Method and apparatus for conveying antenna configuration information

Embodiments of the present invention relate generally to communications between a network entity, such as a base station, and a recipient, such as a mobile terminal, and, more particularly, relate to a method and apparatus for conveying antenna configuration information.

In conventional wireless communications systems, mobile devices or other user equipment transmit information to a network, and receive information from a network, such as via a base station. In some networks, the base stations or other network entities which transmit information to the user equipment may include different antenna configurations, such as different numbers of antennas, e.g., one antenna, two antennas or four antennas, and/or may transmit the information in accordance with different transmission diversity schemes. In this regard, a base station with a single antenna may transmit information without any transmission diversity scheme, while base stations with two or four antennas may transmit information in accordance with a transmission diversity scheme or a specific transmission diversity scheme out of a set of different available transmission diversity schemes. As used herein, the information regarding the antenna configuration, e.g., the number of antennas, and/or the transmission diversity scheme shall be commonly referenced (both individually and collectively) as antenna configuration information. In order to effectively receive information from a base station, for example, the user equipment must have know or recognize the antenna configuration and/or the transmission diversity scheme utilized by the base station. A mobile device is able to properly demodulate a received signal only after correctly determining the antenna configuration, i.e., the number of transmit antennas and/or the transmission diversity scheme of a base station. Since the antenna configuration information is needed in order to properly demodulate the received signal, the antenna configuration information must be determined by the user equipment with very high reliability.

For example, in an Evolved Universal Mobile Telecommunication System (UMTS) Terrestrial Radio Access Network (E-UTRAN), the user equipment can gather antenna configuration information regarding the base station, termed an eNodeB in E-UTRAN, using data contained within orthogonal frequency division multiplexing (OFDM) symbols of a message. By way of example, the technical specifications of the Third Generation Partnership Project (3GPP) and, in particular, 3GPP TS 36.211, REL 8 and 3GPP TS 36.212, REL 8 allows for an approach for providing antenna configuration information. In this regard, the user equipment can extract antenna configuration information from provided reference signals or by attempts to decode data within a physical broadcast channel (PBCH).

FIGS. 1a-1f depict sub-frames within a conventional cyclical prefix for various antenna configurations and transmission diversity schemes in an E-UTRAN system. The sub-frames of FIGS. 1a-1f include six physical resource blocks (PRBs), i.e. 1080 kHz (72 sub-carriers), each of which comprises a sub-frame #0. Each sub-frame can consist of a plurality of resource elements which fill two slots, namely, a slot #0 and a slot #1. Each slot can, in turn, be comprised of a series of orthogonal frequency division multiplexing (OFDM) symbols which represent respective channels of information. In this regard, the sub-frames of FIGS. 1a-1f can include a physical downlink (or download) control channel (PDCCH), a physical downlink shared channel (PDSCH), a primary synchronization channel (P-SCH), a secondary synchronization channel (S-SCH), a physical broadcast channel (PBCH), and unused sub-carriers.

The E-UTRAN sub-frame #0 also includes a plurality of reference signals which fill predetermined resource elements which depend upon the antenna configuration. For example, in the sub-frames of FIGS. 1a-1f, the reference signals are designated R0, R1, R2, and R3 and are transmitted from a first, second, third and fourth antenna of the eNodeB respectively. In an E-UTRAN system, an eNodeB may include one, two or four antennas, each of which employs a different transmission diversity scheme. As shown, the sub-frame #0 may place the reference signals within different predetermined resource elements depending upon the number of antennas employed by the eNodeB.

Further, E-UTRAN supports sub-frames with both conventional cyclical prefixes and extended cyclical prefixes. As such, FIGS. 1a-1c depict sub-frames with conventional cyclical prefixes with sub-frames having fourteen symbols. On the other hand, FIGS. 1d-1f depict sub-frames with extended cyclical prefixes with sub-frames comprising twelve symbols.

In E-UTRAN, the eNodeB does not explicitly inform the user equipment of the number of antennas and, in turn, the transmission diversity scheme. Instead, the user equipment can generally analyze the provided reference signals in an effort to determine the number of antennas and/or the transmission diversity scheme employed by the eNodeB. In general, reference signals are placed throughout a sub-frame, within the PBCH and otherwise, according to the number of transmit antennas at the base station. The reference signals are mainly intended to be used for channel estimation purposes. Regardless of a reference signal's location within the sub-frame, detecting the presence of a reference signal can allow user equipment to determine the number of transmit antennas at the base station. However, there is evidence that such a procedure is not reliable at the low signal-to-noise ratio conditions where the PBCH is designed to operate. Referring now to FIGS. 1a-1c, the PBCH is comprised of symbol #3 and symbol #4 of slot #0, and symbol #0 and symbol #1 of slot #1. In the single antenna configuration of FIG. 1a, symbol #4 of slot #0 and symbol #0 of slot #1 contain reference signals that provide antenna configuration information. Referring now to the two antenna configuration of FIG. 1b, symbol #4 of slot #0 and symbol #0 of slot #1 contain reference signals associated with the first and second antennas of the eNodeB designated R0 and R1, respectively. Similarly, referring to the four antenna configuration of FIG. 1c, symbol #4 of slot #0 and symbols #0 and #1 of slot #1 contain reference signals associated with four antennas, namely, R0, R1, R2, and R3. By analyzing the reference signals, the user equipment can attempt to determine the number of antennas and, in turn, the transmission diversity scheme employed by the eNodeB, such as space-frequency block codes (SFBC) used by two antenna eNodeBs and frequency switched transmit diversity (SFBC-FSTBC) used by four antenna eNodeBs. The user equipment can similarly analyze the PBCH or the reference signals in the sub-frames with extended cyclical prefixes of FIGS. 1d-1f in an effort to determine the antenna configuration information, except that the PBCH in the extended cyclical prefix cases is associated with symbol #3 of slot #0 and symbols #0, #1, and #2 of slot #1.

