WO2024144623A1

WO2024144623A1 - A network controlled repeater having increased spatial degrees of freedom

Info

Publication number: WO2024144623A1
Application number: PCT/TR2023/051455
Authority: WO
Inventors: Musab Mahmoud Abd Alkareem ALAYASRA; Muhammad Bilal JANJUA; Fatih KILINC; Huseyin Arslan
Original assignee: Ulak Haberlesme Anonim Sirketi
Priority date: 2022-12-31
Filing date: 2023-12-04
Publication date: 2024-07-04

Abstract

The invention relates to a system (10) comprising at least a transmitting point (200) which is suitable for cellular communication for multiple user equipment (300) and comprises an input (210) for receiving input signals that are dedicated to be sent to said user equipment and a baseband processing unit (210) for transforming the transmission signals received from said input (210) into transmission layers (400) in digital domain; and at least one network controlled repeater (100), characterized in that said transmitting point (200) comprises multiple RF chains (240) for shifting transmission layers to the predetermined frequency bands so as to be in non-overlapping frequency bands for each user equipment (300), and a beam and it further comprises a beamforming unit (250) and antenna units (260) for beamforming and transmitting frequency shifted transmission layers (400), and that the network controlled repeater (100) comprises a plurality of receiver antenna units (110) and receiver beamforming circuit (120) for receiving directional transmission layers (400), multiple repeater RF chains (150) for filtering the transmission layer (400) in the frequency band assigned to it, amplifying the filtered transmission layer (400) and converting the amplified transmission layers (400) to a network operating frequency, and transmitter beamforming circuits (140) connected to each repeater RF chain (150), for spatially multiplexing the transmission layers converted to the network operating frequency and transmitting them to the user equipment (300).

Description

A NETWORK CONTROLLED REPEATER HAVING INCREASED SPATIAL DEGREES OF FREEDOM

TECHNICAL FIELD

Present invention relates to a system comprising at least a transmitting point, in particular a base station, and network controlled repeater; repeater thereof and method thereof.

BACKGROUND

Next-generation wireless communication systems may include a 5G core network and a 5G radio access network (RAN), such as a New Radio (NR)-RAN. The NR-RAN supports communication via one or more cells. For example, a wireless communication device such as a user equipment (UE) may access a first cell of a first network access node such as a base station (gNB: g node b) and/or access a second cell of a second network access node. In some instances, a repeater device may be located between the UE and a network access node. The repeater device may relay traffic and control between the UE and network access node in both the uplink and downlink directions.

A type of repeater is known as network-controlled repeater (NCR) or as smart repeater. Network-controlled repeaters adds diversity gain to the system by sending same RF signal over multiple ports, or beams, to users. It amplifies and transmits a signal received from base station over the created ports by means of analogue beamforming. This architecture of such repeaters supports diversity; however, it cannot perform spatial multiplexing for users.

Current network-controlled repeaters (NCRs) are designed to have one amplification line. There are two analogue beamforming circuits at both base station and user sides, which are used to form beams for an increased transmission gain. Both circuits are connected to one amplifier that amplifies the received signal to be transmitted at the other side. As all processing at NCR is in the RF domain, with such design only one transmission layer is utilized by NCR. Therefore, NCR with multiple beamforming circuits can only provide diversity gain and thus suppresses spatial degrees of freedom between base station and users to one.

All the problems mentioned above have made it necessary to make an innovation in the relevant technical field as a result.

BRIEF DESCRIPTION OF THE INVENTION

The present invention relates to a network controlled repeater, system and a method to eliminate the above-mentioned disadvantages and bring new advantages to the relevant technical field.

An object of the invention is to increase spatial degrees of freedom of network controlled repeaters.

Another object of the invention is allow network controlled repeaters to transmit signals to multiple users at the same time with reduced interference.

In order to realize the abovementioned objects and the objects which are to be deducted from the detailed description below, the present invention relates to a system comprising at least a transmitting point and at least a network controlled repeater suitable for receiving signal from said transmitting point. Accordingly, transmitting point is configured to receive multiple transmission layers to be sent to different users; transmitting point is configured to multiplex said transmission layers over frequency and transmit to network controlled repeater; network controlled repeater comprises multiple repeater RF chains each dedicated to process one of the transmission layers wherein transmission layers are filtered and their frequency is transitioned to a frequency band that a designated user equipment can receive and by beamforming circuits transmission layers mapped into ports; network controlled repeater further configured to realize beamforming to spatially multiplexed transmission layers and transmit them in the specific directions to dedicated users. Thus, network controlled repeater can transmit multiple transmission layers to multiple user equipment at the same time, increasing spatial degree of freedom of the repeater and the cell.

The present invention also is above mentioned network controlled repeater. The present invention also is above mentioned transmitting point capable of transmitting transmission layers multiplexed over frequency.

