Structure for OTA ENB-ENB communication

According to one general aspect, an apparatus may include a processor. In various embodiments, the processor may be configured to select either an uplink sub-frame or a special sub-frame to employ for base station-to-base station (B2B) communication in some embodiments, the processor may be configured to cause at least one user equipment (UE), associated with the apparatus, to either refrain from transmitting or substantially receiving during the selected sub-frame In various embodiments, the processor may be configured to transmit data, from the apparatus to a receiving BS, during at least a portion of the selected sub-frame.

TECHNICAL FIELD

This description relates to communications, and more specifically to the over the air (OTA) communication between two or more evolved Node Bs (eNBs) or base stations (BSs).

BACKGROUND

Long Term Evolution (LTE) describes the latest standardization work by 3rd Generation Partnership Project (3GPP) in the area of mobile network technology in preparation for further increasing user demands and tougher competition from new radio access technologies, LTE is generally being enhanced with a new radio access technique called LTE-Advanced. Via this technology LTE is expected to improve end-user throughput, increase sector capacity, reduce user plane latency, and consequently offer superior user experience with full mobility.

The Evolved UMTS Terrestrial Radio Access (E-UTRA) standard typically includes the air interface of 3GPP's LTE for mobile networks. An E-UTRA network or, as it is occasionally referred to, a LTE network includes a network that is substantially in compliance with the LTE standards, their derivatives, or predecessors (hereafter, “the LTE standard” or “Release 8 standard”). 3rd Generation Partnership Project,Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access(E-UTRA);Physical Channels aid Modulation(Release8), 3GPP TS 36.211 V8.4.0 (2008-09), September 2008.

SUMMARY

According to one general aspect, an apparatus may include a processor. In various embodiments, the processor may be configured to select either an uplink sub-frame or a special sub-frame to employ for base station-to-base station (B2B) communication. In some embodiments, the processor may be configured to cause at least one user equipment (UE), associated with the apparatus, to either refrain from transmitting or substantially receiving during the selected sub-frame. In various embodiments, the processor may be configured to transmit data, from the apparatus to a receiving BS, during at least a portion of the selected sub-frame.

According to another general aspect, a method of using a transmitting base station (BS) may include selecting either an uplink sub-frame or a special sub-frame to employ for base station-to-base station (B2B) communication, in some embodiments, the method may also include causing at least one user equipment (UE), associated with the transmitting BS, to either refrain from transmitting or substantially receiving during the selected sub-frame. In one embodiment, the method may include transmitting data, from the transmitting BS to a receiving BS, during at least a portion of the selected sub-frame.

According to another general aspect, an apparatus may include a means for selecting either an uplink sub-frame or a special sub-frame to employ for base station-to-base station (B2B) communication. In various embodiments, the apparatus may include a means for causing at least one user equipment (UE), associated with the transmitting BS, to either be communicatively muted or substantially communicatively deafened during the selected sub-frame. In some embodiments, the apparatus may include a means for transmitting data, from the transmitting BS to a receiving BS, during at least a portion of the selected sub-frame.

According to another general aspect, a machine readable medium may include instructions capable of being executed by at least one machine. In various embodiments, the instructions, when executed, cause the machine to select either an uplink sub-frame or a special sub-frame to employ for base station-to-base station communication. In some embodiments, the instructions may cause at least one user equipment, associated with the transmitting base station, to either refrain from transmitting or substantially receiving within the selected sub-frame. In various embodiments, the instructions may transmit data, from a transmitting base station to a receiving base station, during at least a portion of the selected sub-frame.

A system and/or method for communicating information, substantially as shown in and/or described in connection with at least one of the figures, as set forth more completely in the claims.