However, while antenna configuration information can be derived from the reference signals, the user equipment is, at least initially, not aware of the antenna configuration and/or the transmission diversity scheme prior to receiving and demodulating the PBCH. Further, since the antenna configuration information is needed to properly demodulate data and control channels, data loss and latency can result if the user equipment incorrectly identifies the antenna configuration and/or the transmission diversity scheme or if the user equipment is slow in identifying the antenna configuration and/or the transmission diversity scheme. As a result, some user equipment is designed to make assumptions regarding the antenna configuration and/or transmission diversity scheme. These assumptions of antenna configuration and/or transmission diversity scheme may be made prior to, or during demodulation of the PBCH and may not always be correct. In this regard, user equipment may reach an assumption regarding the antenna configuration and/or transmission diversity scheme based on a subset of the information in the PBCH. For example, in some instances, an early PBCH decoding scheme may be utilized which uses information gathered from the first of four bursts of information comprising the PBCH. Similarly, noise in the received signal may also affect the user equipment's assumption regarding an antenna configuration and/or transmission diversity scheme.

The error rate associated with the user equipment's assumption of the antenna configuration and/or the transmission diversity scheme or at least the adverse consequences which flow from an incorrect assumption can be exacerbated due to the conventional mapping of the PBCH within a sub-frame. For example, consider the PBCH of the sub-frames in FIG. 1b (for a two antenna base station) and FIG. 1c (for a four antenna base station). Note that the first three symbols of the PBCH are identical with respect to the reference signals, namely, symbols #3 and #4 of slot #0, and symbol #0 of slot #1. It is not until the final symbol of the PBCH that a difference in the antenna configuration can be ascertained as a result of the provision of R2 and R3 providing information regarding the third and fourth antennas, respectively. As such, the similarities of the PBCH for a two antenna configuration and a four antenna configuration can increase the error rate associated with the user equipment's assumption of the antenna configuration and/or the transmission diversity scheme or at least the adverse consequences which flow from an incorrect assumption.

Additionally, conventional diversity schemes for PBCH share large portions of signals. As such, an incorrect selection of a diversity scheme implemented to decode the PBCH can result in a proper decoding of the PBCH. The incorrect selection may then be used further which can result in substantial errors in communications. Under the conventional PBCH mapping this result can occur relatively frequently when considering that the various antenna configurations share a large number of resource elements.

Thus, in order to avoid or reduce the loss of data and communication latency, it would be desired to provide an improved technique for more reliably determining the antenna configuration and/or transmission diversity scheme of a network entity, such as a base station.

A method and apparatus are therefore provided in accordance with embodiments of the present invention to provide additional information relating to an antenna configuration and/or a transmission diversity scheme. As such, embodiments of the method and apparatus permit a recipient to reliably distinguish between a plurality of antenna configurations and/or transmission diversity schemes, thereby permitting the transmitted data to be more reliably demodulated and interpreted. Moreover, embodiments of the method and apparatus are configured to provide this additional information without transmitting any additional bits or otherwise adding to the overhead associated with the transmission of the data.

According to one aspect, a method and apparatus including a processor are provided for obtaining a bit mask based upon an antenna configuration and/or a transmission diversity scheme, and for then masking a plurality of bits to be transmitted with the bit mask to thereby impart information regarding the antenna configuration and/or the transmission diversity scheme. The plurality of bits which are masked may be bits of a physical broadcast channel. In one embodiment, for example, the plurality of bits which are masked may be a plurality of cyclic redundancy check (CRC) bits. In one embodiment, the bit mask is sufficient to permit at least three different antenna configurations or transmission diversity schemes to be uniquely distinguished.

