Patent Publication Number: US-2009239569-A1

Title: Transmission power reduction in interference limited nodes

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is related to and claims the priority of U.S. Provisional Patent Application No. 61/064,679, filed on Mar. 19, 2008, which is hereby incorporated by reference in its entirety. 
    
    
     FIELD 
     Certain embodiments of the present invention generally relate to communications, especially wireless communications. In particular, certain embodiments of the present invention relate to the downlink (DL) transmission of the Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (UTRAN) long term evolution (LTE). More specifically, certain embodiments of the present invention are related to the Third Generation Partnership Project (3GPP) LTE and about power reduction of Node B power in case of limited interference scenarios. 
     BACKGROUND 
     Wireless communication networks are well known and constantly evolving. For example, UMTS is one of the third-generation (3G) cell phone technologies. Currently, the most common form of UMTS uses wideband code division multiple access (W-CDMA) as the underlying air interface, as standardized by the 3GPP. 
     Currently, UMTS networks worldwide are being upgraded to increase data rate and capacity for downlink packet data. In order to ensure a further competitiveness of UMTS, various concepts for UMTS Long Term Evolution (LTE) have been investigated to achieve a high-data-rate, low-latency and packet optimized radio access technology. 
     The 3GPP LTE (Long Term Evolution) is the name given to a project within the Third Generation Partnership Project to improve the UMTS mobile phone standard to cope with future requirements. Goals of the project include improving efficiency, lowering costs, improving services, making use of new spectrum opportunities, and better integration with other open standards. The LTE project is not a standard, but it is expected to result in the new evolved release 8 of the UMTS standard, including mostly or wholly extensions and modifications of the UMTS system. 
     A characteristic of conventional so-called “4G” networks, including Evolved UMTS, is that they are fundamentally based upon transmission control protocol/internet protocol (TCP/IP), the core protocol of the Internet, with built-on higher level services such as voice, video, and messaging. 
     In wireless networks, there may be an optimum transmission power level from a Node B. With increased transmission power, the Node B may possibly provide increased transmission quality, but the increased power may result in undesired effects, such as increased interference with a neighboring Node B. Similarly, if the power is reduced too much, the system performance may be degraded. However, operators typically wish to reduce transmission power to conserve energy and resources. 
     With network planning tools or in an the operation actual network, the power of a Node B can be fine-tuned, and a signal-to-interference-plus-noise ratio (SINR) distribution can be collected from the fine tuning. Typically, operators may want the system to be as energy efficient as possible, so the transmission power is usually initially reduced and the SINR measured. Then, in simulations or during actual operation and management of a system, the transmission power may be increased to determine a minimum DL transmission power level that has acceptably similar performance as the original higher DL transmission power. Disadvantage of this fine tuning power setting method is that the system is sometimes operated with degraded performance until needed appropriate correction can be done. 
     SUMMARY 
     In one embodiment, the present invention is a method including receiving, at a device, information about interference noise. The method also includes, when the interference noise satisfied a predefined level, changing, by the device, the downlink transmission power level. 
     Another embodiment of the present invention is an apparatus. The apparatus includes a receiver configured to collect information about interference noise. The apparatus also includes a transmitter configured, when the interference noise satisfied a predefined level, to change the downlink transmission power level. 
     A further embodiment of the present invention is a computer readable storage medium encoded with instruction configured to cause a processor to perform a process. The process includes receiving information about interference noise. The process also includes, when the interference noise satisfied a predefined level, changing the downlink transmission power level. 
     Another embodiment of the present invention is a method. The method includes collecting and forwarding, by a device, information about interference noise. The method also includes, when the interference noise satisfied a predefined level, receiving, by the device, a downlink transmission having a changed power level. 
     An additional embodiment of the present invention is an apparatus. The apparatus includes a processor for collecting information about interference noise. The apparatus also includes a transmitter to forward information about interference noise. The apparatus further includes a receiver configured to, when the interference noise satisfied a predefined level, receive a downlink transmission having a changed power level. 
     A further embodiment of the present invention is a computer readable storage medium encoded with instruction configured to cause a processor to perform a process. The process includes collecting and forwarding information about interference noise. The process also includes, when the interference noise satisfied a predefined level, receiving a downlink transmission having a changed power level. 
