Abstract:
The innovation relates to a system and/or methodology for the reduction of pilot power transmission in mobile communication systems. More specifically, the innovation relates to varying the transmit power of a pilot signal to increase the power available to other services, such as customer voice and data communication. In addition, reducing the transmit power of the pilot signal can reduce or militate against interference with the pilot signals of neighboring or nearby cells.

Description:
TECHNICAL FIELD 
     The subject invention relates generally to mobile communication systems, and more particularly to apparatus and methodologies for varying the transmission power of pilot signals for the management of user devices. 
     BACKGROUND 
     Optimization of network coverage and service quality are constant goals for wireless network operators. Superior coverage and service quality results in enhanced user experiences, greater throughput, and ultimately increased revenue. A couple ways to achieve superior coverage and service quality are through increasing the power available to customer voice and data communication services, and reducing the interference between neighboring cells. 
     Mobile communication systems typically require a pilot signal (also known as a beacon signal) to be transmitted from a base station in order to provide information to mobile user devices. The information is usually related to the expected signal strength a mobile device might receive if served by the base station, although other system information can be derived from the pilot signal as well. 
     One example communications standard, WCDMA/UMTS, transmits what is known as a Common Pilot Channel (CPICH). The pilot channel is transmitted at full power, with no provision for power control, typically, 6% of the base station power is allocated to the CPICH. This represents a large fraction of downlink transmit power that is not available for to support customer voice or data traffic. Unfortunately, current communication standards do not provide for any systems or methodologies for reducing the transmit power required for pilot or beacon signals. 
     SUMMARY 
     The following presents a simplified summary of the disclosure in order to provide a basic understanding of some aspects of the full written description. This summary is not an extensive overview of the disclosure. It is not intended to identify key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later. 
     In one embodiment, a wireless communication system, including a base station that transmits at least one pilot signal, and a beacon component that can vary the transmit power of the pilot signal is disclosed. In an additional embodiment, a method facilitating wireless communication is disclosed, including transmitting at least one pilot signal, and varying the transmit power of the pilot signal. In yet another embodiment, a system facilitating wireless communication is disclosed, including means for transmitting at least one pilot signal, and means for varying the transmit power of the pilot signal. 
     To the accomplishment of the foregoing and related ends, certain illustrative aspects are described herein in connection with the following description and the annexed drawings. These aspects are indicative, however, of but a few of the various ways in which the principles disclosed herein can be employed and is intended to include all such aspects and their equivalents. Other advantages and novel features will become apparent from the following detailed description when considered in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an exemplary multiple access wireless communication system in accordance with an aspect of the subject specification. 
         FIG. 2  illustrates a general block diagram of a communication system in accordance with an aspect of the subject specification. 
         FIG. 3  illustrates an exemplary wireless communication system in accordance with an aspect of the subject specification. 
         FIG. 4  illustrates an example graph of constant transmit power of a typical pilot signal in accordance with the subject specification. 
         FIG. 5  illustrates an example general component block diagram of a wireless network in accordance with the subject specification. 
         FIG. 6  illustrates an example graph of varying transmit power of a pilot signal using a predetermined sequence in accordance with an aspect of the subject specification. 
         FIG. 7  illustrates an example graph of varying transmit power of a pilot signal using a pseudo-random sequence in accordance with an aspect of the subject specification. 
         FIG. 8  illustrates an example methodology facilitating the reduction of pilot power transmission is shown in accordance with an aspect of the current specification. 
         FIG. 9  illustrates an approach that employs an artificial intelligence component which facilitates automating one or more features in accordance with an alternative specification. 
     
    
    
     DETAILED DESCRIPTION 
     The claimed subject matter is now described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the claimed subject matter. It may be evident; however, that such matter can be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing the claimed subject matter. 
     As used in this application, the terms “component” and “system” are intended to refer to a computer-related entity, either hardware, a combination of hardware and software, software, or software in execution. For example, a component can be, but is not limited to being, a process running on a processor, a processor, a hard disk drive, multiple storage drives (of optical and/or magnetic storage medium), an object, an executable, a thread of execution, a program, and/or a computer. By way of illustration, both an application running on a server and the server can be a component. One or more components can reside within a process and/or thread of execution, and a component can be localized on one computer and/or distributed between two or more computers. 