In another aspect, a method and apparatus including a processor are provided for analyzing a plurality of bits that were received to determine which one of a plurality of pre-defined bit masks has been applied to the bits, and for then determining an antenna configuration and/or a transmission diversity scheme based upon the respective bit mask that is determined to have been applied to the bits. The plurality of bits which are analyzed may be bits of a physical broadcast channel. In one embodiment, for example, the plurality of bits which are analyzed may be a plurality of CRC bits. In one embodiment, the bit mask is sufficient to permit at least three different antenna configurations or transmission diversity schemes to be uniquely distinguished.

In yet another aspect, a method and an apparatus including a processor are provided for mapping a plurality of symbols which comprise a physical broadcast channel to a plurality of resource elements. In this regard, predefined ones of the resource elements are reserved for reference signals indicative of an antenna configuration and/or a transmission diversity scheme. The method and apparatus of this aspect are further configured to map the plurality of symbols such that sufficient reference signals are included within the first two symbols of the physical broadcast channel to permit at least three different antenna configurations or transmission diversity schemes to be uniquely distinguished. In instances in which the physical broadcast channel is included in a sub-frame having first and second slots, the method and apparatus may be configured to map all of the symbols which comprise the physical broadcast channel in the second slot of the sub-frame. In one embodiment, the method and apparatus may be configured to map all of the symbols which comprise the physical broadcast channel to a plurality of contiguous symbols.

In a further aspect, a method and apparatus including a processor are provided for receiving a plurality of symbols which comprise a physical broadcast channel, and for then determining an antenna configuration and/or a transmission diversity scheme based upon differences in a physical broadcast channel due to reference signals included within the first two symbols of the physical broadcast channel. In this aspect, the method and apparatus are further configured to uniquely distinguish between at least three different antenna configurations or transmission diversity schemes based upon the reference symbols included within the first two symbols of the physical broadcast channel. In instances in which the physical broadcast channel is included in a sub-frame having first and second slots, the method and apparatus may be further configured to receive all of the symbols which comprise the physical broadcast channel in the second slot of the sub-frame. In one embodiment, the method and apparatus may be further configured to receive all of the symbols which comprise the physical broadcast channel in a plurality of contiguous symbols.

Embodiments of the present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. Indeed, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like reference numerals refer to like elements throughout.

FIG. 2 illustrates a block diagram of a mobile terminal 10 that would benefit from embodiments of the present invention. It should be understood, however, that a mobile telephone as illustrated and hereinafter described is merely illustrative of one type of mobile terminal (also known as user equipment) that would benefit from embodiments of the present invention and, therefore, should not be taken to limit the scope of embodiments of the present invention. While one embodiment of the mobile terminal 10 is illustrated and will be hereinafter described for purposes of example, other types of mobile terminals, such as portable digital assistants (PDAs), pagers, mobile computers, mobile televisions, gaming devices, laptop computers, cameras, video recorders, GPS devices and other types of voice and text communications systems, can readily employ embodiments of the present invention. Furthermore, user equipment that is not mobile may also readily employ embodiments of the present invention.

The system and method of embodiments of the present invention will be primarily described below in conjunction with mobile communications applications. However, it should be understood that the system and method of embodiments of the present invention can be utilized in conjunction with a variety of other applications, both in the mobile communications industries and outside of the mobile communications industries.

The mobile terminal 10 includes an antenna 12 (or multiple antennae) in operable communication with a transmitter 14 and a receiver 16. The mobile terminal 10 further includes an apparatus, such as a controller 20 or other processing element that provides signals to and receives signals from the transmitter 14 and receiver 16, respectively. The signals include signaling information in accordance with the air interface standard of the applicable cellular system, and also user speech, received data and/or user generated data. In this regard, the mobile terminal 10 is capable of operating with one or more air interface standards, communication protocols, modulation types, and access types. By way of illustration, the mobile terminal 10 is capable of operating in accordance with any of a number of first, second, third and/or fourth-generation communication protocols or the like. For example, the mobile terminal 10 may be capable of operating in accordance with second-generation (2G) wireless communication protocols IS-136 (time division multiple access (TDMA)), GSM (global system for mobile communication), and IS-95 (code division multiple access (CDMA)), or with third-generation (3G) wireless communication protocols, such as Universal Mobile Telecommunications System (UMTS) including UTMS Long Term Evolution (UTMS LTE), CDMA2000, wideband CDMA (WCDMA) and time division-synchronous CDMA (TD-SCDMA), with fourth-generation (4G) wireless communication protocols or the like.

It is understood that the apparatus such as the controller 20 includes means, such as circuitry, desirable for implementing audio and logic functions of the mobile terminal 10. For example, the controller 20 may be comprised of a digital signal processor device, a microprocessor device, and various analog to digital converters, digital to analog converters, and other support circuits. Control and signal processing functions of the mobile terminal 10 are allocated between these devices according to their respective capabilities. The controller 20 thus may also include the functionality to convolutionally encode and interleave message and data prior to modulation and transmission. The controller 20 can additionally include an internal voice coder, and may include an internal data modem. Further, the controller 20 may include functionality to operate one or more software programs, which may be stored in memory. For example, the controller 20 may be capable of operating a connectivity program, such as a conventional Web browser. The connectivity program may then allow the mobile terminal 10 to transmit and receive Web content, such as location-based content and/or other web page content, according to a Wireless Application Protocol (WAP), Hypertext Transfer Protocol (HTTP) and/or the like, for example.

