Claims:1. A system for mitigating common-site interference between co-located radios, the system comprising:
a plurality of first radios (102-1, 102-2…102-n) located at a first site, and wherein the plurality of the first radios (102-1, 102-2…102-n) are communicatively coupled to an ethernet hub (106), and wherein one of the plurality of first radios (102-1) is configured to generate and transmit timing reference ethernet packets to rest of the plurality of the first radios through the ethernet hub (106); and
a plurality of second radios(104-1, 104-2….104-n) communicatively coupled to the plurality of first radios (102-1, 102-2…102-n),
and wherein the rest of the plurality of first radios (102-2…102-n) are configured to transmit data to the plurality of second radios (104-1, 104-2…104-n),based on the timing reference ethernet packets, for mitigating the common site interference.
2. The system as claimed in the claim 1, wherein the plurality of the first radios (102-1, 102-2….102-n) are communicatively coupled with the ethernet hub (106) using an ethernet bus.
3. The system as claimed in the claim 2, wherein the plurality of the first radios (102-1, 102-2…102-n) are communicatively coupled with the ethernet bus through their respective control ethernet interface (112-1, 112-2….112-n).
4. The system as claimed in the claim 1, wherein the plurality of first radios (102-1, 102-2…102-n) are master radios.
5. The system as claimed in the claim 1, wherein the plurality of second radios (104-1, 104-2…104-n) are slave radios.
6. The system as claimed in claim 1, wherein the one of the plurality of the first radios (102-1) is configured to generate an internal reference clock, and transmit the timing reference ethernet packets on valid internal reference clock transition, and wherein the valid internal reference clock transition is configured on the basis of the internal reference clock stability.
7. The system as claimed in claim 5, wherein the system comprises a timing master (102-1) configured to broadcast timing reference ethernet packet at predefined interval of time, and wherein the predefined interval of time is an integral multiple of time slot.
8. The system as claimed in claim 7, wherein the rest of the plurality of the first radios (102-2…102-n) are configured to be aligned to the internal reference clock of timing master, and the plurality of second radios (104-1, 104-2….104-n) have negated version of internal reference clock of respective plurality of master radios.
9. The system as claimed in claim 8, wherein the plurality of first radios (102-1, 102-2….102-n) are communicatively coupled with a data hub (110), through a data interface (108).
10. The system as claimed in claim 1, wherein the timing reference ethernet packets comprises an information related to timing of transmission and reception of the plurality of first radios (102-1, 102-2…102-n).
11. The system as claimed in claim 1, wherein the plurality of first radios (102-2…102-n) are configured to transmit data to the plurality of second radios (104-1, 104-2….104-n) with respect to respective internal reference clocks post alignment with the timing master (102-1).
12. The system as claimed in claim 1, wherein the plurality of first radios (102-2…102-n) and the plurality of second radios (104-1, 104-2….104-n) are half duplex radios.
, Description:TECHNICAL FIELD
[0001] The present disclosure relates to the field of co-location of the half duplex radios. More particularly the present disclosure relates to a system for mitigating co-site/common-site interference between the radios when positioned in close proximity to each other.

BACKGROUND
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] Radio frequency (RF) co-site (common-site) interference occurs when two or more RF systems, located in same site, affect one another negatively. This normally occurs when two or more RF systems are operating physically close to one another (within several feet to hundreds of feet) and they are operating in such a way that one of the system transmitters negatively impacts one or more system receivers. RF systems mostly use time division duplex (TDD) for realizing full duplex communication over a half-duplex communication links. A time division duplex (TDD) is a duplex communication links where uplink is separated from downlink by the allocation of different time slots in the same frequency band. A time slot is a predefined amount of time during which a radio either transmits or receives a single RF packet. The RF packet is the information which is exchanged between communicatively coupled Master and Slave pair through antennas.The system comprises of two types of RF packets namely “USER DATA RF PACKET” and “SYNC RF packet”.This transmission scheme that allows asymmetric flow for uplink and downlink data transmission. When multiple TDD links are operated in co located deployment, there is a risk of receiver getting jammed during transmission by one of the transmitters.
