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WO2011072440A1 - 一种用于无线网络的切换触发方法和装置 - Google Patents

一种用于无线网络的切换触发方法和装置 Download PDF

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Publication number
WO2011072440A1
WO2011072440A1 PCT/CN2009/075601 CN2009075601W WO2011072440A1 WO 2011072440 A1 WO2011072440 A1 WO 2011072440A1 CN 2009075601 W CN2009075601 W CN 2009075601W WO 2011072440 A1 WO2011072440 A1 WO 2011072440A1
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cinr
handover
downlink
uplink
correction
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French (fr)
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陈嘉明
肖志坚
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ZTE Corp
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ZTE Corp
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/08—Reselecting an access point

Definitions

  • the present invention relates to the field of wireless communication technologies, and in particular, to a handover triggering method and apparatus for a terminal for adapting different processing capabilities of a wireless network and an uplink and downlink coverage imbalance system. Background technique
  • Wimax With the improvement of system processing power, a new generation of wireless communication systems, such as Wimax and LTE, widely use multi-antenna technology. With appropriate transmit signal form and receiver design, multi-antenna technology can not significantly increase wireless communication. At the same time as the system cost, the system capacity is increased.
  • the Wimax system is taken as an example to introduce the multi-antenna technology.
  • Wimax supports multiple multi-antenna technologies such as MIMO (Multiple Input Multiple)
  • the WiMAX 16e protocol defines three MIMO transmit matrices that use space-time coding, namely Matrix A, Matrix B, and Matrix C.
  • Matrix A uses the transmit diversity structure to obtain spatial diversity gain.
  • the spatial diversity gain means that the signal of a single antenna system may have deep fading due to the fading characteristics of the wireless channel. After using multi-antenna technology, usually the antennas are far enough apart to ensure that the signal fading of different antennas is relatively independent. Therefore, the signal-to-noise ratio fluctuation of the combined received signal will become smooth, thereby improving the received signal quality.
  • Matrix B uses a spatial multiplexing structure to obtain multiplexing gain.
  • the spatial multiplexing gain refers to the improvement of data throughput/transmission rate under the same transmission power and the same bandwidth.
  • the spatial multiplexing gain can be obtained by transmitting multiple parallel data streams on the same time-frequency resource, and these multiplexed data streams are distinguished by different antennas.
  • Matrix C uses a hybrid structure of diversity and multiplexing to obtain both multiplexing gain and diversity gain.
  • the protocol stipulates that space-time coding cannot be used.
  • the CDD technique can be used to obtain the diversity gain.
  • CDD technology improves the coverage of common channels by transmitting different delayed copies of the same data stream on different antennas to achieve multipath diversity.
  • the CDD of 2 antennas has at least 2 dB gain than the single antenna, and the CDD of 4 antennas has more than 1 dB of gain than the CDD of 2 antennas.
  • the combination of CDD and MIMO Matrix A or Matrix B for the data channel can further improve diversity performance or diversity plus multiplexing performance.
  • Beamforming is that the transmitting end weights and transmits the data first, forming a narrow transmitting beam, and aligning the energy with the target user, thereby improving the demodulation signal-to-noise ratio of the target user, which is particularly suitable for improving the throughput of the cell edge user. effective. Beamforming can obtain array gain, diversity gain and multiplexing gain. Array gain refers to the improvement of the average signal-to-noise ratio at the receiving end under the premise of the same total transmit power. By coherently combining the signals, the received signal-to-noise ratio can be improved. . Beamforming technology and MIMO technology can be used together to achieve greater gain.
  • MIMO, CDD and Beamforming are all implemented in the downlink through BS (Base Stastion). Because BS has strong processing capability, it will generally be equipped with 4T4R (4 rounds and 4 receivers), 4T8R (4 rounds and 8 receivers) and other antennas. Capability, while MS (Mobile Station) is limited by the processing capability and mobility, and generally only configures the antenna capability of 1T1R (1 send 1 receive) or 1T2R (1 send 2 receive), so the uplink multi-antenna The technology is also implemented by the BS. There are two main technologies: uplink multi-antenna receive diversity and uplink CSM (Collaborate Spatial Multiplex). Uplink multi-antenna receive diversity is the most commonly used multi-antenna technology.
  • the signals received by multiple antennas are coherently combined at the base station side to obtain the array gain.
  • the array gain refers to the receiver with the same total transmit power. The amount of improvement in the average signal to noise ratio.
  • the array gain can be obtained for various multi-antenna systems, that is, the multi-antenna technique can be used to improve the received signal-to-noise ratio.
  • the uplink coverage will improve by more than 3dB, and the 4-antenna diversity reception can further improve l-2dB.
  • Over-multiplexing to increase the capacity of the uplink.
  • the excellent multi-antenna technology will greatly improve the spectrum efficiency, reduce the cost per bit, effectively improve the user experience, improve coverage, improve the throughput of cell edge users, reduce the number of base stations, and reduce network construction and maintenance costs.
  • the coverage of the WiMAX system is usually limited by the uplink, that is, the uplink coverage is less than the downlink coverage.
  • the multi-antenna technology mainly increases the downlink gain in the BS side application, although the uplink multi-antenna receive diversity can increase the gain by more than 3 dB, and the uplink due to the MIMO and Beamforming techniques that simultaneously obtain multiple gains.