The mobile terminal 10 may also comprise a user interface including an output device such as a conventional earphone or speaker 24, a microphone 26, a display 28, and a user input interface, all of which are coupled to the controller 20. The user input interface, which allows the mobile terminal 10 to receive data, may include any of a number of devices allowing the mobile terminal 10 to receive data, such as a keypad 30, a touch display (not shown) or other input device. In embodiments including the keypad 30, the keypad 30 may include the conventional numeric (0-9) and related keys (#, *), and other hard and/or soft keys used for operating the mobile terminal 10. Alternatively, the keypad 30 may include a conventional QWERTY keypad arrangement. The keypad 30 may also include various soft keys with associated functions. In addition, or alternatively, the mobile terminal 10 may include an interface device such as a joystick or other user input interface. The mobile terminal 10 further includes a battery 34, such as a vibrating battery pack, for powering various circuits that are required to operate the mobile terminal 10, as well as optionally providing mechanical vibration as a detectable output.

The mobile terminal 10 may further include a user identity module (UIM) 38. The UIM 38 is typically a memory device having a processor built in. The UIM 38 may include, for example, a subscriber identity module (SIM), a universal integrated circuit card (UICC), a universal subscriber identity module (USIM), a removable user identity module (R-UIM), etc. The UIM 38 typically stores information elements related to a mobile subscriber. In addition to the UIM 38, the mobile terminal 10 may be equipped with memory. For example, the mobile terminal 10 may include volatile memory 40, such as volatile Random Access Memory (RAM) including a cache area for the temporary storage of data. The mobile terminal 10 may also include other non-volatile memory 42, which can be embedded and/or may be removable. The non-volatile memory 42 can additionally or alternatively comprise an electrically erasable programmable read only memory (EEPROM), flash memory or the like. The memories can store any of a number of pieces of information, and data, used by the mobile terminal 10 to implement the functions of the mobile terminal 10. For example, the memories can include an identifier, such as an international mobile equipment identification (IMEI) code, capable of uniquely identifying the mobile terminal 10.

Referring now to FIG. 3, an illustration of one type of system that would benefit from embodiments of the present invention is provided. The system includes a plurality of network devices, such as mobile terminals 10 or other types of user equipment. As shown, one or more mobile terminals 10 may each include an antenna 12 for transmitting signals to and for receiving signals from a base site or base station (BS) 44, such as an eNodeB in E-UTRAN. The base station 44 may be a part of one or more cellular or mobile networks each of which includes elements required to operate the network, such as a mobile switching center (MSC) 46. As well known to those skilled in the art, the mobile network may also be referred to as a Base Station/MSC/Interworking function (BMI). In operation, the MSC 46 is capable of routing calls to and from the mobile terminal 10 when the mobile terminal 10 is making and receiving calls. The MSC 46 can also provide a connection to landline trunks when the mobile terminal 10 is involved in a call. In addition, the MSC 46 can be capable of controlling the forwarding of messages to and from the mobile terminal 10, and can also control the forwarding of messages for the mobile terminal 10 to and from a messaging center. It should be noted that although the MSC 46 is shown in the system of FIG. 2, the MSC 46 is merely an exemplary network device and embodiments of the present invention are not limited to use in a network employing an MSC.

BS 44 can utilize various antenna configurations and/or transmission diversity schemes. Antenna configurations can include BS 44 having one or more antennas that utilize various transmission diversity schemes. For example, in some embodiments, BS 44 can comprise a single transmit antenna. In other exemplary embodiments, BS 44 can comprise a two transmit antennas that can use space-frequency block codes (SFBC) as a transmission diversity scheme. In still other exemplary embodiments, BS 44 can comprise four transmit antennas that can use a SFBC frequency switched transmit diversity (FSTD) transmission diversity scheme.

In one embodiment, the MSC 46 can be coupled to a data network, such as a local area network (LAN), a metropolitan area network (MAN), and/or a wide area network (WAN). The MSC 46 can be directly coupled to the data network. In one typical embodiment, however, the MSC 46 is coupled to a gateway device (GTW) 48, and the GTW 48 is coupled to a WAN, such as the Internet 50. In turn, devices such as processing elements (e.g., personal computers, server computers or the like) can be coupled to the mobile terminal 10 via the Internet 50. For example, the processing elements can include one or more processing elements associated with a computing system 52, origin server 54, and/or the like, as described below.