[0004] FIG. 1A illustrates a co-site deployment scenario with "N" communication links operating simultaneously with "N" pairs of Master-Slave Radio communication equipment. The FIG. 1A shows a Master Entity which consists of "N" master radios which operate in close vicinity. Each of these Master Radios will form a link with corresponding Slave Radios using TDD channel sharing mechanism. The system includes N antennas connected to N Master Radios within the entity. "N" TDD Radio links are configured to work with "N" different frequencies. In order to establish reliable data links in this scenario, proper frequency separation and spatial separation of "N" antennas have to be established. In addition to these separations, co-site filters have to be used for each of "N" antennas to avoid interference in any of the radios during transmission by any other radio.
[0005] A conventional two co-located radio deployment scenario as shown in FIG. 1A requires both vertical and horizontal separation to obtain good RF isolation between antenna. Here, "N" Master Radios along with one or several data terminal equipment are connected to each other over a data hub such as an Ethernet Switch. The antennas of this deployment scenario further need to be separated based on the RF isolation required from adjacent antennas. Receiver sensitivity degradation is one of the major consequences of poor RF emission isolation of adjacent antennas. If the RF isolation between antennas is less, the wanted signal must have a higher power in order to be successfully received. This phenomenon is called Desensitization.The isolation between antennas with respect to distance between them can be calculated using Friis transmission formula:

Where,
Pr=Power received by Receive antenna
Pt=Power transmitted by transmitter
r = distance between 2 Antennas
Gt=Transmit Antenna gain
Gr=Receive antenna gain
?=wavelength of radio wave
[0006] FIG. 1B illustrates sequence of transmission and reception of two co located Master Radios of two Half duplex radio links that consist of 2 co located Radios. The shaded regions "I1" and "I2" indicated in the figure represent the interference caused at the receiver of Master Radio-1 by Master Radio-2 and receiver of Master Radio-2 by Master Radio-1. Receiver performance degradation in terms of sensitivity, BER etc. can be observed in respective radios during the occurrence of I1 and I2. FIG. 1C illustrates sequence of transmission and reception of co located Master Radios of multiple Point to Point links that consist of "N" co located Radios. Non aligned transmit time slots of various master radios lead to interference. FIG. 1D illustrates desensitization of the receivers due to poor RF isolation between them. As illustrated, if the RF isolation between antennas is less, the wanted signal must have a higher power in order to be successfully received. This phenomenon is called desensitization. This problem arises because the signal from the nearby transmitter is much stronger than that of the wanted signal which is received from radio transmitter located at far end. The nearby transmitter's power is radiated from its antenna which is much closer to the receiver antenna. If the interfering transmitter antenna is placed too close to the receiver, or if the transmitted power is too high, desensitization is possible even if the antennas operate on different frequencies. FIG. 1E illustrates frequency v/s time representation of 'n' co located Master Radios of multiple Half duplex Radio links.As illustrated, RF interference caused by neighboring radio transmission increases by multiple folds depending on the number of co located radios under deployment.
[0007] There is, therefore, a system for reducing or mitigating co-site interference between the radios that are positioned in close proximity with each other.

OBJECTS OF THE PRESENT DISCLOSURE
[0008] Some of the objects of the present disclosure, which at least one embodiment herein satisfies are as listed herein below.
[0009] It is an object of the present disclosure to provides a system for mitigating common site interference between the radios.
[0010] It is an object of the present disclosure to provides a system for mitigating common site interference between the radios which is cost effective.
[0011] It is an object of the present disclosure to provides a system for mitigating common site interference between the radios without GPS.
[0012] It is an object of the present disclosure to provides a system for mitigating common site interference that reduces the interference effects like receiver desensitization, inter-modulations etc.
[0013] It is an object of the present disclosure to provides a system for mitigating common site interference that omits requirement of maintaining large antenna spacing to achieve antenna isolation.
[0014] It is an object of the present disclosure to provides a system for mitigating common site interference that maintains optimal BER of Radio links in co-located deployment scenario.
[0015] It is an object of the present disclosure to provides a system for mitigating common site interference that maintains optimal antenna spacing in co-located antenna deployment scenario.
[0016] It is an object of the present disclosure to provides a system for mitigating common site interference that maintains optimal frequency separation between adjacent Half-duplex Radio links in co-located deployment scenario.
[0017] It is an object of the present disclosure to provides a system for mitigating common site interference that minimizes re-transmissions in co-located Radio systems which can occur due to cosite interference.

SUMMARY
[0018] The present disclosure relates to the field of co-location of the half duplex radios. More particularly the present disclosure relates to a system for mitigating co-site/common-site interference between the radios when positioned in close proximity to each other.