  • the gain obtained by the antenna is far less than the gain obtained by the multi-antenna in the downlink, so the multi-antenna technology exacerbates the coverage imbalance between the uplink and the downlink.
  • Figure 1 is a schematic diagram of the difference in coverage when uplink, downlink, and multi-antenna technologies are used.
  • the inner circle range 1 indicates the uplink coverage, that is, the MS is within this range, and the BS can receive the uplink signal of the MS.
  • the outer circle range 2 indicates the downlink coverage when MIMO and Beamforming are not used; the sector area range 3 refers to the downlink coverage of MS 1 when Beamforming is enabled, and the MS has a capability of 1T2R.
  • the existing Wimax switching mechanism will be adopted. Come ⁇ ⁇ big impact.
  • the existing Wimax cell handover mechanism is mainly triggered according to the value of the downlink CINR (Carrier to Interference plus Noise Ratio), because the downlink transmission power of the BS is fixed, in the case of a single antenna.
  • the value of the downlink CINR can be used to determine the distance from the BS, and the uplink transmit power is variable.
  • the BS will indicate the MS with lower CINR and the MS with lower CINR. Power, unless the MS is already full power.
  • the BS notifies the handover threshold and the relative handover threshold to the MS through the broadcast message, and the MS measures the downlink CINR, and if the handover threshold is reached, the scan is initiated, and the record is recorded.
  • the downlink CINR of the neighboring cell initiates the handover. If a BS load is severe, the BS will only initiate the handover by the MS with poor downlink CINR.
  • the use of multi-antenna technology will increase the individual difference of MS. Whether to use multi-antenna technology and which multi-antenna technology is used is related to the capability of MS, there will be multiple MS access under one BS cell.
  • the downlink CINR of the MS is related to the multi-antenna technology used by the downlink in addition to the distance of the BS.
  • the downlink CINR of the MS at the cell edge that enables MIMO and/or Beamforming is not necessarily more than that of the non-MIMO non-Beamforming.
  • the downlink CINR of the MS in the center of the cell is low.
  • the multi-antenna technology exacerbates the coverage imbalance between the uplink and the downlink.
  • the downlink CINR is still 4 ⁇ , but the uplink has dropped.
  • all MSs in a cell now use the same handover threshold.
  • the downlink CINR cannot fully represent the location of an MS in the cell. MSs with different capabilities should have different switching thresholds.
  • the object of the present invention is to provide an enhanced handover triggering method for a wireless network, which is used to solve the call drop caused by the uplink and downlink coverage imbalance in a multi-antenna system, because the same handover threshold is easily caused for all MSs.
  • Technical defects such as misjudgment.
  • the handover triggering method of the present invention mainly includes: a handover triggering method for a wireless network, the method comprising:
  • CINR downlink carrier to interference and noise ratio
  • the average difference between the CINR before and after the multi-antenna technology is enabled or changed
  • the CINR of the MS is corrected; or the downlink CINR of the MS is corrected according to a preset CINR average correction difference corresponding to each multi-antenna technology type.
  • the handover decision is performed in combination with the uplink CINR and the transmit power, and the specific steps are:
  • the MS It is determined whether the MS is in an uplink full power transmission state, and if it is in a full load transmission state, it continues to determine whether the uplink CINR of the MS reaches a handover threshold, and if the handover threshold is reached, the MS is notified to perform handover.
  • the present invention also provides a handover triggering apparatus for a wireless network, including:
  • a downlink CINR collector configured to collect downlink CINR information on the MS
  • a downlink CINR correction information base for storing a correction parameter for correcting the MS downlink CINR
  • a handover determiner configured to modify a CINR reported by the MS according to a modified parameter of the downlink CINR correction information store, and perform a handover decision according to the corrected downlink CINR value of the MS;
  • the BS signaling processing module is configured to process the interaction signaling with the MS, and notify the MS to initiate the handover procedure according to the handover decision information of the handover decider.
  • the correction parameter stored in the downlink CINR correction information base is an average difference between the CINR calculated by the downlink CINR collector and the CINR before or after the multi-antenna technology is enabled or changed; the handover decider is according to the The MS corrects the CINR of the MS by the average difference between the CINR before and after the multi-antenna technology is enabled or changed.
  • the correction parameter stored in the downlink CINR correction information base is a preset CINR average correction difference value corresponding to each multi-antenna technology type; the handover decider is corresponding to each multi-antenna technology type.
  • the CINR average ⁇ ⁇ ' ⁇ positive difference is positive for the downlink CINR of the MS.
  • the device further includes:
  • An uplink CINR/power collector configured to collect uplink CINR information and transmit power information of the MS
  • the handover determiner is further configured to determine, according to the transmit power of the MS obtained by the uplink CINR/power collector, whether the MS is in an uplink full power transmission state, and if in a full load transmission state, continue to determine an uplink of the MS. Whether the CINR reaches the handover threshold, and if the handover threshold is reached, the handover decision information is sent to the BS signaling processing module.
  • the base station corrects the downlink CINR reported by the MS according to the MS's own capabilities and channel conditions, and performs handover decision according to the modified downlink CINR, which can maximize the handover threshold adaptation and reduce the misjudgment of the MS during handover.