The BS 44 can also be coupled to a signaling GPRS (General Packet Radio Service) support node (SGSN) 56. As known to those skilled in the art, the SGSN 56 is typically capable of performing functions similar to the MSC 46 for packet switched services. The SGSN 56, like the MSC 46, can be coupled to a data network, such as the Internet 50. The SGSN 56 can be directly coupled to the data network. In a more typical embodiment, however, the SGSN 56 is coupled to a packet-switched core network, such as a GPRS core network 58. The packet-switched core network is then coupled to another GTW 48, such as a GTW GPRS support node (GGSN) 60, and the GGSN 60 is coupled to the Internet 50. In addition to the GGSN 60, the packet-switched core network can also be coupled to a GTW 48. Also, the GGSN 60 can be coupled to a messaging center. In this regard, the GGSN 60 and the SGSN 56, like the MSC 46, may be capable of controlling the forwarding of messages, such as MMS messages. The GGSN 60 and SGSN 56 may also be capable of controlling the forwarding of messages for the mobile terminal 10 to and from the messaging center.

In addition, by coupling the SGSN 56 to the GPRS core network 58 and the GGSN 60, devices such as a computing system 52 and/or origin server 54 may be coupled to the mobile terminal 10 via the Internet 50, SGSN 56 and GGSN 60. In this regard, devices such as the computing system 52 and/or origin server 54 may communicate with the mobile terminal 10 across the SGSN 56, GPRS core network 58 and the GGSN 60. By directly or indirectly connecting mobile terminals 10 and the other devices (e.g., computing system 52, origin server 54, etc.) to the Internet 50, the mobile terminals 10 may communicate with the other devices and with one another, such as according to the HyperText Transfer Protocol (HTTP) and/or the like, to thereby carry out various functions of the mobile terminals 10.

Although not every element of every possible mobile network is shown and described herein, it should be appreciated that the mobile terminal 10 may be coupled to one or more of any of a number of different networks through the BS 44. In this regard, the network(s) may be capable of supporting communication in accordance with any one of a variety of communication protocols, such as one or more of a number of first-generation (1G), second-generation (2G), 2.5G, third-generation (3G), 3.90, fourth-generation (4G) mobile communication protocols or the like. For example, one or more of the network(s) can be capable of supporting communication in accordance with 2G wireless communication protocols IS-136 (TDMA), GSM, and IS-95 (CDMA). Also, for example, one or more of the network(s) can be capable of supporting communication in accordance with 2.5G wireless communication protocols GPRS, Enhanced Data GSM Environment (EDGE), or the like. Further, for example, one or more of the network(s) can be capable of supporting communication in accordance with 3G wireless communication protocols such as E-UTRAN or a UMTS network employing WCDMA radio access technology. Some narrow-band analog mobile phone service (NAMPS), as well as total access communication system (TACS), network(s) may also benefit from embodiments of the present invention, as should dual or higher mode mobile stations (e.g., digital/analog or TDMA/CDMA/analog phones).

The mobile terminal 10 can further be coupled to one or more wireless access points (APs) 62. The APs 62 may comprise access points configured to communicate with the mobile terminal 10 in accordance with techniques such as, for example, radio frequency (RF), Bluetooth (BT), infrared (IrDA) or any of a number of different wireless networking techniques, including wireless LAN (WLAN) techniques such as IEEE 802.11 (e.g., 802.11a, 802.11b, 802.11g, 802.11n, etc.), world interoperability for microwave access (WiMAX) techniques such as IEEE 802.16, and/or ultra wideband (UWB) techniques such as IEEE 802.15 and/or the like. The APs 62 may be coupled to the Internet 50. Like with the MSC 46, the APs 62 can be directly coupled to the Internet 50. In one embodiment, however, the APs 62 are indirectly coupled to the Internet 50 via a GTW 48. Furthermore, in one embodiment, the BS 44 may be considered as another AP 62. As will be appreciated, by directly or indirectly connecting the mobile terminals 10 and the computing system 52, the origin server 54, and/or any of a number of other devices, to the Internet 50, the mobile terminals 10 can communicate with one another, the computing system, etc., to thereby carry out various functions of the mobile terminals 10, such as to transmit data, content or the like to, and/or receive content, data or the like from, the computing system 52. As used herein, the terms “data,” “content,” “information” and similar terms may be used interchangeably to refer to data capable of being transmitted, received and/or stored in accordance with embodiments of the present invention. Thus, use of any such terms should not be taken to limit the spirit and scope of embodiments of the present invention.

As will be appreciated, by directly or indirectly connecting the mobile terminals 10 and the computing system 52, the origin server 54, and/or any of a number of other devices, to the Internet 50, the mobile terminals 10 can communicate with one another, the computing system, 52, the origin server 54, etc., to thereby carry out various functions of the mobile terminals 10, such as to transmit data, content or the like to, and/or receive content, data or the like from, the computing system 52, and/or the origin server 54, etc.