     Referring initially to the drawings,  FIG. 1  Referring now to  FIG. 1 , a wireless communication system  100  is illustrated in accordance with various embodiments presented herein. System  100  comprises a base station  102  that can include multiple antenna groups. For example, one antenna group can include antennas  104  and  106 , another group can comprise antennas  108  and  110 , and an additional group can include antennas  112  and  114 . Two antennas are illustrated for each antenna group; however, more or fewer antennas can be utilized for each group. Base station  102  can additionally include a transmitter chain and a receiver chain, each of which can in turn comprise a plurality of components associated with signal transmission and reception (e.g., processors, modulators, multiplexers, demodulators, demultiplexers, antennas, etc.), as will be appreciated by one skilled in the art. 
     Base station  102  can communicate with one or more mobile devices such as mobile device  116  and mobile device  122 ; however, it is to be appreciated that base station  102  can communicate with substantially any number of mobile devices similar to mobile devices  116  and  122 . Mobile devices  116  and  122  can be, for example, cellular phones, smart phones, laptops, handheld communication devices, handheld computing devices, satellite radios, global positioning systems, PDAs, and/or any other suitable device for communicating over wireless communication system  100 . As depicted, mobile device  116  is in communication with antennas  112  and  114 , where antennas  112  and  114  transmit information to mobile device  116  over a forward link  118  and receive information from mobile device  116  over a reverse link  120 . Moreover, mobile device  122  is in communication with antennas  104  and  106 , where antennas  104  and  106  transmit information to mobile device  122  over a forward link  124  and receive information from mobile device  122  over a reverse link  126 . In a frequency division duplex (FDD) system, forward link  118  can utilize a different frequency band than that used by reverse link  120 , and forward link  124  can employ a different frequency band than that employed by reverse link  126 , for example. Further, in a time division duplex (TDD) system, forward link  118  and reverse link  120  can utilize a common frequency band and forward link  124  and reverse link  126  can utilize a common frequency band. 
     Each group of antennas and/or the area in which they are designated to communicate can be referred to as a sector of base station  102 . For example, antenna groups can be designed to communicate to mobile devices in a sector of the areas covered by base station  102 . In communication over forward links  118  and  124 , the transmitting antennas of base station  102  can utilize beamforming to improve signal-to-noise ratio of forward links  118  and  124  for mobile devices  116  and  122 . This can be provided by using a precoder to steer signals in desired directions, for example. Also, while base station  102  utilizes beamforming to transmit to mobile devices  116  and  122  scattered randomly through an associated coverage, mobile devices in neighboring cells can be subject to less interference as compared to a base station transmitting through a single antenna to all its mobile devices. Moreover, mobile devices  116  and  122  can communicate directly with one another using a peer-to-peer or ad hoc technology in one example. 
     According to an example, system  100  can be a multiple-input multiple-output (MIMO) communication system. Further, system  100  can utilize substantially any type of duplexing technique to divide communication channels (e.g., forward link, reverse link, . . . ) such as FDD, TDD, and the like. Moreover, the system  100  can be a multiple-bearer system. A bearer can be an information path of defined capacity, delay, bit error rate, etc. Mobile devices  116  and  122  can each serve one or more radio bearers. The mobile devices  116  and  122  can employ uplink rate control mechanisms to manage and/or share uplink resources across the one or more radio bearers. In one example, the mobile devices  116  and  122  can utilize token bucket mechanisms to serve the radio bearers and to enforce uplink rate limitations. 
     Pursuant to an illustration, each bearer can have an associated prioritized bit rate (PBR), maximum bit rate (MBR) and guaranteed bit rate (GBR). The mobile devices  116  and  122  can serve the radio bearers based, at least in part, on the associated bit rate values. The bit rate values can also be employed to calculate queue sizes that account for PBR and MBR for each bearer. The queue sizes can be included in uplink resource requests transmitted by the mobile devices  116  and  122  to the base station  102 . The base station  102  can schedule uplink resources for mobile device  116  and  122  based upon respective uplink requests and included queue sizes. 
       FIG. 2  is a block diagram of an embodiment of a transmitter system  210  (also known as the access point) and a receiver system  250  (also known as access terminal) in a MIMO system  200 . At the transmitter system  210 , traffic data for a number of data streams is provided from a data source  212  to a transmitter (TX) data processor  214 . 
     In an embodiment, each data stream is transmitted over a respective transmit antenna. TX data processor  214  formats, codes, and interleaves the traffic data for each data stream based on a particular coding scheme selected for that data stream to provide coded data. 