DETAILED DESCRIPTION

Referring to the Figures in which like numerals indicate like elements.FIG. 1is a block diagram of a wireless network102including an evolved Node Bs (eNBs) or base station (BS)104and user equipment (UE) or mobile stations (MSs)106,108,110, according to an example embodiment. Each of the MSs106,108,110may be associated with BS104, and may transmit data in an uplink (UL) direction to BS104, and may receive data in a downlink (DL) direction from BS104, for example. Although only one BS104and three mobile stations (MSs106,108and110) are shown, any number of base stations and mobile stations may be provided in network102. Also, although not shown, mobile stations106,108and110may be coupled to base station104via relay stations or relay nodes, for example. The base station104may be connected via wired or wireless links to another network (not shown), such as a Local Area Network (LAN), a Wide Area Network (WAN), the Internet, etc. In various embodiments, the base station104may be coupled or connected with the other network120via an access network controller (ASN) or gateway (GW)112that may control, monitor, or limit access to the other network.

FIG. 2is a block diagram of an example embodiment of a system200in accordance with the disclosed subject matter. As described above, in various embodiments, the UEs or MSs may be in communication with their respective eNBs or BSs. In addition, the BSs may be communication with each other. In one embodiment, the system200may include a BS220in direct communication with a MS210and the BS222. The BS222may be in direct communication with the MSs206and206, and the BS220. In various embodiments, the BS220may have a certain wireless range212. Likewise the BS222may have a wireless range214.

In various embodiments, it may be desirable for the BS220and the BS222to communicate with each other, BS-to-BS (B2B) communication, in various embodiments, this may be accomplished via out-of-band communication (e.g., via a gateway, etc.). In another embodiment, this communication may include an over the air (OTA) transmission between the two BSs220and222(illustrated by link216). In such an embodiment, the B2B communication may include use of the same antennas, physical communication resources (e.g., sub-frames, etc.) used to communicate with the respective MSs (e.g. MSs206,208, and210). In such an embodiment, time division duplexing (TDD) or time division multiplexing (TDM) DM) may be employed.

In various embodiments, an eNB or BS (e.g., BS220or BS222) may not be capable of transmitting and receiving at the same time via the same radio resources. Therefore, in one embodiment, it may be required that the eNB or BS mutes or stop its transmission during OTA communication (OTAC) reception.

In various embodiments involving LTE, downlink transmission is often continuous in the downlink part of the radio frame. For example, some signals (e.g., reference signals, synchronization signals, Physical Downlink Control Channel and other control channels, etc.) may be substantially continuously transmitted. In various embodiments involving the Release 8 standard, UEs or MSs may expect that, for example, reference signals are always transmitted in downlink sub-frames, and that the UEs or MSs may perform channel estimation and power measurements using those reference signals. Thus if the eNB or BS for some reason is not transmitting the reference signals, a UE or MS may make incorrect channel estimation and mobility measurements.

In various embodiments, when OTA B2B communication is desired, the transmitting BS (illustrated as BS220) may select a sub-frame to use to communication with the receiving BS (illustrated as BS222) that will not result in a UE or MS (e.g., MS210, etc) making incorrect channel estimation and mobility measurements, for example, in one embodiment, this may include selecting a non-DL sub-frame to employ or use to OTA B2B communication. In the illustrated embodiment, the BS220may be denoted as a transmitting BS, and the BS222as the receiving BS; it is understood that communication is not necessarily unidirectional and that these labels are merely for the sake of illustration. It is understood that bi-directional BS-to-BS (B2B) communication is included in the disclosed subject matter.

FIG. 3is a block diagram of an example embodiment of a system or apparatus301in accordance with the disclosed subject matter. The apparatus or wireless station301(e.g., base station104, mobile station106, relay station, etc) may include, for example, an RF (radio frequency) or wireless transceiver302, including a transmitter to transmit signals and a receiver to receive signals, a processor or baseband processor304to execute instructions or software and control transmission and receptions of signals, and a memory306to store data and/or instructions.

Processor304may also make decisions or determinations, generate frames or messages for transmission, decode received frames or messages for further processing, and other tasks or functions described herein. Processor304, which may be a baseband processor, for example, may generate messages, packets, frames or other signals for transmission via wireless transceiver302. Processor304may control transmission of signals or messages over a wireless network, and may receive signals or messages, etc., via a wireless network (e.g., after being down-converted by wireless transceiver302, for example). Processor304may be programmable and capable of executing software, firmware, or other instructions stored in memory or on other computer media to perform the various tasks and functions described above, such as one or more of the tasks or methods described above. Processor304may be (or may include), for example, hardware, programmable logic, a programmable processor that executes software or firmware, and/or any combination of these. Using other terminology, processor304and transceiver302together may be considered as a wireless transmitter/receiver system, for example.