In order to provide various signaling information, a base station 44 may provide the user equipment 10 with sub-frames having a predefined or standardized format. In order to provide antenna configuration information to the user equipment in a manner that improves the reliability with which the user equipment determines the antenna configuration and/or the transmission diversity scheme of the base station, the base station and the user equipment may be configured in accordance with one embodiment of the present invention to transmit and receive, respectively, the PBCH that is mapped to resource elements within a sub-frame in a different manner than those depicted in FIGS. 1a-1f. In this regard, FIGS. 4a-4f depict diagrams of exemplary PBCH mapping for various antenna configurations and transmission diversity schemes according to embodiments of the present invention. The sub-frames of FIGS. 4a-4f include six physical resource blocks (PRBs) i.e. 72 sub-carriers which is 1040 kHz, included in sub-frame #0. Sub-frame #0 is comprised of two slots designated slot #0 and slot #1. Each slot can be comprised of a series of symbols which, in turn, are comprised of a plurality, e.g., seventy-two, resource elements and associated with a respective channel such as a physical downlink (or download) control channel (PDCCH), a physical downlink shared channel (PDSCH), a primary synchronization channel (P-SCH), a secondary synchronization channel (S-SCH), a physical broadcast channel (PBCH), and unused sub-carriers. The sub-frame of FIGS. 4a-4f also include reference signals, namely, R0, R1, R2, and R3 which provide information regarding a first, second, third and fourth antennas of the base station. Further, FIGS. 4a-4c depict exemplary sub-frames with cyclical prefixes having a normal length where the sub-frame can comprise fourteen OFDM symbols. On the other hand, FIGS. 4d-4f depict exemplary sub-frames with extended cyclical prefixes where the sub-frame can comprise twelve OFDM symbols.

The PBCH in the sub-frames of FIGS. 4a-4f can be used to detect antenna configuration information for a base station, which can include the number of antennas utilized by the base station and/or the transmission diversity scheme utilized by the base station. The PBCH in the sub-frames of FIGS. 4a-4f can facilitate detecting antenna configuration and/or transmission diversity schemes by mapping symbols within the PBCH such that sufficiently different reference signal placements, or locations, occur across the mappings for different antenna configurations. In some embodiments, sufficiently different reference signal placements occur across the mappings for different antenna configurations can occur within the first two symbols of the PBCH. As discussed above in conjunction with FIGS. 1a-1f, the conventional mapping of the PBCH to resource elements, or in other words the position of reference signals within the PBCH, can cause an increased error rate associated with the user equipment's determination of the antenna configuration and/or transmission diversity scheme of the base station because the conventional mapping results in identical reference signals being included in the first three PBCH symbols in instances in which the base station has either two or four antennas with reference signals associated with the additional antennas of a four antenna base station, i.e., R2 and R3, only being provided in the fourth PBCH symbol. As such, a PBCH mapping, in accordance with one embodiment of the present invention where the reference signals associated with various antenna configurations differ substantially in both time and frequency or at least more so than the conventional mapping, can result in a decreased error rate associated with the user equipment's determination of the antenna configuration and/or transmission diversity scheme of the base station. In particular, PBCH mappings that are significantly different between, for example, a two antenna configuration and a four antenna configuration, can allow for the user equipment to more reliably and perhaps more quickly determine the antenna configuration and/or transmission diversity scheme of the base station. Various embodiments of the invention can generate a one-to-one relationship between a selected antenna configuration and a successful decoding procedure, preventing the propagation of incorrect antenna configuration selections. By increasing the differentiation between the symbols of the PBCH, the likelihood of incorrect antenna configurations providing successful decoding of the PBCH can be reduced. As such, the sub-frames of FIGS. 4a-4f provide an exemplary PBCH mapping that increases the differentiation between the PBCH mappings to resource elements over the conventional PBCH mappings without changing the reference signal structure due to the reference signals. The resulting increased differentiation can be identified in the initial PBCH symbols that are provided in accordance with various antenna configurations.

In some embodiments, the mapping of the PBCH can be implemented by a base station, such as BS 44, or other network entity or means. In some embodiments, user equipment, such as mobile terminal 10, or other means can utilize the PBCH mapping in obtaining the antenna configuration information, such as the number of antennas and/or transmission diversity scheme of a base station. In some embodiments, the user equipment can utilize the PBCH mapping to make multiple, parallel assumptions regarding the antenna configuration and multiple PBCH decoding trials in order to determine the correct antenna configuration.

Referring now to FIGS. 4a-4c, the differences in the symbols associated with the PBCH mapping of one embodiment associated with a normal cyclical prefix can be highlighted in comparison to a conventional mapping depicted in FIGS. 1a-1c. In FIGS. 4a-4c, the PBCH can utilize symbol #0 through symbol #3 of slot #1. In contrast to a conventional mapping, all symbols of the PBCH may be mapped into slot #1. In further contrast, all symbols of the PBCH may be mapped to contiguous symbols, such as, for example contiguous OFDM symbols. Note that the first symbol of the PBCH mapping for a normal cyclical prefix, namely symbol #0 of slot # 1, can cause PBCH mapping differences between the single antenna configuration of FIG. 4a and the multiple antenna configurations of FIG. 4b and FIG. 4c. This can be due to the placement, or location, of the reference signals within the symbols of the PBCH. As such, in some embodiments, the placement or location of the reference signals within the symbols of the PBCH can be used create increased diversity between the contents of the symbols of the PBCH. Accordingly, the increased diversity can assist in determining the antenna configuration of a base station. In some embodiments, the reference signals can have sufficiently different placements across different antenna configurations to permit each antenna configuration to be uniquely identified.

