one or more of an international mobile equipment identity (IMEI), international mobile subscriber identity (IMSI), or other parameter needed to identify a UE. Special parameters may also be stored in the SIM card or provided by the processor during processing to identify to a target eNodeB that device 400 is not an ordinary UE but instead is a special UE for providing backhaul to device 400.

Wired backhaul or wireless backhaul may be used. Wired backhaul may be an Ethernet-based backhaul (including Gigabit Ethernet), or a fiber-optic backhaul connection, or a cable-based backhaul connection, in some embodiments. Additionally, wireless backhaul may be provided in addition to wireless transceivers 412 and 414, which may be Wi-Fi 802.11a/b/g/n/ac/ad/ah, Bluetooth, ZigBee, microwave (including line-of-sight microwave), or another wireless backhaul connection. Any of the wired and wireless connections described herein may be used flexibly for either access (providing a network connection to UEs) or backhaul (providing a mesh link or providing a link to a gateway or core network), according to identified network conditions and needs, and may be under the control of processor 402 for reconfiguration.

A GPS module 430 may also be included, and may be in communication with a GPS antenna 432 for providing GPS coordinates, as described herein. When mounted in a vehicle, the GPS antenna may be located on the exterior of the vehicle pointing upward, for receiving signals from overhead without being blocked by the bulk of the vehicle or the skin of the vehicle. Automatic neighbor relations (ANR) module 432 may also be present and may run on processor 402 or on another processor, or may be located within another device, according to the methods and procedures described herein.

Other elements and/or modules may also be included, such as a home eNodeB, a local gateway (LGW), a self-organizing network (SON) module, or another module. Additional radio amplifiers, radio transceivers and/or wired network connections may also be included.

FIG. 5 is a coordinating server for providing services and performing methods as described herein, in accordance with some embodiments. Coordinating server 500 includes processor 502 and memory 504, which are configured to provide the functions described herein. Also present are radio access network coordination/routing (RAN Coordination and routing) module 506, including ANR module 506a, RAN configuration module 508, and RAN proxying module 510. The ANR module 506a may perform the ANR tracking, PCI disambiguation, ECGI requesting, and GPS coalescing and tracking as described herein, in coordination with RAN coordination module 506 (e.g., for requesting ECGIs, etc.). In some embodiments, coordinating server 500 may coordinate multiple RANs using coordination module 506. In some embodiments, coordination server may also provide proxying, routing virtualization and RAN virtualization, via modules 510 and 508. In some embodiments, a downstream network interface 512 is provided for interfacing with the RANs, which may be a radio interface (e.g., LTE), and an upstream network interface 514 is provided for interfacing with the core network, which may be either a radio interface (e.g., LTE) or a wired interface (e.g., Ethernet).

Coordinator 500 includes local evolved packet core (EPC) module 520, for authenticating users, storing and caching priority profile information, and performing other EPC-dependent functions when no backhaul link is available. Local EPC 520 may include local HSS 522, local MME 524, local SGW 526, and local PGW 528, as well as other modules. Local EPC 520 may incorporate these modules as software modules, processes, or containers. Local EPC 520 may alternatively incorporate these modules as a small number of monolithic software processes. Modules 506, 508, 510 and local EPC 520 may each run on processor 502 or on another processor, or may be located within another device.

In any of the scenarios described herein, where processing may be performed at the cell, the processing may also be performed in coordination with a cloud coordination server. A mesh node may be an eNodeB. An eNodeB may be in communication with the cloud coordination server via an X2 protocol connection, or another connection. The eNodeB may perform inter-cell coordination via the cloud communication server when other cells are in communication with the cloud coordination server. The eNodeB may communicate with the cloud coordination server to determine whether the UE has the ability to support a handover to Wi-Fi, e.g., in a heterogeneous network.

Although the methods above are described as separate embodiments, one of skill in the art would understand that it would be possible and desirable to combine several of the above methods into a single embodiment, or to combine disparate methods into a single embodiment. For example, all of the above methods could be combined. In the scenarios where multiple embodiments are described, the methods could be combined in sequential order, or in various orders as necessary.

Although the above systems and methods for providing interference mitigation are described in reference to the Long Term Evolution (LTE) standard, one of skill in the art would understand that these systems and methods could be adapted for use with other wireless standards or versions thereof. The inventors have understood and appreciated that the present disclosure could be used in conjunction with various network architectures and technologies. Wherever a 4G technology is described, the inventors have understood that other RATs have similar equivalents, such as a gNodeB for 5G equivalent of eNB. Wherever an MME is described, the MME could be a 3G RNC or a 5G AMF/SMF. Additionally, wherever an MME is described, any other node in the core network could be managed in much the same way or in an equivalent or analogous way, for example, multiple connections to 4G EPC PGWs or SGWs, or any other node for any other RAT, could be periodically evaluated for health and otherwise monitored, and the other aspects of the present disclosure could be made to apply, in a way that would be understood by one having skill in the art.