     The pilot data is typically a known data pattern that is processed in a known manner and may be used at the receiver system to estimate the channel response. The multiplexed pilot and coded data for each data stream is then modulated (i.e., symbol mapped) based on a particular modulation scheme (e.g., BPSK, QSPK, M-PSK, or M-QAM) selected for that data stream to provide modulation symbols. The data rate, coding, and modulation for each data stream may be determined by instructions performed by processor  230 . 
     The modulation symbols for all data streams are then provided to a TX MIMO processor  220 , which may further process the modulation symbols (e.g., for OFDM). TX MIMO processor  220  then provides N T  modulation symbol streams to N T  transmitters (TMTR)  222   a  through  222   t . In certain embodiments, TX MIMO processor  220  applies beamforming weights to the symbols of the data streams and to the antenna from which the symbol is being transmitted. 
     Each transmitter  222  receives and processes a respective symbol stream to provide one or more analog signals, and further conditions (e.g., amplifies, filters, and upconverts) the analog signals to provide a modulated signal suitable for transmission over the MIMO channel. N T  modulated signals from transmitters  222   a  through  222   t  are then transmitted from N T  antennas  224   a  through  224   t , respectively. 
     At receiver system  250 , the transmitted modulated signals are received by N R  antennas  252   a  through  252   r  and the received signal from each antenna  252  is provided to a respective receiver (RCVR)  254   a  through  254   r . Each receiver  254  conditions (e.g., filters, amplifies, and downconverts) a respective received signal, digitizes the conditioned signal to provide samples, and further processes the samples to provide a corresponding “received” symbol stream. 
     An RX data processor  260  then receives and processes the N R  received symbol streams from N R  receivers  254  based on a particular receiver processing technique to provide N T  “detected” symbol streams. The RX data processor  260  then demodulates, deinterleaves, and decodes each detected symbol stream to recover the traffic data for the data stream. The processing by RX data processor  260  is complementary to that performed by TX MIMO processor  220  and TX data processor  214  at transmitter system  210 . 
     A processor  270  periodically determines which pre-coding matrix to use (discussed below). Processor  270  formulates a reverse link message comprising a matrix index portion and a rank value portion. 
     The reverse link message may comprise various types of information regarding the communication link and/or the received data stream. The reverse link message is then processed by a TX data processor  238 , which also receives traffic data for a number of data streams from a data source  236 , modulated by a modulator  280 , conditioned by transmitters  254   a  through  254   r , and transmitted back to transmitter system  210 . 
     At transmitter system  210 , the modulated signals from receiver system  250  are received by antennas  224 , conditioned by receivers  222 , demodulated by a demodulator  240 , and processed by a RX data processor  242  to extract the reserve link message transmitted by the receiver system  250 . Processor  230  then determines which pre-coding matrix to use for determining the beamforming weights then processes the extracted message. 
       FIG. 3  illustrates an exemplary wireless communication system  300  configured to support a number of users, in which various disclosed embodiments and aspects may be implemented. As shown in  FIG. 3 , by way of example, system  300  provides communication for multiple cells  302 , such as, for example, macro cells  302   a - 302   g , with each cell being serviced by a corresponding access point (AP)  304  (such as APs  304   a - 304   g ). Each cell may be further divided into one or more sectors (e.g. to serve one or more frequencies). Various access terminals (ATs)  306 , including ATs  306   a - 306   k , also known interchangeably as user equipment (UE) or mobile stations, are dispersed throughout the system. Each AT  306  may communicate with one or more APs  304  on a forward link (FL) and/or a reverse link (RL) at a given moment, depending upon whether the AT is active and whether it is in soft handoff, for example. The wireless communication system  300  may provide service over a large geographic region, for example, macro cells  302   a - 302   g  may cover a few blocks in a neighborhood. 