In the sub-frame with the normal cyclical prefix of FIG. 4a the first symbol of the PBCH map can contain only R0 reference signals which provide information regarding the first antenna. As a result, in instances where the PBCH mapping includes a first OFDM symbol that comprises only R0 reference signals, it can be determined that a single antenna configuration is being utilized. However, in the sub-frames of FIGS. 4b and 4c for two and four antenna configurations, respectively, the first symbol of the PBCH can not only contain R0 reference signals, but also R1 reference signals which provide information regarding the second antenna. As a result, in instances where the PBCH mapping includes a first OFDM symbol that comprises both R0 and R1 reference signals, it can be determined that a multi-antenna configuration is being utilized.

Further, the differentiation between the two antenna configuration, depicted in FIG. 4b, and the four antenna configuration, depicted in FIG. 4c, can also be identified by considering the second symbol, namely symbol #1 of slot #1, of the PBCH. In the sub-frame associated with the two antenna configuration of FIG. 4b the second symbol of the PBCH can contain no reference signals. As a result, in instances where the PBCH mapping includes a first OFDM symbol that indicates that a multi-antenna configuration, and includes a second OFDM symbol that comprises no reference signals, it can be determined that a two antenna configuration is being utilized. However, in the sub-frame associated with the four antenna configuration of FIG. 4c, the second symbol of the PBCH can contain R2 and R3 reference signals which provide information regarding the third and fourth antennas, respectively. As a result, in instances where the PBCH mapping includes a first OFDM symbol that indicates that a multi-antenna configuration, and includes a second OFDM symbol that comprises R2 and R3 reference signals, it can be determined that a four antenna configuration is being utilized.

Similarly, referring now to FIGS. 4d-4f, the differences in the symbols associated with the PBCH mapping of another embodiment associated with an extended cyclical prefix can be highlighted in comparison to a conventional mapping depicted in FIGS. 1d-1f. As described above in conjunction with FIGS. 4a-4c, the reference signals in the first symbol of the PBCH permit a single antenna configuration to be distinguished from a multiple antenna configuration, while the reference signals in the second symbol of the PBCH permit a two antenna configuration to be distinguished from a four antenna configuration.

As such, the PBCH mapping of FIGS. 4a-4f supported by network entities, such as base stations, and user equipment in accordance with one embodiment of the present invention provides substantially more differentiation between the different antenna configurations and/or transmission diversity schemes within the first two symbols of the PBCH when compared to the conventional PBCH mapping. In this regard, PBCH mapping associated with the sub-frames of FIGS. 4a-4f provide a different number of reference signals in the PBCH for each different antenna configuration. Additionally, in comparison to the conventional PBCH mapping depicted in FIGS. 1a-1f which provides differences only in the fourth PBCH OFDM symbol to distinguish a two antenna configuration from a four antenna configuration, it is noteworthy that the PBCH mapping according to embodiments of the invention incorporate a sufficient number of reference signals within the first two symbols of the PBCH to permit at least different antenna configurations and/or transmission diversity schemes to be uniquely distinguished.

Additionally, since the PBCH mapping according to one embodiment groups all of the OFDM symbols of the PBCH together, the user equipment can include a micro sleep mode. In the micro sleep mode, the user equipment can deactivate various functionalities, such as components of the receiving chain, e.g., analog to digital converter, mixer, oscillators, amplifiers or the like, such that the user equipment does not expend resources to receive symbols which the user equipment does not require. Further, the resource utilized to detect the PBCH can be switched on and off less frequently since the entire PBCH is grouped together with no interruption. As such switching may not take place instantaneously but take some time, causing some overhead on time. Grouping the entire PBCH together can thus eliminate one switching cycle and can reduce the total power on time of switched components by one overhead time per sub-frame.

FIG. 5 is a flowchart that describes of the operations associated with broadcast channel transmission and reception in accordance with an embodiment of the present invention having a PBCH mapping as described with respect to FIGS. 4a-4f, in accordance with an embodiment of the invention. The procedure of FIG. 5 can comprise mapping symbols to resource elements to generate a PBCH burst at 500, and transmitting the PBCH burst at 510. As also shown in FIG. 5, after transmission, user equipment can receive the PBCH burst at 520 and determine antenna configuration or transmission diversity at 530.