     Another embodiment of the present invention is a method. The method includes defining, by a device, a maximum interference noise level. The method also includes receiving, at the device, measurements regarding interference noise levels in a plurality of cells. The method further includes classifying the cells. The method additionally includes calculating transmission power changes depending on the classification of the cells. The method also includes forwarding, by the device, commands to each class of cells to implement the transmission power changes. 
     Yet another embodiment of the present invention is an apparatus. The apparatus includes a receiver configured to receive measurements regarding interference noise levels in a plurality of cells. The apparatus also includes a processor configured to define a maximum interference noise level, to classify the cells, and to calculate transmission power changes depending on the classification of the cells. The apparatus further includes a transmitter configured to forward commands to each class of the cells to implement the transmission power changes. 
     An additional embodiment of the present invention is a computer readable storage medium encoded with instruction configured to cause a processor to perform a process. The process includes defining a maximum interference noise level. The process also includes receiving measurements regarding interference noise levels in a plurality of cells. The process further includes classifying the cells. The process additionally includes calculating transmission power changes depending on the classification of the cells. The process also includes forwarding commands to each class of cells to implement the transmission power changes. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
       For proper understanding of the invention, reference should be made to the accompanying drawings, wherein: 
         FIG. 1A  is a grid depicting a multiple sector communications network in accordance with embodiments of the present invention; 
         FIG. 1B  is a high level schematic diagram of a wireless cell system in accordance with embodiments of the present invention; 
         FIG. 2A-2B  depicting exemplary performance loss from transmission power reductions in accordance with embodiments of the present invention; 
         FIGS. 3 and 6  depict steps in methods for reducing transmission power in accordance with embodiments of the present invention; 
         FIGS. 4 and 5  depicts process flow diagrams reducing transmission power in accordance with embodiments of the present invention; and 
         FIG. 7  is a high-level, schematic diagram that depicts components of a communications system in accordance with embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION  
     Certain embodiments of the present invention provide a procedure in which a measurement to avoid going into degraded performance by measuring in advance that optimum setting is achieved. 
     Referring now to  FIG. 1A , a network layout  100  having multiple sectors  101  of various types (see three different shadings) is depicted. In particular, the network layout  100  can be configured with 3 different types of sectors  101  on a hexagonal grid, such that identical types of sectors do not come into contact. In  FIG. 1A , each of the sectors  101  is designated by a numerical identifier (I) such that I (mod 3)≡1, 2, or 3, and two sectors (identified by I 1  and I 2 ) of the same type have I 1 (mod 3)≡I 2 (mod 3). Analysis of a LTE downlink (DL) system in limited interference scenarios often does not show gains by increasing the Node B transmission power. To the contrary, if the Node B transmission power is too high for the deployment scenario, the transmission can be reduced without loss in system performance. The hexagonal representation is used as an example for modeling, explanation and simulation. Real world applications can create cell shapes of non-hexagonal nature. The applied and described methodology discussed herein can work in a similar manner as described for the hexagonal cell shape example. Thus, the hexagonal representation should be viewed as an illustrative example, rather than as the only way that the real-world application of various embodiments of the present invention may be implemented. Thus  FIG. 1A  simply provides one example implementation. 
     As depicted in chart  200  in  FIG. 2A , the downlink signal to interference-plus-noise ratio (DL SINR) distribution in a sector often does not significantly change when DL transmission power is reduced to a certain degree. As with  FIG. 1A ,  FIG. 2A  provides simply an example embodiment. The calculation results depicted in chart  200  in  FIG. 2  are based upon the network  101  depicted in  FIG. 1A  having cells with 3 sectors on a hexagonal grid and with an inter-site distance of 500 m. The results depicted in table  200  further assumed a receiver noise figure of 9 dB, a bandwidth of 10 MHz, and no penetration loss. For the given example, the DL transmission power can be reduced from 46 dBm (curve  210 ), to 40 dBm (curve  220 ) and then to 34 dBm (curve  230 ). At 30 dBm (curve  240 ), the power reduction would harm the system performance as depicted by the degraded resulting SINR distribution of curve  240 . From this result, it can be seen that a technical challenge for self-optimizing the DL transmission power to minimize power consumption in the Node B can be to decide to what degree the DL transmission power can be reduced without harming the system performance. Referring to  FIG. 2B  (which like the other figures merely illustrates an example embodiment), an enlarged portion  201  of the chart  200  depicts in greater detail the relative similarity in the downlink signal to interference-plus-noise ratio (DL SINR) distributions of curves  210 ,  220 , and  230  versus the curve  240 . 