In addition, a controller (or processor)308may execute software and instructions, and may provide overall control for the station301, and may provide control for other systems not shown inFIG. 3, such as controlling input/output devices (e.g., display, keypad), and/or may execute software for one or more applications that may be provided on wireless station301, such as, for example, an email program, audio/video applications, a word processor, a Voice over IP application, or other application or software.

In addition, a storage medium may be provided that includes stored instructions, which when executed by a controller or processor may result in the processor304, or other controller or processor, performing one or more of the functions or tasks described above.

FIG. 4is a block diagram of an example embodiment of a series of physical resource units (grouped as, for example, frames, super-frames, sub-frames, etc.) in accordance with the disclosed subject matter. In one embodiment, the eNB or base station and various UEs or mobile stations may communicate with each other using a series or plurality of physical resource units (PRUs) organized into frames402or super-frames400; although, it is understood that various embodiments using other communication standards may organize PRUs differently.

FIG. 4illustrates a plurality of frames. In various embodiments, the plurality of frames may be organized into a super-frame400. In one embodiment, this super-frame400may include frames402a,402b,402, and402n. Frame402may include a down-link (DL) portion, an uplink (UL) portion and a special (SP) portion.

In various embodiments, a DL sub-frame404may be reserved for communication from the base station to a mobile station. Conversely, an UL sub-frame408may be reserved for communication from the mobile station to the base station. Downlink (DL) may refer to a direction of transmission from base station to a mobile station, and uplink (UL) may refer to a direction of transmission from a mobile station to a base station.

In various embodiments, a special (SP or S) sub-frame406may be used to transmit pilot information and provide a gap period, in which the BS may transition from transmitter to receiver (e.g., DL to UL), in some embodiments, the SP sub-frame406may include at least three fields: Downlink Pilot Timeslot (DwPTS), Guard Period (GP), and Uplink Pilot Timeslot (UpPTS), as described below.

In one embodiment, a frame402may include at least one DL sub-frame (e.g., DL sub-frames404and404a, etc.), at least one SP or S sub-frame (e.g., SP sub-frames406and406a, etc.) and at least one UL sub-frame (e.g., UL sub-frames408,408a,408b,408c,408d, and408e, etc.). In various embodiments, a SP or S sub-frame406and406amay, respectively, delineate the transition between the DL and UL portions of the frame402.

In various embodiments, a DL sub-frame404or UL sub-frame408may include messages or signals generally intended for a specific receiver or group of receivers. Occasionally these sub-frames may be used to broadcast control information (e.g., resource allocation, channel condition feedback, etc.), or more typically user data.

FIG. 5is a block diagram of an example embodiment of a special (S) sub-frame500in accordance with the disclosed subject matter. In one embodiment, a transmitting BS (e.g., BS220ofFIG. 2) may use an S sub-frame to communicate with a receiving BS (e.g., BS222ofFIG. 2). In one embodiment, the S sub-frame may include a Downlink Pilot Timeslot (DwPTS)502, a Guard Period (GP) portion504, and Uplink Pilot Timeslot (UpPTS)506.

In various embodiments, the DwPTS502may include a Physical Downlink Control Channel (PDCCH) portion508, and a Physical Downlink Shared Channel (PDSCH) portion510. In some embodiments, the PDCCH508may include scheduling assignments and other control information. In various embodiments, the PDSCH510may include higher layer control information (e.g., system information, a synchronization signal, etc.) or user data.

In various embodiments, the GP504may include a period of time in which transmission and reception are muted or not scheduled to occur in various embodiments, such a time period may allow re-configuration of the antenna or transceiver of a device from receiver to a transmitter or vice versa. In various embodiments including loosely synchronized systems or asynchronous systems, the GP504may also account for transmission time between devices (e.g., eNB & UE, BS or MS, etc.).