  • the present invention also considers the case where the uplink and downlink coverage is unbalanced, and performs handover decision on the uplink CINR of the MS when the full power is transmitted on the base station side, so that the MS does not switch because the uplink exceeds the coverage range; The invention can improve the performance and user satisfaction of a multi-antenna system.
  • FIG. 1 is a schematic diagram of differences in coverage when uplink, downlink, and multi-antenna technologies are used;
  • FIG. 2 is a schematic structural diagram of an enhanced handover triggering apparatus for a wireless network according to the present invention;
  • FIG. 3 is an enhanced type of the present invention for wireless networks. Schematic diagram of a simplified device structure for handover triggering;
  • FIG. 4 is a flow chart showing a specific implementation of maintaining and updating a CINR correction difference value of an MS in an enhanced handover trigger of a wireless network according to the present invention;
  • FIG. 5 is a flow chart showing a specific implementation of an enhanced handover triggering method for a wireless network according to the present invention
  • the base station corrects the downlink CINR of the MS according to the difference between the downlink and the CINR of the MS enabled multi-antenna technology, and performs handover decision according to the corrected CINR value; or for different
  • the antenna technology type sets different downlink CINR correction differences, and corrects the downlink CINR reported by the MS according to the multi-antenna technology type used by the MS, and performs handover decision according to the corrected CINR value; in the case where the uplink and downlink coverage is unbalanced
  • the BS also detects the uplink CINR, and notifies the MS to initiate the handover when the MS is already transmitting at full power and reaches the handover threshold.
  • FIG. 2 is a schematic structural diagram of an enhanced handover triggering apparatus for a wireless network according to the present invention.
  • the apparatus configuration is applicable to a scenario in which a downlink CINR of each MS is corrected according to an average difference between CINRs before and after multi-antenna technology.
  • the actual switching thresholds of each MS are different.
  • the device can implement the switching threshold control at the user granularity, and improves the accuracy of the downlink CINR switching threshold of each MS.
  • the apparatus includes the following parts: a downlink CINR collector 101, configured to collect downlink CINR information of >3 ⁇ 4 on the MS; and calculate a multi-antenna technology enabling or changing downlink of the MS after the multi-antenna technology of the MS is enabled or changed CINR correction difference;
  • the MS downlink CINR information base 102 is configured to save the downlink CINR correction difference of each MS. If the MS does not enable the multi-antenna technology, the corresponding correction difference is 0.
  • the uplink CINR/power collector 103 is configured to collect uplink CINR information and transmit power information of the MS.
  • the handover determiner 104 is configured to modify, according to the downlink CINR correction difference of each MS, the downlink CINR of the MS collected by the downlink CINR collector, and perform handover decision according to the modified value, if there is an imbalance between the uplink and downlink coverage, The handover decision is made in combination with the uplink CINR and the transmit power.
  • a BS signaling processing module 105 configured to process interaction signaling with the MS, according to the handover decider
  • the handover decision information informs the MS to initiate the handover procedure.
  • FIG. 4 is a flowchart of a specific embodiment of a CINR correction difference for maintaining and updating an MS based on the handover triggering apparatus shown in FIG. 2 according to the present invention. The specific steps are as follows:
  • Step 401 The MS initially accesses the network.
  • Step 402 The MS downlink CINR information base 102 creates a corresponding downlink CINR information item for the MS, and sets the CINR correction difference value to zero.
  • Step 403 The MS performs capability negotiation with the BS.
  • Step 404 Determine whether the MS needs to enable or change the multi-antenna technology, and if necessary, go to step 405; otherwise, go to step 408;
  • Step 405 The BS signaling processing module 105 notifies the MS of the downlink CINR collector 101 and the MS downlink CINR information base 102 after a certain (MIMO A/B/C, Beamforming, and MIMO+Beamforming) multi-antenna technology is enabled or changed.
  • MIMO A/B/C, Beamforming, and MIMO+Beamforming multi-antenna technology
  • Step 406 The downlink CINR collector 101 obtains an average value of the CINR difference values before and after the enable or change according to the downlink CINR value of the MS enable or change, and notifies the MS downlink CINR information base 102;
  • Step 407 The MS downlink CINR information base 102 records the multi-antenna technology type used by the MS and the updated CINRJ ⁇ positive difference value;
  • the CINR is increased by 4 dB, the CINR correction difference is 4, and then the MIMO A is cut to MIMO C, and the CINR is reduced by IdB, and the CINR correction difference is 3.
  • Step 408 If the MS is in the network, whether to enable/change the multi-antenna technology, if yes, go to step 405, otherwise go to step 409.
  • Step 409 The MS exits the network, and the process ends.
  • FIG. 5 is a flowchart of processing performed by the apparatus according to FIG. 2 for performing enhanced handover triggering according to the present invention, and the specific steps are as follows:
  • Step 501 The uplink CINR/power collector 103 checks whether the MS is already uplink full power transmission, if yes, go to step 502, otherwise go to step 504;
  • Step 502 The uplink CINR/power collector 103 reports the uplink CINR of the MS to the switch determiner 104.
  • Step 503 The handover determiner 104 determines whether the uplink CINR of the MS has reached or is less than the uplink handover threshold, if yes, go to step 507, otherwise go to step 504;
  • Step 504 The downlink CINR collector reports the received MS downlink CINR to the handover determiner 104;
  • Step 505 The handover determiner 104 corrects the downlink CINR value of the MS according to the downlink CINR correction value of the MS in the MS downlink CINR information database, and obtains the corrected downlink CINR value of the MS.