     Referring now to  FIG. 1B  (which, again, is merely one example embodiment), a UMTS cell  102  in accordance with an example embodiment of the present invention is generally described. In particular, the UMTS cell  102  typically can include one or more Node Bs  110  (known in the LTE as enhanced Node B or eNB) that define one or more sectors  101 , and multiple user equipments (UE)  120  associated with one or more of the cells  102 . The radio interface between the UE and the Node-B can be referred to as Uu  130 . 
     The Node B  110 , also known as a BTS (base transceiver station) in GSM, typically uses wideband code division multiple access (WCDMA) as air transport technology, although this is merely an illustration for the purposes of discussion. The Node B can contain radio frequency transmitter(s) and the receiver(s) used to communicate directly with the mobiles, which can move freely around it or can be in fixed locations in certain embodiments. In this type of cellular network, the UE  120  usually cannot communicate directly with each other but have to communicate via with the Node B  110 . 
     Traditionally, the Node B  110  has minimum functionality and is controlled by an RNC (Radio Network Controller). However, this assumption is changing, for example, with the emergence of High Speed Downlink Packet Access (HSDPA), where some logic (e.g. retransmission) is handled on the Node B for lower response times. 
     The utilization of WCDMA technology in the LTE can permit cells belonging to the same or different Node Bs  110  and even controlled by different RNCs to overlap and still use the same frequency (in fact, the whole network can be implemented with just one frequency pair) to achieve soft handovers between the cells. 
     Since WCDMA often operates at higher frequencies than GSM, the cell range can be considerably smaller compared to GSM cells, and, unlike in GSM, the size of the cells may not be constant, in a phenomenon known as cell breathing. This configuration typically requires a larger number of Node-Bs and careful planning in 3G (UMTS) networks. However, the power requirements on the Node Bs  110  and the UE  120  (user equipment) are usually much lower. Optimization of this power, for example in the DL transmissions, is described below using example embodiments. 
     The Node B  110  typically includes at least one antenna  112  connected to several components, including power amplifiers and digital signal processors (not depicted). The Node B  110  can serve several cells  101 , also called sectors, depending on the configuration and type of antenna. 
     Continuing with  FIG. 1B , the UE  120  roughly corresponds to the mobile station in GSM systems and can be any device used directly by an end user to communicate. For example, the UE  120  can be various components that connect to a wireless network to exchange data, including a personal data assistant (PDA), various wireless device, a hand-held telephone, a card in a laptop computer, or other device. Although the UE  120  can be a mobile device, there is no specific requirement that a UE  120  be actually mobile. The UE  120  can connect to the base station, the above-described Node-B as specified in the 25-series of specifications, and roughly corresponds to the mobile station in GSM systems. 
     The UE  120  typically handles the tasks towards the core network, including: mobility management, call control, session management, and identity management. Generally, the corresponding protocols are transmitted transparently via a node-B  110 , such that the node-B  110  does not change, use or understand the protocol information. The UMTS back-end can become accessible via a variety of means, such as a GSM UMTS radio network (GERAN, UTRAN, and E-UTRAN), WiFi, UMB and WiMAX. For example, users of non-UMTS radio networks may be provided with an entry-point into the IP network, with different levels of security depending on the trustworthiness of the network being used to make the connection. Users of GSM/UMTS networks may use an integrated system where all authentication at every level of the system is covered by a single system, while users accessing the UMTS network via WiMAX and other similar technologies would handle the WiMAX connection one way: for example, authenticating themselves via a media access control (MAC) address or electronic serial number (ESN) address, and the UMTS link-up another way. 