Additionally, the inventors have understood and appreciated that it is advantageous to perform certain functions at a coordination server, such as the Parallel Wireless HetNet Gateway, which performs virtualization of the RAN towards the core and vice versa, so that the core functions may be statefully proxied through the coordination server to enable the RAN to have reduced complexity. Therefore, at least four scenarios are described: (1) the selection of an MME or core node at the base station; (2) the selection of an MME or core node at a coordinating server such as a virtual radio network controller gateway (VRNCGW); (3) the selection of an MME or core node at the base station that is connected to a 5G-capable core network (either a 5G core network in a 5G standalone configuration, or a 4G core network in 5G non-standalone configuration); (4) the selection of an MME or core node at a coordinating server that is connected to a 5G-capable core network (either 5G SA or NSA). In some embodiments, the core network RAT is obscured or virtualized towards the RAN such that the coordination server and not the base station is performing the functions described herein, e.g., the health management functions, to ensure that the RAN is always connected to an appropriate core network node. Different protocols other than S1AP, or the same protocol, could be used, in some embodiments.

In some embodiments, the base stations described herein may support Wi-Fi air interfaces, which may include one or more of IEEE 802.11a/b/g/n/ac/af/p/h. In some embodiments, the base stations described herein may support IEEE 802.16 (WiMAX), to LTE transmissions in unlicensed frequency bands (e.g., LTE-U, Licensed Access or LA-LTE), to LTE transmissions using dynamic spectrum access (DSA), to radio transceivers for ZigBee, Bluetooth, or other radio frequency protocols, or other air interfaces.

In some embodiments, the software needed for implementing the methods and procedures described herein may be implemented in a high level procedural or an object-oriented language such as C, C++, C#, Python, Java, or Perl. The software may also be implemented in assembly language if desired. Packet processing implemented in a network device can include any processing determined by the context. For example, packet processing may involve high-level data link control (HDLC) framing, header compression, and/or encryption. In some embodiments, software that, when executed, causes a device to perform the methods described herein may be stored on a computer-readable medium such as read-only memory (ROM), programmable-read-only memory (PROM), electrically erasable programmable-read-only memory (EEPROM), flash memory, or a magnetic disk that is readable by a general or special purpose-processing unit to perform the processes described in this document. The processors can include any microprocessor (single or multiple core), system on chip (SoC), microcontroller, digital signal processor (DSP), graphics processing unit (GPU), or any other integrated circuit capable of processing instructions such as an x86 microprocessor.

In some embodiments, the radio transceivers described herein may be base stations compatible with a Long Term Evolution (LTE) radio transmission protocol or air interface. The LTE-compatible base stations may be eNodeBs. In addition to supporting the LTE protocol, the base stations may also support other air interfaces, such as UMTS/HSPA, CDMA/CDMA2000, GSM/EDGE, GPRS, EVDO, 2G, 3G, 5G, TDD, or other air interfaces used for mobile telephony.

The foregoing discussion discloses and describes merely exemplary embodiments of the present invention. In some embodiments, software that, when executed, causes a device to perform the methods described herein may be stored on a computer-readable medium such as a computer memory storage device, a hard disk, a flash drive, an optical disc, or the like. As will be understood by those skilled in the art, the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. For example, wireless network topology can also apply to wired networks, optical networks, and the like. The methods may apply to LTE-compatible networks, to UMTS-compatible networks, or to networks for additional protocols that utilize radio frequency data transmission. Various components in the devices described herein may be added, removed, split across different devices, combined onto a single device, or substituted with those having the same or similar functionality.

Although the present disclosure has been described and illustrated in the foregoing example embodiments, it is understood that the present disclosure has been made only by way of example, and that numerous changes in the details of implementation of the disclosure may be made without departing from the spirit and scope of the disclosure, which is limited only by the claims which follow. Various components in the devices described herein may be added, removed, or substituted with those having the same or similar functionality. Various steps as described in the figures and specification may be added or removed from the processes described herein, and the steps described may be performed in an alternative order, consistent with the spirit of the invention. Features of one embodiment may be used in another embodiment.

Outer-Loop Adaptation

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CROSS-REFERENCE TO RELATED APPLICATIONS

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