     The cells  302  can provide coverage via a plurality of networks, such as GSM/GPRS/Edge network (hereinafter referred to as “2G network”), and/or UMTS network (hereinafter referred to as “WCDMA coverage,” “3G network,” or simply as “3G”). The cells  304   a - 304   g  each transmit a pilot signal (e.g. pilot channel, beacon signal, etc.). The pilot signals are transmitted from the base stations to the UEs ( 306   a - 306   l ) to provide information, such as an expected signal strength, and so forth. Typically, the pilot signal is constantly transmitted at full power, without provisions for power control. For example, in a WCDMA/UMTS network more than 6% of the base station power is allocated for the pilot signal. It can be appreciated that this represents a large fraction of downlink transmit power that can be used for alternative services, such as customer voice or data traffic. In addition, since every base station transmits a pilot signal, depending on the terrain or environment, the pilot signals can be a source of interference for neighboring base stations. For example, the pilot signal transmitted by base station  304   d  can interfere with the pilot signals transmitted from the base stations  304   a  and  304   b , because the terrain may allow for the base station&#39;s  304   d  pilot signal to propagate into the transmission range of the neighboring base stations  304   a  and  304   b.    
       FIG. 4  is an example bar graph  400  illustrating the transmission power of a typical pilot signal. The bar graph  400  has a horizontal-axis (e.g. x-axis) representing time (T) and a vertical-axis (e.g. y-axis) that represents the transmission power (P) of the pilot signal at a given T. As previously discussed, typical pilot signals are transmitted at a constant power or full power (e.g. P) continuously. For instance, the example pilot signal shown in the graph  400  is transmitted at full power P from time T to nT, where n is an integer. 
     A transmission technique such as the one shown in the graph  400  can lead to a number of results. First, continuously transmitting the pilot signal at full power P, can reduce the overall power remaining for other functionality. For example, in a WCDMA/UMTS network, where there is only a single carrier per base station, the power used for the pilot signal is unavailable for additional or alternative services, such as customer voice or data service. Secondly, in a plurality of network types the pilot signals of multiple base stations can be transmitted on the same frequency, thereby causing interference to occur between pilot signals where the range extends into other cells (see  FIG. 3 ). 
       FIG. 5  illustrates an example wireless communication system  500  in accordance with one or more aspects of the subject innovation. The system  500  includes a base station  502 , and one or more UEs  504  ( 504   a - 504   d ). In operation, the base station  502  continuously transmits a pilot signal  506 . The UEs  504  seek, sniff, or otherwise detect the pilot signal  506  as required. The UEs  504  can derive system information from the pilot signal, such as an expected signal strength. For instance, when the UE  504   a  comes in range of the base station  502  it can determine the presence of the pilot signal  506 . Based on the pilot signal  506  the UE  504   a  can determine the expected signal strength from the base station  502 , and based on the expected signal strength determine whether to connect to the base station  502  or continue looking for additional connection points. 
     The base station  502  includes a beacon component  508 . The beacon component  508  controls the transmission of the pilot signal  506 . As previously discussed, typically pilot signals  506  are transmitted at a constant power or full power. However, the beacon component  508  can vary the power at which the pilot signal  506  is transmitted. The beacon component  508  can vary the transmission power of the pilot signal  506  based on a predetermined power transmit sequence (discussed infra). Also, the UEs  504  can have prior knowledge (e.g. built-in, firmware, etc.) of the transmission sequence that allows the UEs  504  to perform in the same manner as if the pilot signal  506  was transmitted at a constant level. 
     Additionally or alternatively, the beacon component  508  can encode the power transmit level (e.g. attenuation) in the pilot signal  506 . Wherein the UEs  504  can decode the power transmit level of the pilot signal  506 , and still achieve performance capabilities similar to that of a pilot signal  506  that is transmitted at a constant level. For example, the beacon component  508  can determine the power transmit level of the pilot signal  506  using a pseudo-random sequence, and encode the pseudo-random sequence in the pilot signal  506 . The UEs  504  can receive the pilot signal  506 , decode the psudo-random sequence, and follow along with the attenuation of the pilot signal  506 . It is to be appreciated that this is but one example of how the beacon component  502  can determine the power transmit level of the pilot signal  506 , and that a number of techniques are capable within the scope and spirit of the subject innovation. 
     Referring now to  FIG. 6  a bar graph  600  illustrating an example pilot signal&#39;s varying transmit power in accordance with an aspect of the present innovation is shown. The bar graph  600  has a horizontal-axis (e.g. x-axis) representing time (T) and a vertical-axis (e.g. y-axis) that represents the transmission power (P) of the pilot signal at a given T. In this example, the transmit power of the pilot signal is at full power at a time T. The power is decreased (by 0.25P) each T, wherein after 4T the transmit power returns to P and the sequence is repeated until a time nT, where n is an integer. 