     In LTE Release 8, an air interface called the Evolved Universal Terrestrial Radio Access (E-UTRA) could be used by UMTS operators deploying wireless networks. While the E-UTRA is still being refined, the current E-UTRA systems use OFDMA for the downlink (tower to handset) and Single Carrier FDMA (SC-FDMA) for the uplink and employs multiple-input/multiple-output (MIMO) with up to four antennas per station. The channel coding scheme for transport blocks is turbo coding and a contention-free quadratic permutation polynomial (QPP) turbo code internal interleaver. 
     The use of OFDM (a system where the available spectrum can be divided into thousands of very thin carriers, each on a different frequency, each carrying a part of the signal) can enable E-UTRA to be much more flexible in its use of spectrum than the older CDMA based systems used in the 3G protocols. CDMA networks typically require large blocks of spectrum to be allocated to each carrier to maintain high chip rates and thus maximize efficiency. OFDM has a link spectral efficiency that is greater than CDMA, and when combined with modulation formats such as 64QAM and techniques as MIMO, E-UTRA is typically more efficient than W-CDMA with HSDPA and HSUPA. 
     Referring now to  FIG. 3  (which is merely an illustration of example embodiments), certain embodiments of the present invention relate to a DL transmission power optimization method  300  that can include measuring an interference limitation in step  310 . It should be remembered that  FIG. 3  just illustrates certain illustrative embodiments. For example, a quotient of [I+N]/N, where N is a noise measurement at a UE, may be determined in step  310  and reported from the UE to the serving Node B in step  320 . 
     Data obtained as performance data may include, for example, cell load and/or information on whether an interference or noise limitation is prevailing in a particular cell. The impact on user and cell performance indicators can be traced in a system and the system can take countermeasures when degradation is detected. The countermeasures can include reducing downlink transmit power and cell switch off, which should be considered a special case example of reducing transmit power for the purposes of the discussion found herein. 
     The calculation of noise power (or thermal noise) N at the UE including the UE receiver noise figure NF can be done using equation 1. 
         N= 10*log 10( BW )+ N   0   +NF    (Eq. 1) 
     where BW is the bandwidth in Hz, N 0 =−173.93 dBm/Hz, and NF typically is known by the manufacturer of the UE. The NF can be pre-stored in memory in the UE or a worst case value can be signaled by network and received at the UE. Alternatively, NF may be a predefined estimated value that is used for any UE, regardless of equipment. For example, NF=9 dB is assumed in LTE standardization simulations. 
     Continuing with  FIG. 3 , the serving Node B can make a long term statistic in step  330  using the received noise information and can determine whether to reduce DL transmission power. For example, in step  330 , if [I+N]/N greater or much greater than 1 or, even more general, if [I+N]/N&gt;k, where k is signaled to the Node Bs for most of the measurements then DL transmission power can be reduced for this Node B. Another embodiment of this approach to making a long term statistic can be that the UE only sends noise information if power reduction is possible without degradation from the specific UE point of view, e.g. only if [I+N]/N&gt;k. This has the advantage that the number of transmitted measurements from the UE to the Node B can be reduced and can be fine-tuned by a parameter signaled from Node B. 
     Continuing with  FIG. 3 , however, if there is no similar action (e.g. power reduction or antenna tilting) in the surrounding Node Bs, the coverage area of the other Node Bs can increase, leading to handovers and impact on load balancing. Therefore it may be beneficial to coordinate the power change in step  340 . For example, the change can be coordinated by a central OAM entity  111  and power reduction may be performed at the same time and with the same power reduction step in a cluster of adjacent cells  102 , thereby achieving the above-described desired power reduction according to the above-described criteria. Another embodiment of this coordination can be that the Node B X2 interface can be used to coordinate the power reduction (or boosting) step in time and frequency domain. The X2 interface can be an interface connecting Node Bs and can permit, for example, signaling of information between neighboring Node Bs. 
     It is possible that cells adjacent to the cluster of power-reducing cells from steps  310 - 340 , cannot reduce their own power. For example, these adjacent cells may be noise-limited. Consequently, the coverage area for these non-reducing cells can increase, leading to handovers and impact on load balancing. Therefore load indicators of these adjacent cells can be optionally be tracked in step  350  and reported, for example to the OAM entity  111 . The power reduction may be altered or even abandoned, the transmission power reverting again in step  320  to original settings, for example, if load indicators are above a certain threshold or if an overload is indicated. 