The present invention is also a method realized by the system for transmitting input signals to user equipment

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a drawing illustrating schematic view of the system.

Figure 2 is a drawing illustrating schematic view of transmitting point.

Figure 3 is a drawing illustrating schematic view of network controlled repeater.

Figure 4a is a space-frequency graphic showing multiplexed transmission layers over frequency.

Figure 4b is a space-frequency graphic showing multiplexed transmission layers over space.

DETAILED DESCRIPTION OF THE INVENTION

In this detailed description, invention is explained with examples, that do not have any limiting effect, are provided only for a better understanding of the subject.

The invention is a network controlled repeater (100), the invention is also a transmitting point (200) suitable for operating with said network controlled repeater (100), a system (10) comprising the network controlled repeater (100) and said transmitting point (200) and transmission method thereof.

Transmitting point (200) mentioned here may be a base station, an access point (AP), a 5g base station that is gNodeB (gNB) or a satellite. Referring to figure 1 , present invention is a system (10) comprising at least transmitting point (200) that provides cellular communication for user equipment (300) and further comprising at least a network controlled repeater (100). T ransmitting point (200) receives input signals to be transmitted to multiple user equipment (300). Transmitting point (200) divides input signals into digital transmission layers (400) and then applies frequency shifting to said transmission layers (400) in such way that transmission layers (400) are multiplexed over frequency. Transmitting point (200) further applies beamforming processes to multiplexed input signals and transmits them. In a possible embodiment, transmitting point (200) spatially multiplexes transmission layers (400). For this embodiment multiple strong reflections estimated between network controlled repeater (100) and transmitting point (200). In this embodiment, network controlled repeater (100) has receiving beamforming circuits each directed towards a corresponding angle requested by network controller (not shown in the figures).

Network controlled repeater (100) receives transmitted input signals and processes them separately at the same time by separate signal processing circuits provided for each band. Network controlled repeater (100) then multiplexes received input signals over space. Network controlled repeater (100), uses beamforming to create ports for user equipment (300) and transmits spatially multiplexed signals. Thus, multiple users may receive their input signals at the same time, over repeaters.

Transmitting point (200) and network controlled repeaters (100) are configured to have a line of sight (Los) link. This configuration may be realized by placing network controlled repeater (100) on a predetermined locations that have line of sight. Thus, there is a strong LoS link between transmitting point (200) and NCR with an abundance of frequency bands. Since the LoS beam is narrower and propagation losses are larger at higher operating frequencies, the signal transmitted over this beam does not interfere with other users or other technologies in the vicinity. Consequently, large bandwidths in licensed and unlicensed bands might be exploited for the transmitting point (200) link to NCR.

In a possible embodiment of the invention, multipath components (not shown in the figures) may be provided between network controlled repeater (100) and transmitting point (200). Said multipath components may be reflecting components that reflect signal carrying rays in a multipath link between network controlled repeater (100) and transmitting point. In an embodiment multipath component may be a passive reflector suitable for reflecting signal carrying beams.

Referring to figure 2, transmitting point (200) comprises an input (210) for receiving input signals that are dedicated to be sent to user equipment (300). Input (210) may be configured to receive multiple input signals for multiple user equipment (300) at the same time. Input signals are in form of input data streams. Transmitting point 200) comprises a baseband processing circuit connected to input (210). Baseband processing unit (220), processes input signals and transform them into transmission layers (400) in digital domain. Transmitting point (200) comprises transmitting point (200) RF chains (240) connected to baseband processing unit (220). RF chains (240) are well-known to be utilized in transmitting points. In the present invention however, transmitting point (200) RF chain (240) is configured to shift transmission layers (400) to a specific frequency band. Thus, multiple transmission layers (400) are multiplexed over frequency. Fig. 4a illustrates an example of transmission layers (400) multiplexed over frequency. A first transmission layer (410), a second transmission layer (420) and a third transmission layer (430) are shifted so they are at different frequency bands. For instance first transmission layer (410) may be in a first frequency band, second transmission layer (420) in a second frequency band and third transmission layer (430) may be in a third frequency band where frequency bands are not overlapping.

Transmitting point (200) further comprises a beamforming unit (250) and antenna units (260) for beamforming and transmitting frequency shifted transmission layers (400).

Transmitting point (200) comprises a TP control unit (230), that communicates with input signal source or network controlled repeater (100). TP Control unit (230), may comprise microprocessor, CPU, or GPU or any kind of suitable processor. TP Control unit (230) is configured to transmit signal to network controlled repeater (100) about transmission layers (400) and beamforming, so it can receive and relay transmitted transmission layers (400).