[0019] An aspect of the present disclosure pertains to a system for mitigating common-site interference between co-located radios. The system includes a plurality of first radios located at a first site, and the plurality of the first radios are communicatively coupled to an ethernet hub. One of the plurality of first radios is configured to generate and transmit timing reference ethernet packets to rest of the plurality of the first radios through the ethernet hub.The one of the plurality of the first radios that is configured to generate and transmit timing reference ethernet packet may be timing master. A plurality of second radios communicatively coupled to the plurality of first radios. The rest of the plurality of first radios are configured to transmit data to the plurality of second radios with respect to respective internal reference clocks post alignment with timing master, for mitigating the common site interference.
[0020] In an aspect, the plurality of the first radios may be communicatively coupled with the ethernet hub using an ethernet bus.
[0021] In an aspect, the plurality of the first radios may be communicatively coupled with the ethernet bus through their respective control ethernet interface.
[0022] In an aspect, the plurality of first radios may be master radios.
[0023] In an aspect, the plurality of second radios may be slave radios. The plurality of master and slave radio pairs may be communicatively coupled through RF using Antenna.
[0024] In an aspect, all the radios including plurality of first and second radios may be configured to generate an internal reference clock. The duration of internal reference clock may be equal to one time slot. The plurality of slave radios may align their clocks to respective radio in plurality of master radios.
[0025] In an aspect, the timing master radio may be configured to periodically broadcast a timing reference ethernet packet with respect to its internal reference clock. The periodicity of timing reference ethernet packet may be an integral multiple of time slot. The periodicity of the timing reference ethernet packet may depend up on clock drift of internal reference clock.
[0026] In an aspect, the plurality of master radios may be configured to transmit RF packet invalid rising edge of respective internal reference clock.
[0027] In an aspect, the timing master may be configured to broadcast the timing reference ethernet packet in the falling edge of its internal reference clock
[0028] In an aspect, the plurality of slave radios may be configured to align their internal reference clocks after the reception of a SYNC RF packet from their respective communicatively coupled master radios.
[0029] In an aspect, the plurality of master radios may be configured to send the SYNC RF packets to communicatively coupled slave radios at predefined intervals for maintaining TDD synchronization between master and slave pair.
[0030] In an aspect, the plurality of first radios may be communicatively coupled with a data hub, through a data interface.
[0031] In an aspect, the internal reference clock of the plurality of second radios may be a negated version of their respective communicatively coupled first radios.
[0032] In an aspect a valid internal reference clock transition is an internal reference clock transition at which internal reference clock alignment or RF packet transmission occurs and it might be configured either as raising or falling edge.
[0033] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF DRAWINGS
[0034] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure. The diagrams are for illustration only, which thus is not a limitation of the present disclosure.
[0035] In the figures, similar components and/or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label with a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.
[0036] FIG. 1A illustrates conventional co-site deployment scenario with "N" communication links operating simultaneously with "N" pairs of Master-Slave Radio communication equipment.
[0037] FIG. 1B illustratessequence of transmission and reception of two co-located Master Radios in the conventional scenario.
[0038] FIG. 1C illustratessequence of transmission and reception of two co-located Master Radios in the conventional scenerio, in accordance with an embodiment of the present disclosure.
[0039] FIG. 1D illustrates desensitization of the receivers due to poor RF isolation between them.
[0040] FIG. 1E illustrates frequency v/s time representation of 'n' co located Master Radios of multiple Half duplex Radio links.
[0041] FIG. 2 illustrates an exemplary representation of a system for mitigating co-site interference between co-located radios, in accordance with an embodiment of the present disclosure.
[0042] FIG. 3 illustrates timing of various events occurring while synchronizing all master radios in alignment with internal reference clock of the timing master, in accordance with an embodiment of the present disclosure.
[0043] FIG. 4 illustrates operation of timing master radio, in accordance with an embodiment of the present disclosure.
[0044] FIG. 5 illustrates operation of master radios except timing master, in accordance with an embodiment of the present disclosure.
[0045] FIG. 6 illustrates an application of proposed method in a deployment scenario with "N" co-located Radios to mitigate co-site interference, in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION
[0046] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0047] In the following description, numerous specific details are set forth in order to provide a thorough understanding of embodiments of the present invention. It will be apparent to one skilled in the art that embodiments of the present invention may be practiced without some of these specific details.