     Referring back to  FIG. 1A , as a consequence of this and other factors, it may be possible to have system  100  have different power reduction levels at different groups of cells  101 . For example, in one implementation, cells at the center of a cluster have higher power reduction, with lower reduction levels toward the edge of the system because as such a power transmission gradient would help to prevent large differences in coverage area. 
     In general, the noise-limitation (e.g., when [I+N]/N≈1) determined in step  330 , typically occurs in the cell center and, in the case of coverage holes, also on the cell edges. The above-described calculations from step  330  can also be used for coverage hole detection if the statistics of [I+N]/N are confined to measurements related to the cell edges. For example, the Node B  110  may use the last measurements of a UE  120  before a handover or measurements from UEs with large timing advance (TA). By taking the statistics over all measurements and over the subset of cell edge measurements, each cell can detect in step  360 , whether that cell operates interference-limited (IL), noise limited in the cell center (NL c ), or noise-limited in the cell edges (NL e ), where the superset NL includes both noise-limited in cell center NL c  and edges NL e . 
     Another embodiment of what is described above can be to detect an interference-limitation (e.g., when [I+N]/N&gt;&gt;1) instead of noise-limitation. Thus, interference reduction can be accomplished by adapting transmit power, adapting antenna tilt, and/or cell switch on/off, all while maintaining required cell and user performance, as well as network stability. 
     A large amount of noise-limited measurements at the cell edges can be an indicator of potential coverage holes. If such an event has been detected, countermeasures can be taken. For example, a Node B can increase transmission power if the power has been reduced previously, adapt antenna tilting or inform OAM entities to indicate potential coverage shortage. 
     Therefore, each Node B in step  360  can optionally report an indication about its status with respect to interference or noise-limitation to the central OAM entity. The OAM entity can then determine the cells involved in the power reduction, individual power reduction targets, as well as configure and coordinate the power reduction procedure in a way that identical power reduction steps may be performed synchronously (or approximately simultaneously) at all involved Node Bs. 
     In this way, although the above description focuses on power reduction, it should be appreciated that power increases can be managed in the same way. For example, in step  330 , by carefully monitoring the new network status and based on several triggers, DL transmission power increases can be triggered and executed as well. 
     Likewise, although the above description focuses on power reduction of the whole Node B transmission power, it should be appreciated that power reduction and power boosting can be managed on sub-carrier or units of multiple sub-carriers. This means that at the same time (in a time and frequency coordinated way) sub-carriers of neighboring Node Bs are increased, whereas other sub-carriers are reduced and others are unchanged in power. With this embodiment for the decoding of the DL signal, the power profile can be signaled to the UE if multiple sub-carriers scheduled to a UE have different power settings or scheduler may be restricted to schedule UEs only on sub-carriers with the same or very similar power settings. 
     Referring now to  FIG. 4 , a process flow diagram  400  in accordance with certain embodiments of the present invention is now presented. In particular, the flow diagram  400  depicts the interaction between a Node B  410  and a UE  420 . The UE  420  may forward interference limitation data  440 . Typically, the interference limitation data  440  is sent as part of a data request message from the UE  420 . The Node B  410  can use this data from UE  420  to determine a DL transmission power level. The Node B  410  may forward a message  450  to coordinate the DL transmission power level with other Node Bs  430 . The Node B  410  can then create and forward a downlink message  460  to the UE  420 . In response to the DL message  460 , the UE  420  can forward to the Node B  410  additional performance measurements  470  regarding the impact from the change in the DL transmission power levels. 