  • the method for modifying the downlink CINR value of the MS by the BS of the present invention is: after receiving the downlink CINR reported by the MS, the BS subtracts the downlink CINR correction difference of the MS from the downlink CINR value currently reported by the MS, so that the MS is corrected. Downstream CINR value;
  • Step 506 The handover determiner 104 determines whether the corrected downlink CINR value of the MS has reached or is less than the downlink handover threshold. If yes, go to step 507; otherwise, go to step 501;
  • Step 507 The handover decider 104 notifies the BS signaling processing module 105 of the MS information that needs to be switched;
  • Step 508 The BS signaling processing module 105 notifies the MS to initiate a handover procedure.
  • FIG. 3 is a simplified block diagram of an apparatus for enhanced handover triggering of a wireless network of the present invention, the apparatus structure being adapted to set a fixed CINR average difference for each type of multi-antenna technology type, and for each MS used
  • the multi-antenna technique type uses the above fixed CINR average difference to correct the downlink CINR of the MS.
  • the scheme is relative to the scheme of Figure 2, for each The accuracy of the control of the user switching threshold is not as high as that of the scheme of Fig. 2, but the implementation is simpler and more efficient.
  • the simplified enhanced switching trigger device includes:
  • the downlink CINR collector 201 is configured to collect downlink CINR information on the MS, and the multi-antenna downlink CINR switching threshold information base 202 is configured to save a preset CINR average correction difference corresponding to each multi-antenna technology type. If the MS does not enable multiple antennas, the value is
  • the uplink CINR/power collector 203 is configured to collect uplink CINR information and transmit power information of the MS.
  • the handover determiner 204 is configured to modify, according to the CINR average correction difference corresponding to each multi-antenna technology type, the downlink CINR of the MS collected by the downlink CINR collector, and perform handover decision according to the modified value, if there is uplink and downlink coverage. In the case of balance, the handover decision is made in combination with the uplink CINR and the transmit power.
  • the BS signaling processing module 205 is configured to process the interaction signaling with the MS, and notify the MS to initiate the handover procedure according to the handover decision information of the handover determiner.
  • FIG. 6 is a flowchart of a handover triggering process of the simplified device based on the enhanced handover trigger of FIG. 3, which specifically includes the following steps:
  • Step 601 The uplink CINR/power collector 203 checks whether the MS is already uplink full power transmission, if yes, go to step 602, otherwise go to step 604.
  • Step 602 The uplink CINR/power collector 203 reports the uplink CINR of the MS to the handover decider 204.
  • Step 603 The handover determiner 204 determines whether the uplink CINR of the MS has reached or is less than the uplink handover threshold. If yes, go to step 607. Otherwise, go to step 604.
  • Step 604 The downlink CINR collector reports the received MS downlink CINR to the handover decider 204.
  • Step 605 The handover determiner 204 switches the threshold information base 202 according to the multi-antenna downlink CINR.
  • the CINR average correction difference corresponding to the multi-antenna technology type used by the MS corrects the downlink CINR value of the MS.
  • Step 606 Whether the downlink CINR correction value of the MS has reached or is less than the downlink handover threshold, if yes, go to step 607, otherwise go to step 601.
  • Step 607 The handover decider 204 notifies the BS signaling processing module 205 of the MS information that needs to be handed over.
  • Step 608 The BS signaling processing module 205 notifies the MS to initiate a handover procedure.

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Abstract

本发明提供了一种用于无线网络的切换触发方法和装置，用于解决在多天线系统中由于上下行覆盖不平衡而引起掉话、针对所有MS采用相同切换门限容易引起误判等技术缺陷。本发明中，基站对MS上报的下行CINR按MS自身能力和信道情况进行修正，并根据修正后的下行CINR进行切换判决，能够最大限度做到切换门限自适应，减少MS在切换时的误判断；同时本发明还考虑了上下行覆盖不平衡的情况，在基站侧对MS的满功率发射时的上行CINR进行切换判决，使MS不会因为上行超出覆盖范围而没切换造成掉话；基于上述特点，本发明可提升多天线系统的性能和用户满意度。

Description

一种用于无线网络的切换触发方法和装置 技术领域
本发明涉及无线通信技术领域， 尤其涉及一种用于无线网络的适应不 同处理能力的终端和上下行覆盖不平衡系统的切换触发方法和装置。 背景技术
随着系统处理能力的提高， 新一代的无线通信系统， 如 Wimax和 LTE 等， 都广泛地使用多天线技术， 通过适当的发射信号形式和接收机设计， 多天线技术可以在不显著增加无线通信系统成本的同时， 提高系统容量， 下面以 Wimax系统为例介绍多天线技术。
Wimax 支持多种多天线技术， 例如 MIMO ( Multiple Input Multiple
Output, 多输入多输出 )技术、 CDD ( Cyclic Delay Diversity, 循环时延分 集）技术、 Beamforming (波束赋形 )技术， 通过这些多天线技术可大幅提 升系统容量。
WiMAX 16e协议定义了三种釆用空时编码的 MIMO发射矩阵，分别为 Matrix A、 Matrix B和 Matrix C。 Matrix A釆用发射分集结构， 可获得空间 分集增益， 空间分集增益是指由于无线信道的衰落特性， 单天线系统的信 号可能存在深衰落。 釆用多天线技术后， 通常各天线间隔足够远， 可保证 不同天线的信号衰落相对独立。 因此， 合并后的接收信号的信噪比波动将 变得平稳， 从而改善了接收信号质量。 Matrix B釆用空间复用结构， 可获得 复用增益， 空间复用增益是指在相同发射功率和相同带宽的前提下， 对数 据吞吐量 /传输速率的改善。 空间复用增益可通过在相同的时频资源上传送 多个并行的数据流获得， 而这些复用的数据流通过不同的天线来区分。 Matrix C釆用分集与复用的混合结构， 可以同时获得复用增益和分集增益。 对下行公共信道， 协议规定不能釆用空时编码， 此时可釆用 CDD技术 获得分集增益。 CDD技术是通过在不同的天线上发射同一数据流的不同延 迟副本， 以获得多径分集效果， 从而提升公共信道的覆盖。 按仿真结果， 2 天线的 CDD比单天线至少有 2个 dB的增益， 4天线的 CDD又比 2天线的 CDD多 1个 dB以上的增益。 另夕卜， 对数据信道还可以釆用 CDD与 MIMO 的 Matrix A或 Matrix B的结合， 进一步提高分集性能或分集加复用性能。