In one example embodiment, a BS or eNB may select from a plurality of versions of the S sub-frame. In various embodiments, (e.g., the Release 8 standard) a special sub-frame configuration with a long or extended guard period (GP) may be signaled by the BS or eNB to the UEs or MSs. For example, such S sub-frame configurations may include configurations 0 or 5 as specified in Release 8 standard with a GP504of 10 or 9 symbols, respectively. See, 3rd Generation Partnership Project,Technical Specification Group Radio Access Network; Evolved Universal Radio Access(E-UTRA);Physical Channels and Modulation(Release8), Table 4.2-1; Configuration of special subframe (lengths of DwPTS/GP/UPpTS), 3GPP TS 36.211 V8.4.0 (2008-09), September 2008. In various embodiments, the symbols may include orthogonal frequency-division multiplexing (OFDM) symbols.

In various embodiments, however, only a GP504of one or two symbols may be required in local area scenarios. In such an embodiment, some of the extra long or extended GP504may be now utilized for OTA B2B communication. For example, in one embodiment, if an S sub-frame configuration with a GP of 10 symbols, one or two symbols may be used to an actual GP, leaving 8 or 9 symbols available for OTA B2B communication. Although, it is understood that the above is merely one illustrative example to which the disclosed subject matter is not limited.

In various embodiments, a BS or eNB may signal to the MSs or UEs that an S sub-frame including an extended GP portion504is scheduled to occur (e.g., S sub-frame500). In such an embodiment, the MSs or UEs may react as if the S sub-frame500is occurring. During the extended GP504, the MSs or UEs may stop or refrain from their typical channel measurement, etc. and react as if they consider the BS or eNB transmissions to be muted or substantially silent. Likewise, the MSs and UEs may be configured to refrain from transmitting during this extended GP504. However, in actuality, in one embodiment, the BS or eNB may employ the S sub-frame501.

In one embodiment, the S sub-frame501may include an extended DwPTS portion518. In various embodiments, the extended DwPTS portion518may include a PDCCH508, a PDSCH510, a first GP514, an OTA B2B communication portion516, and a second GP520. In various embodiments, only one GP portion may be included. In such an embodiment, the eNB may transmit or receive data from a second eNB during the OTA B2B communication portion516, without interfering with the MSs and UEs as those devices are ignoring the supposedly muted or silenced eNB (as they expect the eNB to be in the extended GP portion504).

In various embodiments, the transmitting eNB or BS (e.g., BS220), may use the last symbol or symbols of the extended DwPTS518or first OFDM symbols of the configured GP to transmit OTA B2B information (e.g., OTA B2B communication516). In various embodiments, the number of symbols (e.g., OFDM symbols) available or employed to the OTA B2B (portion516) may depend upon the signaled or indicated S sub-frame configurations and/or additional system information.

In various embodiments, the receiving eNB or BS (e.g., BS222ofFIG. 2) may include the typical non-extended DwPTS portion502(e.g., PDCCH508. PDSCH510, etc) and switch to receiving OTA B2B communication mode right, after transmitting last symbol of the typical non-extended DwPTS. In such an embodiment, the first GP514may be used to transition to receiving mode. The OTA B2B communication from the transmitting BS or eNB (e.g., BS220) may be received during the OTA B2B communication portion516.

In various embodiments, the transmitting eNB or BS may insert a GP514before starting the OTA B2B transmission516to account for synchronization errors and transceiver re-configuration time (e.g., of the receiving eNB or BS, etc.). In another embodiment, a second GP520may be inserted after the OTA B2B transmission516to account to, once again account for synchronization errors and transceiver re-configuration time (e.g., of the transmitting eNB or BS, etc.) and to provide a substantially quite period for UEs or MSs to transmit their respective UpPTS506which may be timed (due to, for example, propagation delay, etc.) to arrive at the eNB or BS during the illustrated UpPTS506period.