[0048] The present disclosure relates to the field of co-location of the half duplex radios. More particularly the present disclosure relates to a system for mitigating co-site/common-site interference between the radios when positioned in close proximity to each other.
[0049] FIG. 2 illustrates an exemplary representation of a system for mitigating co-site interference between co-located radios, in accordance with an embodiment of the present disclosure.
[0050] As illustrated, proposed system for mitigating common-site interference between co-located radios can include a plurality of first radios (102-1, 102-2…102-n) located at a first site, and the plurality of the first radios can be communicatively coupled to an ethernet hub 106. The plurality of first radios can also referred as master radios (102-1. 102….102-n), herein. The plurality of the first radios can be communicatively coupled with the ethernet hub using their respective control ethernet interface. One of the plurality of first radios 102-1 can be configured to generate and transmit timing reference ethernet packets to rest of the plurality of the first radios (102-2….102-n) through the ethernet hub. One of the plurality of first radios can also be referred as timing master 102-1 herein.
[0051] In an embodiment, a plurality of second radios (104-1, 104-2….104-n) can be distributed at multiple sites, and can be communicatively coupled to the plurality of first radios (102-1. 102-2….102-n). The plurality of second radios can also be referred as slave radios, herein. The rest of the plurality of first radios can be configured to transmit data to the plurality of second radios after aligning with the timing master, for mitigating the common site interference. The rest of the plurality of the second radios can represent each of the first radios (102-2…102-n) except the timing master 102-1.
[0052] In an embodiment, the plurality of the first radios (102-1, 102-2…102-n) can be communicatively coupled with the ethernet hub 106 using an ethernet bus. The timing master (102-1) can be configured to generate an internal reference clock, and can transmit the timing reference ethernet packets on a falling edge of every third clock cycle of the internal clock. The clock cycle for timing reference ethernet packets at its negative edge can be varied based on internal clock stability of the radios. The system can be configured to broadcast the transmission control packets with a predefined format at intervals equivalent to an integral multiple of a time slot. The timing reference ethernet packets can include an information related to timing of transmission and reception of the plurality of first radios (102-1, 102-2…102-n). The rest of the plurality of the first radios (102-2…102-n) can be configured to be aligned to the internal reference clock of the timing master, and transmit the data to the plurality of second radios on next rising edge, of respective internal reference clock. The plurality of first radios (102-1, 102-2..102-n) can be communicatively coupled with a data hub 110, through a data interface 108.
[0053] In an embodiment, all the radios including plurality of master and slave radios can be configured to generate an internal reference clock. The duration of internal reference clock can be equal to one time slot. The plurality of slave radios can align their clocks to respective radio in plurality of master radios. The timing master radio can be configured to periodically broadcast a timing reference ethernet packet with respect to its internal reference clock. The periodicity of timing reference ethernet packet can be an integral multiple of time slot. The periodicity of the timing reference ethernet packet can depend up on clock drift of internal reference clock. The plurality of slave radios can be configured to align their internal reference clocks after the reception of a SYNC RF packet from their respective communicatively coupled master radios. The plurality of master radios may be configured to send the SYNC RF packets to communicatively coupled slave radios at predefined intervals for maintaining TDD synchronization between master and slave pair.
[0054] FIG. 3 illustrates timing of various events occurring while synchronizing all master radios in alignment with internal reference clock of the timing master, in accordance with an embodiment of the present disclosure.
[0055] As illustrated, the timing master 102-1 generates, using internal processing elements, an internal clock signal can have equal high and low durations and a period equivalent to the duration of transmission in a single time slot. The internal processing element can include but not limited to microcontroller or FPGA to generate this reference clock. The Timing Master can transmit a timing reference ethernet packet over its control ethernet interface 112-1, at negative edge of clock cycle. It is ensured that only the timing master radio 102-1 transmits over the ethernet hub 106. All the remaining master radios (102-2…102-n) can be connected using their respective control ethernet interfaces (112-2…112-n). The rest of the master radios (102-2…102-n) are configured to work in receive mode over their control ethernet interfaces. Timing Master Radio 102-1 dictates the timing of transmission and reception of all co-located radios in the Master entity. Each of the co-located radio considers this packet reception as a trigger to align its internal reference clock. 1?Internal reference clock of Master-1 Radio which dictates the timing of all Radios of the Master entity
[0056] In an embodiment, in FIG. 3, ‘2’ can represent an internal reference clock of master-1 radio before synchronization. ‘3’ can represent timing reference ethernet packet broadcasted by master-1 radio over Ethernet hub. ‘4’ can represent timing reference ethernet packet received by master-2 radio. ‘5’ can represent master-2 radio internal reference clock reset in order to align with master-1 clock. ‘6’ can represent master-2 radio internal reference clock after synchronization. ‘7’ can represent the internal reference clock of master-n radio before synchronization. ‘8’ can represent timing reference ethernet packet received by master-n radio. ‘9’ can represent master-n radio internal transmission clock reset in order to align with Master-1 clock. ‘10’ can represent master-n Radio transmission clock after synchronization.