下行波束赋形 （Beamforming )是发射端对数据先加权再发送， 形成窄 的发射波束， 将能量对准目标用户， 从而提高目标用户的解调信噪比， 这 对改善小区边缘用户吞吐率特别有效。 Beamforming可以获得阵列增益、分 集增益和复用增益， 阵列增益是指在发射总功率相同的前提下， 对接收端 平均信噪比的改善量， 通过对信号的相干合并， 可提高接收信噪比。 Beamforming技术和 MIMO技术可以一起来使用， 以获得更大的增益。
MIMO, CDD和 Beamforming—般都是通过 BS ( Base Stastion, 基站） 在下行实现， 因为 BS有较强的处理能力， 一般都会配置 4T4R ( 4发 4收）， 4T8R ( 4发 8收）等天线能力， 而 MS ( Mobile Station, 移动台 ) 由于受处 理能力和移动性等限制， 一般只会配置 1T1R ( 1发 1收）或 1T2R ( 1发 2 收）的天线能力， 所以上行的多天线技术也是由 BS来实现的， 主要有两种 技术： 上行多天线接收分集和上行 CSM ( Collaborate Spatial Multiplex, 合 作空间复用）。 上行多天线接收分集， 是最常用的多天线技术， 在基站侧对 多根天线接收到的信号进行相干合并， 从而获得阵列增益， 阵列增益是指 在发射总功率相同的前提下， 对接收端平均信噪比的改善量。 通过对信号 的相干合并， 各种多天线系统都可以获得阵列增益， 也就是说， 釆用多天 线技术后， 可提高接收信噪比。 与单天线接收相比， 釆用 2天线分集接收， 上行覆盖将改善 3dB以上，而釆用 4天线分集接收，还可进一步改善 l-2dB。 过复用来提升上行的容量。 选择协作终端时， 要保证用户之间的正交性， 对调度算法有较高的要求。
优良的多天线技术将大幅提升频谱效率， 降低每比特成本， 有效提升 用户体验， 还可以提高覆盖， 改善小区边缘用户的吞吐率， 减少基站数目， 降低建网及维护成本。
由于受 MS的处理能力和发射功率的限制， WiMAX系统的覆盖通常是 上行受限， 即上行的覆盖少于下行的覆盖。 由上面的介绍可知， 多天线技 术主要是在 BS侧应用增加了下行增益，尽管上行多天线接收分集可以增加 3dB以上的增益， 而相对于同时获得多种增益的 MIMO和 Beamforming技 术， 上行因多天线获得的增益远远少于下行因多天线获得的增益， 所以多 天线技术是加剧了上下行的覆盖不平衡。 图 1 为上行、 下行及使用多天线 技术时覆盖范围的差异性示意图， 如图所示， 内圈范围 1 表示上行覆盖范 围， 即 MS在此范围内， BS都可以收到 MS的上行信号； 外圈范围 2表示 没使用 MIMO和 Beamforming时的下行覆盖范围； 扇形区域范围 3指使能 Beamforming时， 对 MS 1的下行覆盖范围， MS的能力为 1T2R。
多天线技术广泛应用后， 当一个小区中拥有多种处理能力的 MS 时， 如只支持单天线的 MS、 支持 MIMO的 MS、 支持 MIMO和 Beamforming 的 MS等， 对现有的 Wimax切换机制会带来^ ί艮大的冲击。
现有的 Wimax 小区切换机制主要是根据下行 CINR ( Carrier to Interference plus Noise Ratio , 载波与干扰和噪声比 )的值来触发的， 原因是 BS的下行发射功率是固定的， 在单天线的情况下， 可以通过下行 CINR的 值来判断与 BS的距离的远近， 而上行的发射功率是可变的， 为了减少上行 干扰， BS会指示 CINR较高的 MS降发射功率， CINR较低的 MS升发射功 率， 除非 MS已经是满功率发射。 BS通过广播消息通知切换门限和相对切 换门限给 MS, MS测量下行 CINR, 假如达到切换门限就发起扫描， 记录 相邻小区的下行 CINR, 假如本小区的 CINR与邻区的 CINR相比小于相对 切换门限就发起切换； 如果一个 BS负载比较严重， BS也只会挑下行 CINR 较差的 MS发起切换。
而多天线技术的使用会加大 MS 的个体差异性， 是否使用多天线技术 和使用哪种多天线技术与 MS的能力有关，一个 BS小区下会有多种 MS接 入。 MS的下行 CINR除了与 BS的距离相关外还与下行所使用的多天线技 术有关，一个使能 MIMO和 /或 Beamforming的处于小区边缘的 MS的下行 CINR不一定会比非 MIMO非 Beamforming使能的在小区中央的 MS的下 行 CINR低。 而且多天线技术加剧了上下行的覆盖不平衡，也就是说由于使 用了多天线技术， MS在小区边缘的时候， 下行 CINR还 4艮高， 但上行已经 掉话。 另外， 现在是一个小区内所有的 MS都釆用相同的切换门限， 而在 多天线设计下， 下行 CINR不能完全代表一个 MS在小区的位置。不同能力 的 MS应该有不同的切换门限。 发明内容
本发明的目的在于， 提出一种用于无线网络的增强型切换触发方法， 用于解决在多天线系统中由于上下行覆盖不平衡而引起掉话， 由于针对所 有 MS釆用相同切换门限容易引起误判等技术缺陷 。
本发明釆用以下技术方案， 本发明所述的切换触发方法主要包括： 一种用于无线网络的切换触发方法， 该方法包括：
对移动台 （MS )的下行载波与干扰和噪声比 (CINR)进行修正， 并根据 所述 MS修正后的下行 CINR进行切换判决，若所述 MS修正后的下行 CINR 达到切换门限， 则通知所述 MS执行切换。
进一步地， 所述修正具体为：
根据所述 MS在多天线技术使能或改变前后 CINR的平均差值对所述 MS的 CINR进行修正；或根据预先设定的每种多天线技术类型对应的 CINR 平均修正差值对所述 MS的下行 CINR进行修正。
进一步地，在下行覆盖不平衡的情况下结合上行的 CINR和发射功率执 行所述切换判决， 具体步骤为：
判断所述 MS是否处于上行满功率发送状态， 若处于满负荷发送状态， 则继续判断所述 MS的上行 CINR是否达到切换门限，若达到切换门限则通 知所述 MS执行切换。
基于上述方法， 本发明还提出一种用于无线网络的切换触发装置， 包 括：
下行 CINR收集器， 用于收集 MS上^艮的下行 CINR信息；
下行 CINR修正信息库，用于保存用于对 MS下行 CINR进行修正的修 正参数；
切换判决器， 用于根据下行 CINR修正信息库存储的修正参数对 MS 上报的 CINR进行修正，并根据所述 MS修正后的下行 CINR值进行切换判 决；