Referring to figure 5, network controlled repeater (100) comprises plurality of receiver antenna units (1 10) and receiver beamforming circuit (120) for receiving directional transmission layers (400) transmitted from transmitting point. Number of receiver antenna unit (1 10) and receiver beamforming circuits (120) can be equal to transmission layers (400) being transmitted from transmitting point (200).

Antenna units mentioned in this description may have antennas and other components in order antennas to receive and transmit signals. Beamforming circuits may comprise components that are well known in the art that is used for beamforming.

Network controlled repeater (100) comprises plurality of repeater RF chain (150). Each repeater RF chain (150) filters frequency band assigned to it, amplifies filtered transmission layer (400) and converts transmission layers (400) to a network operating frequency. Network operating frequency is the frequency that user equipment (300) receive signal. Each repeater RF chain (150) may comprise a filtering element (151 ), an amplification element (152) and a mixing element (153).

Network controlled repeater (100) further comprises transmitter beamforming circuits (140) connected to each repeater RF chains (150). So each transmission layer (400) has its receiver beamforming circuit (120), repeater RF chain (150), transmitter beamforming circuit (140). Thus, each transmission layer (400) sent to NCR via LoS established between transmitting point (200) and NCR in frequency multiplexed manner and each transmission layer (400) is relayed to user equipment (300) in a spatially multiplexed manner. Spatially multiplexed transmission layers (400) are shown in figure 4b. Their frequency is shifted to frequency band that user equipment (300) use, and spatially multiplexed. For instance, first transmission layer (410) is transmitted using a first beam direction in first frequency band; second transmission layer (420) is transmitted using a second beam direction in first frequency band and third transmission layer (430) is transmitted using a third beam direction in first frequency.

Network controlled repeater (100) comprises a control unit (160) which is configured to control beamforming circuits, and components in repeater RF chain (150). Control unit (160), is configured to receive commands and signals from TP control unit (230).

Before transmitting input signals to network controlled repeater (100) a physical transmission method is realized by said system (10). The method comprise following steps: In a possible embodiment, aligning LoS between transmitting point (200) and NCR. In this step, LoS between transmitting point (200) and NCR may be aligned through alternation of receiver/transmitter antenna orientation.

Realizing a channel estimation on transmitting channel between user equipment (300) and NCR (h2). This step can be realized with any channel estimation algorithm. Thus, channel information at the transmitting point (200) side is acquired. There is no need to estimate channel between NCR and transmitting point (200) (hi ) as only LoS link is adopted there. Based on channel information between user equipment (300) and NCR, transmitting point (200) follows any hybrid beamforming algorithm as if it has directly h2 connection with the users.

This step outputs two matrices: baseband matrix and analogue beamforming matrix w referring to figure 4a and 4b. Unlike conventional hybrid beamforming, w is not used at the transmitting point (200) side, but at NCR side as the transmission layers (400) at transmitting point are transmitted over different frequencies and not different ports (or beams) from transmitting point to NCR.

- Selecting NCR ports. After channel estimation, NCR ports are selected to relay information. Aforementioned ports define beam direction and beamforming circuits that is selected for realizing beamforming in that direction.

- Sending NCR informing signal relating to selected ports.

In a possible embodiment, Informing NCR relating to frequencies that transmission will be conducted.

Designing baseband precoding.

- Starting transmission.

The system (10) realizes following steps during transmission:

By baseband processing unit (220) precoding input signals (data streams). In this step, baseband processing unit (220) precedes input signals using pre-designed baseband precoding. Thus, digital transmission layers (400) are generated.

- Transitioning frequency of transition layers in such way that they are multiplexed over frequency. Transmission layers (400) are placed in different frequency bands to be transmitted through LoS link.

Transmitting transmission layers (400) over LoS to NCR. Receiving transmission layer (400) by receiver antenna units (110) and receiver antenna circuits.

By each repeater RF chain (150), filtering received transmission layers (400) using their assigned band. Thus, every RF chain (240) filters transmission layer (400) it has assigned to.

By each repeater RF chain (150), transitioning frequency of filtered transmission layers (400) so that transmission layers (400) are placed to frequency bands that user equipment (300) can receive.

Sending transmission layers (400) over transmitter beamforming circuits (140) and transmitter antenna units (130) to user equipment (300). Transmission layers (400) are spatially multiplexed and orthogonality is realized between users.

Since transmission layers (400) are directed by beamforming, each user receives its directed transmission layer (400) without interference.

If the channel between transmitter and repeater has reflections that can be separated by beams at both transmitter and repeater sides, then transmission layers might be multiplexed over those reflections instead of frequency (or may be both). In this case receive beamforming circuits at the repeater will direct their beams toward the corresponding directions of their transmission layers.