At 500, symbols can be mapped to resource elements. The symbols can be mapped by a base station, such as BS 44 or other means. In some embodiments, the symbols can be mapped to resource elements resulting in the generation of a PBCH burst. In some embodiments, a plurality of symbols can be mapped to a plurality of predefined resource elements, where the plurality of symbols comprises a PBCH. Predefined resource elements can be reserved for resource symbols where the location of the resource elements, for instance with respect to time and frequency, is indicative of an antenna configuration and/or a transmission diversity scheme. In some embodiments, the plurality of symbols can be mapped to a plurality of predefined resource elements in accordance with embodiments of the invention described with respect to FIGS. 4a-4f. Further, in some embodiments, the mapping can be defined such that the first two symbols of the PBCH can permit the identification of at least three different antenna configurations and/or transmission diversity schemes. In this regard, in some embodiments, the three different antenna configurations and/or diversity schemes can be associated with one, two and four antenna configurations in an exemplary E-UTRAN environment. Additionally, in some embodiments, the symbols can be mapped to a PBCH in a sub-frame having first and second slots. In this regard, in some embodiments, the plurality of symbols can be mapped to comprise the PBCH in the second slot of the sub-frame. Further, in some embodiments, the plurality of symbols can be mapped which to comprise the PBCH such that all of the symbols that comprise the PBCH are mapped to a plurality of contiguous resource elements.

At 510, a PBCH burst can be transmitted. The PBCH burst can be in the form of a plurality of symbols which comprise a PBCH. The PBCH burst can be transmitted by a base station, such as BS 44, or other means. In some embodiments, the PBCH burst can be transmitted in the form of four self-decodable bursts. In some embodiments, transmission of the PBCH burst can include mapping the resource elements reserved for the PBCH and sending the PBCH burst over an air interface according to the antenna configuration and the transmission diversity scheme. Further, in some embodiments, channel coding, rate matching, modulation of the PBCH burst, and transmission diversity encoding can also be performed at 510.

At 520, user equipment, such as mobile terminal 10, or other means can receive the PBCH burst. The PBCH burst can be in the form of a plurality of symbols which comprise a PBCH. In some embodiments, the PBCH burst can be received in the form of four self-decodable bursts.

At 530, an antenna configuration and/or transmission diversity scheme can be determined. The antenna configuration and/or transmission diversity scheme can be determined based upon reference symbols within a PBCH. In this regard, the symbols of the PBCH can be serially decoded. In some embodiments, decoding the PBCH can involve selecting a trial antenna configuration and/or transmission diversity scheme in order to decode the PBCH. In some embodiments, the antenna configuration and/or transmission diversity scheme can be determined based on the reference signal content of the received OFDM symbols that make up the PBCH. The result of decoding the PBCH can be compared to the sub-frames described with respect to FIGS. 4a-4f to determine the associated antenna configurations and transmission diversity schemes. In some embodiments, if a successful match is found between the decoded PBCH and the PBCH mappings in the sub-frames of FIGS. 4a-4f then a correct trial antenna configuration was selected by the user equipment. In this regard, a one-to-one relationship can be established between a trial antenna configuration selection and a successful decoding operation. Additionally, in some embodiments, the antenna configuration and/or transmission diversity scheme can be determined based upon the reference signals included within the first two symbols of the PBCH. Further, in some embodiments, the first two symbols of the PBCH can uniquely distinguish at least three different antenna configurations and/or transmission diversity schemes. In this regard, in some embodiments, the three different antenna configurations and/or diversity schemes can be determined that are associated with one, two and four antenna configurations in an exemplary E-UTRAN environment. Additionally, in some embodiments, the symbols of the received PBCH can be included in a sub-frame having first and second slots. In this regard, in some embodiments, the plurality of symbols comprising the received PBCH can be located in the second slot of the sub-frame. Further, in some embodiments, the plurality of symbols comprising the received PBCH can be arranged such that all of the symbols that comprise a PBCH with a plurality of contiguous resource elements.

In some embodiments, mappings can be provided where a sufficient difference in the mappings for different antenna configurations and/or transmission diversity schemes exist. Therefore, in embodiments where different or incorrect antenna configurations or diversity schemes are assumed, these mappings can reduce the risk that the PBCH can be decoded even with an incorrect assumption. As such, it can be beneficial if the reference signals are located rather early in the bit stream, for example, in the first OFDM symbol that carries PBCH. In this regard, most of the bits will not be associated correctly with a wrong hypothesis on antenna configuration and/or transmission diversity.

This is shown in the example below that includes a sequence of transmitted bits. The “R” within the sequence of bits indicates a position occupied by a reference signal transmitted by the associated antenna, and the numbers denote the bits in a numerical order. 1 ANT and 2 ANT denote a 1 or 2 antenna configuration respectively.

As can be seen, given a blind antenna configuration assumption, only bit 1 is interpreted correctly when the assumption on the antenna configuration is incorrect. Also note that bit 9 is not transmitted in the example two antenna bit sequence.

For comparison purposes only, a worst case mapping can be to locate the reference signals at the very end of the bit stream as indicated below.