In various embodiments, the first symbol of the OTA B2B communication516may include an extended or longer cyclic prefix (CP) acting as a GP (e.g., GP514) or producing a substantially similar effect. In some embodiments, the cyclic prefix of a symbol (e.g., an OFDM symbol) may include a repeat of the end of the symbol at the beginning symbol. In various embodiments, an extended CP may include 16.67 μs or more; although, it is understood that the above is merely one illustrative example to which the disclosed subject matter is not limited. In some embodiments, the use of an extended CP as a GP, for example to allow for eNB or BS DL-UL switching, time, may be employed in a system in which the synchronization errors are small; although, it is understood that the above is merely one illustrative example to which the disclosed subject matter is not limited.

In another embodiment, one or more whole symbols may be used as the GP514or520, as described above. Although, it is understood that the above is merely one illustrative example to which the disclosed subject matter is not limited.

In various embodiments, the transmitting eNB or BS (e.g., BS220ofFIG. 2) may utilize the downlink transmission schemes (e.g., timing, encoding, etc.) for the OTA B2B communication516. However, in other embodiments, the uplink transmission schemes may be utilized. In some embodiments, employing the uplink transmission schemes may be easier to implement since the eNB or BS receiver may be reused. In such an embodiment, neither the DL nor the UL schemes may be used for the OTA B2B communication516. It is understood that the above are merely a few illustrative examples to which the disclosed subject matter is not limited.

FIG. 6is a block diagram of an example embodiment of a sub-frame601in accordance with the disclosed subject matter. In one embodiment, the S sub-frame601may include a DwPTS portion502, an extended GP504, and an UpPTS506. Sub-frame601illustrates that, in one embodiment, OTA B2B communication portion516may occur as part of the extended GP504, as opposed to an extended DwPTS518ofFIG. 5. In various embodiments, the resultant sub-frame may be substantially equivalent; however, the implementation and conceptual view of the sub-frame and the OTA B2B communication may differ. However, either conception, implementation or their substantial equivalents are within the scope of the disclosed subject matter.

FIG. 10is a block diagram of an example embodiment of a sub-frame1001in accordance with the disclosed subject matter. In one embodiment, the transmitting eNB or BS may indicate that an extended DwPTS period1002and a non-extended GP1004will occur, resulting in the sub-frame1000. For example, such S sub-frame configurations may include configurations 4 or 8 as specified in Release 8 standard, as described above, having a GP512of 1 symbol. In such an embodiment, it may appear to the UEs or MSs as if the PDSCH1010is extended. However, in various embodiments, the eNB or BS may take or employ some symbols from this extended DwPTS1002for OTA B2B communication516and a GP514, resulting in the actual sub-frame1001. In various embodiments, the GP514of the extended DwPTS1018may be absent if an extended cyclic prefix is used for the first OTA B2B symbol, as described above.

FIG. 8is a block diagram of an example embodiment of a frame802in accordance with the disclosed subject matter. In another embodiment, the OTA B2B communication may occur during a presumptive UL sub-frame.

In various embodiments, the eNB or BS may indicate when DL, UL or S (SP) sub-frames may occur. In some embodiments, the eNB or BS may select a frame configuration from a list of possible frame configurations dictated by a standard (e.g., the Release 8 standard, etc.). One such configuration is illustrated in frame402(reproduced inFIG. 8fromFIG. 4).

Furthermore, in various embodiments, the eNB or BS allocates time and frequency segments (e.g., resource units, resource blocks, etc.) for communication with its respective UEs or MSs, as described above. Therefore, an eNB or BS may dictate when and from where a transmission will occur during any given UL sub-frame.

In various embodiments, the eNB or BS may select one or more UL sub-frames for OTA B2B communication.FIG. 8illustrates once such configuration in which UL sub-frame408bis selected as a B2B communication sub-frame810. In various embodiments, this may occur by the eNB or BS selecting an uplink (UL) sub-frame to employ for B2B communication, and allocating the selected UL sub-frame to none of the UEs. In various embodiments, this may be referred to as the eNB or BS “stealing” a UL sub-frame for B2B communication. In various embodiments, the replacement of a UL sub-frame with a B2B sub-frame need not occur every frame, merely when needed or convenient for the eNB or BS.