     Turning to  FIG. 7 , an example bar graph  700  illustrating a pilot signal&#39;s varying transmit power in accordance with an aspect of the present innovation is shown. The bar graph  700  has a horizontal-axis (e.g. x-axis) representing time (T) and a vertical-axis (e.g. y-axis) that represents the transmission power (P) of the pilot signal at a given T. In this example, the transmit power of the pilot signal is at full power at a time T. The power is varied using a sequence, such as a pseudo-random sequence, wherein after 4T the transmit power returns to P and the sequence is repeated until a time nT, where n is an integer. 
     In view of the exemplary systems described supra, a methodology that may be implemented in accordance with the disclosed subject matter will be better appreciated with reference to the flow chart of  FIG. 8 . While for purposes of simplicity of explanation, the methodologies are shown and described as a series of blocks, it is to be understood and appreciated that the claimed subject matter is not limited by the order of the blocks, as some blocks may occur in different orders and/or concurrently with other blocks from what is depicted and described herein. Moreover, the illustrated blocks do not represent all possible steps, and not all illustrated blocks may be required to implement the methodologies described hereinafter. 
     Referring now to  FIG. 8 , an example methodology facilitating the reduction of pilot power transmission is shown in accordance with an aspect of the current innovation. At  802 , a sequence for varying the transmission power of a pilot signal is determined (discussed supra). For instance, the transmission power of the pilot signal can be varied according to a predetermined to sequence. Additionally or alternatively, the transmission power of the pilot signal can be varied using a pseudo-random sequence. At  804 , the transmit power of the pilot signal is determined according to the sequence determined at  802 . In addition, the pilot signal can be encoded with the sequence so that it can be decoded by one or more UEs that do not have prior knowledge of the sequence. 
     At  806 , the pilot signal is transmitted at the power level determined at  804 . As previously discussed, varying the transmission power can reduce interference with neighboring cells and/or save power that can be allocated for other uses. At  808 , the power saved by varying the transmit power of the pilot signal can be allocated for additional functionality, including but not limited to customer voice and/or data service. 
       FIG. 9  illustrates an approach  900  that employs an artificial intelligence (Al) component  902  which facilitates automating one or more features in accordance with the subject invention. The subject invention (e.g., in connection with inferring) can employ various Al-based schemes for carrying out various aspects thereof. For example, a process for varying the transmit power of a pilot signal be facilitated by artificial intelligence. 
     A classifier is a function that maps an input attribute vector, x=(x 1 , x 2 , x 3 , x 4 , xn), to a confidence that the input belongs to a class, that is, f(x)=confidence(class). Such classification can employ a probabilistic and/or statistical-based analysis (e.g., factoring into the analysis utilities and costs) to prognose or infer an action that a user desires to be automatically performed. For instance, depending on the implementation a confidence can be assigned to the set of criteria, and an inference can be made as to the criteria that should be used as triggers for adding dithering. 
     A support vector machine (SVM) is an example of a classifier that can be employed. The SVM operates by finding a hypersurface in the space of possible inputs, which hypersurface attempts to split the triggering criteria from the non-triggering events. Intuitively, this makes the classification correct for testing data that is near, but not identical to training data. Other directed and undirected model classification approaches include, e.g., naïve Bayes, Bayesian networks, decision trees, neural networks, fuzzy logic models, and probabilistic classification models providing different patterns of independence can be employed. Classification as used herein also is inclusive of statistical regression that is utilized to develop models of priority. 
     As will be readily appreciated from the subject specification, the subject invention can employ classifiers that are explicitly trained (e.g., via a generic training data) as well as implicitly trained (e.g., via observing user behavior, receiving extrinsic information). For example, SVM&#39;s are configured via a learning or training phase within a classifier constructor and feature selection module. Thus, the classifier(s) can be used to automatically learn and perform a number of functions, including but not limited to determining according to a predetermined criteria when to update or refine the previously inferred schema, tighten the criteria on the inferring algorithm based upon the kind of data being processed (e.g., primary versus secondary, static versus dynamic, . . . ), and at what time of day to implement tighter criteria controls (e.g., in the evening when system performance would be less impacted). 
     What has been described above includes examples of the invention. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the subject invention, but one of ordinary skill in the art may recognize that many further combinations and permutations of the invention are possible. Accordingly, the invention is intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the appended claims. Furthermore, to the extent that the term “includes” is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term “comprising” as “comprising” is interpreted when employed as a transitional word in a claim.