BS信令处理模块， 用于处理与 MS的交互信令， 根据所述切换判决器 的切换判决信息通知 MS启动切换流程。
进一步地， 所述下行 CINR修正信息库所存储的修正参数为所述下行 CINR收集器计算的所述 MS在多天线技术使能或改变前后 CINR的平均差 值；所述切换判决器根据所述 MS在多天线技术使能或改变前后 CINR的平 均差值对 MS的 CINR进行爹正。
进一步地，所述下行 CINR修正信息库所存储的修正参数为预先设定的 每种多天线技术类型对应的 CINR平均修正差值；所述切换判决器根据所述 每种多天线技术类型对应的 CINR平均^ ί'爹正差值对 MS的下行 CINR进行^ i 正。 进一步地， 所述装置还包括：
上行 CINR/功率收集器，用于收集 MS的上行 CINR信息和发射功率信 息；
所述切换判决器还用于根据所述上行 CINR/功率收集器获得的 MS 的 发射功率判断所述 MS是否处于上行满功率发送状态， 若处于满负荷发送 状态，则继续判断所述 MS的上行 CINR是否达到切换门限，若达到切换门 限则向所述 BS信令处理模块发送切换判决信息。
本发明中，基站对 MS上报的下行 CINR按 MS自身能力和信道情况进 行修正，并根据修正后的下行 CINR进行切换判决， 能够最大限度做到切换 门限自适应， 减少 MS在切换时的误判断； 同时本发明还考虑了上下行覆 盖不平衡的情况，在基站侧对 MS的满功率发射时的上行 CINR进行切换判 决， 使 MS 不会因为上行超出覆盖范围而没切换造成掉话； 通过本发明可 提升多天线系统的性能和用户满意度。 附图说明
图 1是上行、 下行及使用多天线技术时覆盖范围的差异性示意图； 图 2是本发明用于无线网络的增强型切换触发装置的结构示意图； 图 3是本发明用于无线网络的增强型切换触发的简化装置结构示意图； 图 4是本发明用于无线网络的增强型切换触发中维护和更新 MS 的 CINR修正差值的具体实施的流程图；
图 5是本发明用于无线网络的增强型切换触发方法的具体实施的流程 图；
图 6是本发明用于无线网络的增强型切换触发简化方法的具体实施的 流程图。 具体实施方式 本发明基本思想是：基站根据 MS使能多天线技术前后下行 CINR的差 值对 MS上^艮的下行 CINR进行修正，并按修正后的 CINR值进行切换判决； 或针对不同的多天线技术类型设置不同的下行 CINR修正差值， 根据 MS 所使用的多天线技术类型对 MS上报的下行 CINR进行修正，并按修正后的 CINR值进行切换判决； 在上下行覆盖不平衡的情况下， BS还同时检测上 行 CINR, 在 MS已是满功率发射且达到切换门限时， 通知 MS发起切换。
以下结合实施例及附图对本发明的技术方案进行详细说明。
图 2是本发明用于无线网络的增强型切换触发装置的结构示意图， 该 装置结构适用于对每个 MS的下行 CINR根据其釆用多天线技术前后 CINR 的平均差值进行修正的场景。 使用该技术方案时， 每一个 MS 所对应的实 际的切换门限都是不同的， 该装置可实现以用户粒度进行切换门限的控制， 提升了每个 MS的下行 CINR切换门限的精确度。 该装置包括以下部分： 下行 CINR收集器 101 , 用于收集 MS上>¾的下行 CINR信息； 并在 MS的多天线技术使能或改变后计算该 MS的多天线技术使能或改变前后的 下行 CINR修正差值；
MS下行 CINR信息库 102,用于保存每个 MS的下行 CINR修正差值， 若 MS没有使能多天线技术， 则对应的修正差值为 0。
上行 CINR/功率收集器 103 , 用于收集 MS的上行 CINR信息和发射功 率信息。
切换判决器 104,用于根据每个 MS的下行 CINR修正差值对下行 CINR 收集器收集上来的 MS的下行 CINR作修正，根据此修正值做切换判决，如 果存在上下行覆盖不平衡的情况， 结合上行的 CINR和发射功率做切换判 决。
BS信令处理模块 105, 用于处理与 MS的交互信令， 根据切换判决器 的切换判决信息通知 MS启动切换流程。
下面详细介绍本发明用于无线网络的增强型切换判决的具体实施步 骤。
图 4为本发明基于图 2所示的切换触发装置维护和更新 MS的 CINR修 正差值的具体实施例的流程图， 具体步骤如下：
步骤 401 : MS初始接入网络；
步骤 402: MS下行 CINR信息库 102为该 MS创建相应的下行 CINR 信息项， 并将 CINR修正差值置为 0。
步骤 403: 该 MS与 BS进行能力协商；
步骤 404: 判断该 MS是否需要使能或改变多天线技术， 若需要则转至 步骤 405; 否则转至步骤 408; 。
步骤 405: BS信令处理模块 105在某种（MIMO A/B/C、 Beamforming 及 MIMO+Beamforming ) 多天线技术使能或改变后通知下行 CINR收集器 101及 MS下行 CINR信息库 102所述 MS的使能的多天线技术类型；
步骤 406: 下行 CINR收集器 101根据该 MS使能或改变前后各 10次 的下行 CINR值求出使能或改变前后 CINR差值的平均值， 并将此值通知 MS下行 CINR信息库 102;
步骤 407: MS下行 CINR信息库 102记录该 MS使用的多天线技术类 型和更新 CINRJ爹正差值；
例如 MS从单天线切换到 MIMO A后 , CINR增加了 4dB, 则 CINR修 正差值为 4, 再从 MIMO A切到 MIMO C, CINR减少了 IdB, 则 CINR修 正差值为 3。
步骤 408: 该 MS在网时， 是否使能 /改变多天线技术， 是则转至步骤 405, 否则转至步骤 409。
步骤 409: MS退网， 此流程结束。 图 5为本发明基于图 2所述装置进行增强型切换触发的处理流程， 具 体步骤如下：
步骤 501 : 上行 CINR/功率收集器 103检查 MS是否已经是上行满功率 发送， 是则转至步骤 502, 否则转至步骤 504;
步骤 502: 上行 CINR/功率收集器 103将此 MS的上行 CINR上报给切 换判决器 104;
步骤 503: 切换判决器 104判断此 MS的上行 CINR是否已经达到或小 于上行切换门限， 是则转至步骤 507, 否则转至步骤 504;
步骤 504: 下行 CINR收集器将收到的 MS下行 CINR上报给切换判决 器 104;
步骤 505: 切换判决器 104根据 MS下行 CINR信息库中此 MS的下行 CINR修正差值对 MS的下行 CINR值进行修正， 得到该 MS修正后的下行 CINR值；