Instead of multiplexing transmission layers (400) in frequency domain, user’s data might be multiplexed directly. However, for spatial multiplexing at h2 to work, users must be separable by analogue beamforming only. This might be the case when users are in LoS with NCR, and they are far enough from each other so that different beams can select them orthogonally.

In the network, NCRs might be placed in such a way that one or multiple NCRs can act as active scatterers for another NCR. transmitting point, in such setup, will send different transmission layers (400) over different beams to different NCRs that are not serving users yet. In their turn, each of these NCRs direct the received transmission layer (400) toward the targeted NCR. The targeted NCR receives multiple transmission layers (400) over different beams from different directions at the same operating frequency and direct them to users through h2 by its analogue beamforming as instructed by transmitting point. Another case to consider also is multiple coordinated transmitting point s connected to one NCR. Similar to the previous case with multiple NCRs, different transmission layers (400) might be sent from coordinated transmitting points to one NCR so it can serve its users spatially. It is important to mention here that coordinated transmitting points might serve multiple NCRs with different transmission layers (400) at the same time. In other words, base stations and NCRs work jointly to enable spatial multiplexing at different NCRs with their corresponding users. The scope of protection of the invention is specified in the attached claims and cannot be limited to those explained for sampling purposes in this detailed description. It is evident that a person skilled in the art may exhibit similar embodiments in light of the above-mentioned facts without drifting apart from the main theme of the invention.

REFERENCE NUMBERS GIVEN IN THE FIGURE

10 System

100 Network Controlled Repeater

110 Receiver antenna unit

120 Receiver beamforming circuit

130 Transmitter antenna unit

140 Transmitter beamforming circuit

150 Repeater RF chain

151 Filtering element

152 Amplification element

153 Mixing element

160 Control unit

200 transmitting point

210 Input

220 Baseband processing unit

230 TP control unit

240 RF chain

250 Beamforming unit

260 Antenna unit

300 User equipment

400 Transmission layer

410 First transmission layer

420 Second transmission layer

430 Third transmission layer

Claims

1 . A system (10) comprising at least a transmitting point (200) which is suitable for cellular communication for multiple user equipment (300) and comprises an input (210) for receiving input signals that are dedicated to be sent to said user equipment and a baseband processing unit (210) for transforming the transmission signals received from said input (210) into transmission layers (400) in digital domain; and at least one network controlled repeater (100), characterized in that said transmitting point (200) comprises multiple RF chains (240) for shifting transmission layers to the predetermined frequency bands so as to be in non-overlapping frequency bands for each user equipment (300), and a beam and it further comprises a beamforming unit (250) and antenna units (260) for beamforming and transmitting frequency shifted transmission layers (400); and that the network controlled repeater (100) comprises a plurality of receiver antenna units (1 10) and receiver beamforming circuit (120) for receiving directional transmission layers (400), multiple repeater RF chains (150) for filtering the transmission layer (400) in the frequency band assigned to it, amplifying the filtered transmission layer (400) and converting the amplified transmission layers (400) to a network operating frequency, and transmitter beamforming circuits (140) connected to each repeater RF chain (150), for spatially multiplexing the transmission layers converted to the network operating frequency and transmitting them to the user equipment (300).

2. A system (10) according to claim 1 , characterized in that the transmitting points (200) comprise receiving beamforming circuits each directed towards a corresponding angle requested by network controller and are configured to spatially multiplex the transmission layers.

3. A system (10) according to claim 1 , characterized in that it comprises reflecting multipath components that reflect signal carrying rays in a multipath link between network controlled repeater (100) and transmitting point (200) between network controlled repeater (100) and transmitting point.

4. A system (10) according to claim 3, characterized in that said multipath components are passive reflectors.

5. A method carried out by a system (10) comprising at least a transmitting point (200) which is suitable for cellular communication for multiple user equipment (300) and comprises an input (210) for receiving input signals that are dedicated to be sent to said user equipment and a baseband processing unit (210) for transforming the transmission signals received from said input (210) into transmission layers (400) in digital domain; and at least one network controlled repeater (100), characterized in that it comprises the steps of: precoding the input signals by the baseband processing unit (220) and generating the digital transmission layers (400), arranging the transition layers in such way that they are multiplexed over frequency,

- transmitting transmission layers (400) over LoS to the network controlled repeater (100),

- receiving transmission layer (400) by receiver antenna units (110) and receiver beamforming circuits (120) of the network controlled repeater (100), filtering the received transmission layers (400) in the assigned bands by each repeater RF chain (150) of the network controlled repeater (100), placing the transmission layers (400) in the frequency bands that the user equipment (300) can receive by changing the transitioning frequency of filtered transmission layers (400), by each repeater RF chain (150), sending transmission layers (400) over transmitter beamforming circuits (140) and transmitter antenna units (130) to user equipment (300).

6. A method according to claim 5, characterized in that said multipath components are passive reflectors.