As described above inFIGS. 5 and 6, in such an embodiment, the UEs and MSs need not be aware that a B2B communication is occurring. Furthermore, as withFIGS. 5 and 6, such an embodiment may be employed without a need to alter the set of possible frame configurations dictated by the networking standard used.

In such an embodiment, from the UEs or MSs point of view the B2B sub-frame810may appear to be a standard but unallocated UL sub-frame (e.g. UL sub-frame408b). During such an unallocated UL sub-frame, the UEs or MSs may be, in one embodiment, muted or substantially silent as they refrain from transmission due to lack of allocation.

In such an embodiment, during the unallocated UL sub-frame (e.g., B2B sub-frame810), the transmitting eNB or BS may switch from a receiving configuration to a transmitting configuration. The transmitting BS may then, in one embodiment, transmit OTA B2B information to a receiving BS (e.g., BS222ofFIG. 2). In various embodiments, the entire or merely of a portion of the sub-frame may be used, depending on the amount of information to be transmitted. In various embodiments, the transmitting BS may then switch back from the transmitting configuration to a receiving configuration, depending upon whether or not the immediately subsequent sub-frame is a DL sub-frame or a UL sub-frame.

In some embodiments, a receiving eNB or BS may monitor or be aware of the transmitting BS's UL sub-frame allocations. In such an embodiment, when the transmitting eNB or BS does not allocate a UL sub-frame to any UEs or MSs, the receiving BS or eNB may expect a B2B communication to occur during that sub-frame. In some embodiments, the receiving BS may be incorrect and the sub-frame may merely be unallocated and not “stolen” for B2B purposes. In another embodiment, the transmitting eNB or BS may indicate (e.g., directly, indirectly via a gateway, indirectly via inference and/or assumption, etc.) to the receiving base station BS, which UL sub-frame (or more generally non-DL sub-frame; e.g., in the case of embodiments illustrated byFIGS. 5 and 6) has been selected for B2B communication. Although, it is understood that the above are merely a few illustrative examples to which the disclosed subject matter is not limited.

In various embodiments, an eNB or BS may select a particular UL sub-frame in order to minimize loss of system or device efficiency, in one embodiment, the eNB or BS may select the uplink (UL) sub-frame directly before a DL sub-frame to employ for B2B communication. In such an embodiment, this may mean that the eNB or BS need not switch its transceiver from a receiving configuration to a transmitting configuration more than it would had a non-B2B frame occurred. In such an embodiment, the eNB or BS would merely switch modes one sub-frame earlier than in the equivalent non-B2B frame (e.g., frame802versus frame402).

In another embodiment, the B2B transmission period may be extended beyond one UL sub-frame (e.g., 2 UL sub-frames, etc.). In such an embodiment, a frame configuration (seeFIG. 7) may be chosen that facilitates the selection of multiple UL sub-frames for use in B2B communication.

FIG. 7is a table700of example embodiments of a system in accordance with the disclosed subject matter. Table700illustrates a plurality of frame configurations that may be predefined by a standard (e.g., the Release 8 standard, etc.) or generally used in various embodiments, in various embodiments, the highlighted UL sub-frames720may be employed or “stolen” for B2B communication; although, it is understood that the above are merely a few illustrative examples to which the disclosed subject matter is not limited. For example, if configuration702is employed sub-frame4(a UL sub-frame) may be unallocated to any UEs or MSs and used instead for B2B communication.

In the illustrated embodiment, the last UL sub-frame directly before a DL sub-frame is employed for B2B communication it is understood that the illustrated is merely one example to which the disclosed subject matter is not limited and that sub-frames not directly before a DL sub-frame may be employed.

FIG. 9is a flow chart of an example embodiment of a technique900in accordance with the disclosed subject matter. In various embodiments, the technique900may be performed by the system ofFIG. 1or2, the apparatus ofFIG. 3, as described above. In some embodiments, the technique900may be used with a sub-frame as illustrated byFIGS. 5and/or6, as described above. In some embodiments, the technique900may be used with a frame as illustrated byFIGS. 7and/or8, as described above.