     Referring now to  FIG. 5  (which, like the other figures, merely illustrates an example embodiment), a process flow diagram  500  in accordance with other embodiments of the present invention is now presented. In particular, the flow diagram  400  depicts the interaction between an OAM Entity  510 , a UE  520 , a local Node B  530  and another Node B  540  associated with another cell. The UE  520  in the cell may forward a DL request  550  to the local Node B  530  currently associated with the LE, and this DL request  550  can include interference limitation data. The local Node B  530  can then forward the interference limitation data  560  to the OAM entity  510 . The OAM entity  510  can use this data  560  to determine appropriate transmission power levels and can forward control signals  570  to the local Node B  530  and another Node B  540  to coordinate the transmission power levels. The Node B  530  can then create and forward a downlink message  580  to the UE  520 . In response to the DL message  580 , the UE  520  can forward to the local Node B  530  additional performance measurements  590  regarding the impact from the change in the DL transmission power levels. The local Node B  530  and the other Node B  540  may then forward the performance measurement  595  to the OAM entity  510  to reassess the change(s) in transmission power levels. 
     Thus, it can be seen that noise measurement can typically be performed at the UEs. Then, statistics of measurements can be collected in the Node B. The power of neighboring Node Bs which are interference limited may be synchronously reduced, and this reduction may be optionally controlled by a central OAM element. 
     Referring now to  FIG. 6 , a transmission power reduction method  600  in accordance with another embodiment of the present invention is now presented, but is just an example embodiment. In step  610 , threshold conditions are predefined. For example, a central OAM entity may signal the threshold k to the Node Bs. The Node Bs may collect statistics of interference limitation measurements and then report back to the OAM entity their status as either IL, NL c , or NL e , in step  620 . 
     Continuing with  FIG. 6 , the OAM entity may exclude certain cells from power reductions. For example, cells with status NL e  and their neighbors can be excluded in step  630  from further power reduction procedure since there is a risk of coverage holes that may be worsened by further power reductions. In step  640 , the remaining cells can be classified. For example, in step  640 , the OAM entity may detect the largest cluster of adjacent cells with status IL (and without neighbors of status NL e  as explained above), and neighboring cells of the cluster are, hence, NL c  and their load status is checked. 
     In step  650 , the power changes can be calculated depending on the classification of the cells. For example, in step  650 , a power reduction profile across the cell cluster may be optionally calculated to determine the maximum power reduction in each cell. It should be appreciated that many potential transmission power changing algorithms are conceivable. However, to minimize the impact on load and unnecessary handovers (HO), the maximum power reduction can typically be emphasized towards the edge cells of the cluster in step  650 , especially if there is already a significant load in the neighboring cells. In this way, in order to minimize impact on coverage area, a gradual increase in transmission power towards the cluster center may result. 
     In step  660 , after the power reduction profile is calculated, the OAM entity can configure each Node B by forwarding parameters such as maximum power reduction level, the starting time of the power reduction, the step size, and the time interval between power reduction steps. The Node B can then implement the configuration commands from the OAM entity in step  670 . In step  670 , all Node Bs can start synchronously to reduce the power until the individual maximum power reduction is reached to achieved minimum fluctuations in the coverage area without unnecessary HOs. 
     Continuing with  FIG. 6 , the OAM entity in step  680  can monitor the ongoing interference status reports and load reports and can trigger an inverse operation (power increase) similarly to what is described above. 
     In some implementations, measurements and/or the power reduction in method  600  could be restricted to a sub-band of the total bandwidth, e.g., to certain resource blocks. In this embodiment, the Node Bs are additionally configured in step  660  about the sub-band that is subject to the transmission power change, such as to identify the specific resource blocks to measure/reduce power. For example, network status can be probed with respect to a limited bandwidth in steps  660 - 670  before the procedure is repeated with more resource blocks, such as to determine the effect of a limited change and to later extend the change to the whole bandwidth. For example, a traffic scheduler could schedule background traffic while doing the probing power reduction, thus minimizing the impact on end user perception during the probing phase. 
     As depicted in  FIG. 7 , each of the UE  710  in a cell may include a processor  711 , memory  712 , and input and output devices  713 - 714 . The UE  710  may further include software  715  and related hardware  716  for performing the functions related to forming and broadcasting performance measurements, as discussed elsewhere herein. For example, the UE  710  may monitor, store, and report noise measurements to the Node B  720 . Thus, the processing of the interferences measurements may be performed and forwarded transmitted, as needed by circuitry in the hardware  716  or software  715 . 