本发明 BS对 MS的下行 CINR值进行修正的方法为： BS收到 MS上 报的下行 CINR后， 使用 MS 当前上报的下行 CINR值减去该 MS的下行 CINR修正差值， 从而得到该 MS修正后的下行 CINR值；
步骤 506: 切换判决器 104判断该 MS修正后的下行 CINR值是否已经 达到或小于下行切换门限， 是则转至步骤 507, 否则转至步骤 501 ;
步骤 507: 切换判决器 104将需要切换的 MS信息通知 BS信令处理模 块 105;
步骤 508: BS信令处理模块 105通知 MS发起切换流程。
图 3是本发明用于无线网络的增强型切换触发的简化装置结构图， 该 装置结构适用于对每一类多天线技术类型设置一固定的 CINR平均差值，并 针对每一 MS所使用的多天线技术类型使用上述固定的 CINR平均差值对该 MS的下行 CINR进行修正的场景。 该方案相对于图 2的方案来说， 对每个 用户切换门限的控制的精确度没有的图 2 的方案高， 但实现较为简单， 效 率较高。 该简化的增强型切换触发装置包括：
下行 CINR收集器 201 , 用于收集 MS上 4艮的下行 CINR信息； 多天线下行 CINR切换门限信息库 202,用于保存预先设定的每种多天 线技术类型对应的 CINR平均修正差值，若 MS没有使能多天线， 则该值为
0。
上行 CINR/功率收集器 203 , 用于收集 MS的上行 CINR信息和发射功 率信息。
切换判决器 204,用于根据每种多天线技术类型对应的 CINR平均修正 差值对下行 CINR收集器收集上来的 MS的下行 CINR作修正，根据此修正 值做切换判决，如果存在上下行覆盖不平衡的情况，结合上行的 CINR和发 射功率做切换判决。
BS信令处理模块 205, 用于处理与 MS的交互信令， 根据切换判决器 的切换判决信息做通知 MS启动切换流程。
图 6为本发明基于图 3的增强型切换触发的简化装置的切换触发处理 流程， 具体包括如下步骤：
步骤 601 : 上行 CINR/功率收集器 203检查 MS是否已经是上行满功率 发送， 是则转至步骤 602, 否则转至步骤 604。
步骤 602: 上行 CINR/功率收集器 203将此 MS的上行 CINR上报给切 换判决器 204。
步骤 603: 切换判决器 204判断此 MS的上行 CINR是否已经达到或小 于上行切换门限， 是则转至步骤 607, 否则转至步骤 604。
步骤 604: 下行 CINR收集器将收到的 MS下行 CINR上报给切换判决 器 204。
步骤 605: 切换判决器 204根据多天线下行 CINR切换门限信息库 202 中此 MS所使用的多天线技术类型对应的 CINR平均修正差值对 MS的下行 CINR值进行修正。
步骤 606: MS的下行 CINR修正值是否已经达到或小于下行切换门限， 是则转至步骤 607, 否则转至步骤 601。
步骤 607: 切换判决器 204将需要切换的 MS信息通知 BS信令处理模 块 205。
步骤 608: BS信令处理模块 205通知 MS发起切换流程。
以上所述， 仅为本发明的较佳实施例而已， 并非用于限定本发明保护 范围。

Claims

权利要求书
1、 一种用于无线网络的切换触发方法， 其特征在于， 该方法包括： 对移动台 （MS )的下行载波与干扰和噪声比 (CINR)进行修正， 并根据 所述 MS修正后的下行 CINR进行切换判决，若所述 MS修正后的下行 CINR 达到切换门限， 则通知所述 MS执行切换。
2、 根据权利要求 1所述的方法， 其特征在于， 所述修正具体为： 根据所述 MS在多天线技术使能或改变前后 CINR的平均差值对所述 MS的 CINR进行爹正。
3、 根据权利要求 1所述的方法， 其特征在于， 所述修正具体为： 根据预先设定的每种多天线技术类型对应的 CINR平均修正差值对所 述 MS的下行 CINR进行修正。
4、 根据权利要求 1或 2所述的方法， 其特征在于， 在下行覆盖不平衡 的情况下结合上行的 CINR和发射功率执行所述切换判决， 具体步骤为： 判断所述 MS是否处于上行满功率发送状态， 若处于满负荷发送状态， 则继续判断所述 MS的上行 CINR是否达到切换门限，若达到切换门限则通 知所述 MS执行切换。
5、 一种用于无线网络的切换触发装置， 其特征在于， 包括：
下行 CINR收集器， 用于收集 MS上报的下行 CINR信息；
下行 CINR修正信息库，用于保存用于对 MS下行 CINR进行修正的修 正参数；
切换判决器， 用于根据下行 CINR修正信息库存储的修正参数对 MS 上报的 CINR进行修正，并根据所述 MS修正后的下行 CINR值进行切换判 决；
BS信令处理模块， 用于处理与 MS的交互信令， 根据所述切换判决器 的切换判决信息通知 MS启动切换流程。
6、 根据权利要求 5所述的装置， 其特征在于， 所述下行 CINR修正信 息库所存储的修正参数为所述下行 CINR收集器计算的所述 MS在多天线技 术使能或改变前后 CINR的平均差值；所述切换判决器根据所述 MS在多天 线技术使能或改变前后 CINR的平均差值对 MS的 CINR进行修正。
7、 根据权利要求 5所述的装置， 其特征在于， 所述下行 CINR修正信 息库所存储的修正参数为预先设定的每种多天线技术类型对应的 CINR平 均修正差值； 所述切换判决器根据所述每种多天线技术类型对应的 CINR 平均修正差值对 MS的下行 CINR进行修正。
8、 根据权利要求 6或 7所述的装置， 其特征在于， 所述装置还包括： 上行 CINR/功率收集器，用于收集 MS的上行 CINR信息和发射功率信 息；
所述切换判决器还用于根据所述上行 CINR/功率收集器获得的 MS 的 发射功率判断所述 MS是否处于上行满功率发送状态， 若处于满负荷发送 状态，则继续判断所述 MS的上行 CINR是否达到切换门限，若达到切换门 限则向所述 BS信令处理模块发送切换判决信息。
PCT/CN2009/075601 2009-12-15 2009-12-15 一种用于无线网络的切换触发方法和装置 Ceased WO2011072440A1 (zh)

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