Block902illustrates that, in one embodiment, a non-downlink (DL) sub-frame may be selected by an eNB or BS to be employed for base station-to-base station (B2B) communication, as described above. In one embodiment, selecting ma include indicating to at least one UE that a sub-frame including an extended guard period (GP) will occur, as described above in such an embodiment, the selected sub-frame may include a downlink pilot time slot (DwPTS) portion, and a GP portion, and the extended GP portion may include at least one GP, and a B2B communication portion, as described above, in one embodiment, the selected sub-frame may include an extended downlink pilot time slot (DwPTS) portion, and a GP portion, and the extended DwPTS portion may include a non-extended DwPTS portion, at least one GP, and a B2B communication portion, as described above. In various embodiments, the action(s) illustrated by this block may be performed by various elements, such as the BS104ofFIG. 1, the BS220ofFIG. 2, the apparatus301, and/or the processor304ofFIG. 3, as described above.

In another embodiment, selecting may include selecting an uplink (UL) sub-frame to employ for B2B communication, and allocating the selected UL sub-frame to none of the UEs or MSs, as described above. In some embodiments, allocating may include causing the receiving BS to expect a B2B communication, as described above. In one embodiment, selecting may include selecting an uplink (UL) sub-frame directly before a sub-frame to employ for B2B communication, as described above. In various embodiments, the action(s) illustrated by this block may be performed by various elements, such as the BS104ofFIG. 1, the BS220ofFIG. 2, the apparatus301, and/or the processor304ofFIG. 3, as described above.

Block904illustrates that, in one embodiment, the eNB or BS may cause at least one user equipment (UE) or MS, associated with the eNB or BS, to either refrain from transmitting or substantially receiving during the selected in-band non-downlink sub-frame, as described above. In one embodiment, causing or refraining from substantially receiving (e.g., performing channel measurements, etc.) may include indicating to the UEs or MSs that a guard period (GP) will occur when in actually a B2B communication will occur, as described above, in another embodiment, causing or refraining from transmitting may include not allocating a selected UL sub-frame to any of the UEs or MSs, as described above. In various embodiments, the action(s) illustrated by this block may be performed by various elements, such as the BS104ofFIG. 1, the BS220ofFIG. 2, the apparatus301, and/or the processor304and/or transceiver302ofFIG. 3, as described above.

Block906illustrates that, in one embodiment, the eNB or BS may indicate, to the receiving base station (BS), which non-downlink sub-frame has been selected or that a B2B communication will occur, as described above. In one embodiment, indicating may include causing the receiving BS to expect a B2B communication due to no UL allocations to a UE or MS occurring during a UL sub-frame, as described above. In various embodiments, the slots or sub-frames for B2B communication may be configured beforehand via wired interface, in one embodiment, In another embodiment, the slots or sub-frames may be configured during base station start-up by listening to the broadcast information of other base stations before starting normal operation. In such an embodiment, this broadcast information may include indications about which slots or sub-frames are used for B2B communication. In other embodiments, indicating may include a message (e.g., direct, indirect via a third device, indirect via inference, etc.), as described above. In various embodiments, the action(s) illustrated by this block may be performed by various elements, such as the BS104ofFIG. 1, the BS220ofFIG. 2, the apparatus301, and/or the processor304and/or transceiver302ofFIG. 3, as described above.

Block908illustrates that, in one embodiment, the eNB or BS may transmit data, from the transmitting BS to a receiving BS, during at least a portion of the selected in-band non-downlink sub-frame, as described above. In one embodiment, transmitting may include during at least a portion of the extended GP, transmitting data to the receiving BS, as described above. In another embodiment, transmitting may include during at least a portion of the selected UL sub-frame, transmitting data to the receiving BS, as described above. In various embodiments, the action(s) illustrated by this block may be performed by various elements, such as the BS104ofFIG. 1, the BS220of2, the apparatus301, and/or the processor304and/or transceiver302ofFIG. 3, as described above.

In various embodiments, the transmitting eNB or BS and the receiving eNB or BS may be configured to operate substantially asynchronously. In another embodiment, the transmitting eNB or BS and the receiving eNB or BS may be configured to operate loosely synchronously, as described above. In yet another embodiment, the eNBs or BSs may be strictly synchronized.