     Likewise, the Node B  720  may include a processor  721 , memory  722 , and input and output devices  723 - 724 . The Node B  720  may further include software  725  and related hardware  726  for performing the functions related to calculation of the interference measurements and the resulting changes in transmission power levels. For example, the Node B  720  may include logic in the hardware  726  or the software  725  for calculating an interference limitation and implementing a corresponding change in transmission power levels for a particular UE  710  or for all of the UEs  710  in a cell. 
     Likewise, an OAM entity  730  may include a processor  731 , memory  732 , and input and output devices  733 - 734 . The OAM entity  730  may further include software  735  and related hardware  736  for performing the functions related to a calculation of changes in transmission power levels for multiple Node Bs  720  and for coordinating the changes in transmission power levels. For example, the OAM entity  730  may include logic in the hardware  736  or the software  735  for calculating and implementing a corresponding change in transmission power levels for a particular Node B  720  or for multiple Node Bs  720  in multiple cells. 
     When a device, such as a UE, a Node B, or an OAM, is configured to perform a method, one way in which it can be configured to perform the method is through the use of software embodied in a computer-readable medium, such as a computer-readable storage medium. 
     In one embodiment, a method includes collecting and forwarding, by a device, information about interference noise. The method also includes, when the interference noise satisfied a predefined level, receiving, by the device, a downlink transmission having a changed power level. 
     In the method, the transmission power level can be decreased when the interference noise is above a predefined value. Furthermore, the transmission power level can be increased when the interference noise is below a predefined value. The method can also include re-measuring the interferences levels following the first transmission power change and forwarding the re-measured interference levels. In the method, it can be that only a portion of the transmission bandwidth is changed. 
     Another embodiment of the present invention is a computer readable storage medium encoded with instruction configured to cause a processor to perform a process. The process can be the above-described method in any of its varying embodiments. 
     A further embodiment of the present invention is an apparatus including a processor for collecting information about interference noise. The apparatus also includes a transmitter to forward information about interference noise. The apparatus further includes a receiver configured to, when the interference noise satisfied a predefined level, receive a downlink transmission having a changed power level. 
     In the apparatus, the receiver can be configured to receive a downlink transmission having a decreased transmission power level when the interference noise is above a predefined value. Also, the receiver can be configured to receive a downlink transmission having an increased transmission power level when the interference noise is below a predefined value. The processor can be configured to re-measure interferences levels following the first transmission power change and wherein the transmitter is configured to forward the new interferences levels. It can be that only a portion of the transmission bandwidth is changed. 
     An additional embodiment of the present invention is a method including defining, by a device, a maximum interference noise level. The method also includes receiving, at the device, measurements regarding interference noise levels in a plurality of cells. The method further includes classifying the cells. The method additionally includes calculating transmission power changes depending on the classification of the cells. The method also includes forwarding, by the device, commands to each class of cells to implement the transmission power changes. 
     The method can also include monitoring, by the device, the interference noise levels in the cells. The classification can include excluding certain cells having interference noise level that exceed the maximum. It can be that only a portion of the transmission bandwidth is changed. 
     Another embodiment of the present invention is a computer readable storage medium encoded with instruction configured to cause a processor to perform a process. The process can be the above-described method in any of its varying embodiments. 
     An additional embodiment of the present invention can be an apparatus including a receiver configured to receive measurements regarding interference noise levels in a plurality of cells. The apparatus also includes a processor configured to define a maximum interference noise level, to classify the cells, and to calculate transmission power changes depending on the classification of the cells. The apparatus further includes a transmitter configured to forward commands to each class of the cells to implement the transmission power changes. 
     The receiver can be further configured to monitor the interference noise levels in the cells. The processor can be configured to exclude certain cells having interference noise level that exceed the maximum. The processor can be configured to change only a portion of the transmission bandwidth. 
     One having ordinary skill in the art will readily understand that the invention as discussed above may be practiced with steps in a different order, and/or with hardware elements in configurations that differ from those discussed above. Therefore, although the invention has been described based upon these embodiments, it would be apparent to those of skill in the art that certain modifications, variations, and alternative constructions would be apparent, while remaining within the spirit and scope of the invention.