[0057] FIG. 4 illustrates operation of timing master radio, in accordance with an embodiment of the present disclosure.
[0058] As illustrated, the timing master radio 102-1 initially generates its internal reference clock using processing element such as a microcontroller or FPGA. The reference clock signal forms the reference for transmission time slot of the radio as well as reference for transmitting timing reference ethernet packet to be sent during one falling edge of a pre-defined integral multiple of time slot. The timing master radio 102-1 transmit transmitting timing reference ethernet packet through its control ethernet interface 112-1 which is distributed to other master radios (except timing master) using an ethernet hub. At rising edge and at a pre-defined slot for SYNC RF packet, the SYNC RF packet is transmitted through the antenna. Otherwise, user data RF packet (also referred as user data, herein) is transmitted if user data is available.
[0059] FIG. 5 illustrates operation of master radios except timing master, in accordance with an embodiment of the present disclosure.
[0060] As illustrated, FIG. 5 illustrates a method used by the master radios (except the timing master) to align internal reference clock to that of the timing master. Initially, the rest of the master radios operate with respect to their respective internal reference clock for transmission of RF packets. After receiving the Timing reference ethernet packets broadcasted by timing master, the rest of the master radios reset their internal reference clock for aligning with the internal reference clock of the timing master. This alignment also considers the fixed delays associated with Ethernet communication. Further, at rising edge and at a pre-defined slot for SYNC RF packet, SYNC RF packet will be transmitted. Otherwise, user data RF packet is transmitted, when available, through respective antennas. The method ensures that all master radios go to transmit mode in the same time slot by accurately adjusting the internal reference clocks of all master radios. The method of simultaneous transmission and reception by co-located radios enables eliminating the negative effects of co-site interference on all the communication links in co-located Radio deployment scenario.
[0061] FIG. 6 illustrates an application of proposed method in a deployment scenario with "N" co-located Radios to mitigate co-site interference, in accordance with an embodiment of the present disclosure.
[0062] As illustrated, timing of transmission time slots is aligned precisely by the timing master radio by broadcasting IP packets at a pre-determined interval. The method reduces the cost involved in using co-site filters as well as reduces the interference effects like receiver desensitization, inter-modulations etc. This method also reduces the requirement of maintaining large antenna spacing to achieve RF isolation.
[0063] Moreover, in interpreting the specification, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refer to at least one of something selected from the group consisting of A, B, C ….and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc.
[0064] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

ADVANTAGES OF THE INVENTION
[0065] The proposed invention provides a system for mitigating common site interference between the radios.
[0066] The proposed invention provides a system for mitigating common site interference between the radios which is cost effective.
[0067] The proposed invention provides a system for mitigating common site interference between the radios without GPS.
[0068] The proposed invention provides a system for mitigating common site interference that reduces the interference effects like receiver desensitization, inter-modulations etc.
[0069] The proposed invention provides a system for mitigating common site interference that omits requirement of maintaining large antenna spacing to achieve antenna isolation.
[0070] The proposed invention provides a system for mitigating common site interference that maintains optimal BER of Radio links in co-located deployment scenario.
[0071] The proposed invention provides a system for mitigating common site interference that maintains optimal antenna spacing in co-located antenna deployment scenario.
[0072] The proposed invention provides a system for mitigating common site interference that maintains optimal frequency separation between adjacent Half-duplex Radio links in co-located deployment scenario.
[0073] The proposed invention provides a system for mitigating common site interference that minimizes re-transmissions in co-located Radio systems which can occur dueto cosite interference.