【正文】 encies are TCH frequencies. TCH采用33復(fù)用，37/3=12（余1）所以一個基站三個小區(qū)的TCH可以配置為4，4，4。3 X 3 reuse mode is used for TCH, and 37/3 = 37 (with the remainder 1), so TCHs of three cells in a base station can be configured as 4, 4, 4. 由上面可知最大站型為S555Thus, the maximum site is S555. 7. 如果在GSM規(guī)劃中有10M帶寬，請分別采用下面兩種方式進行頻率規(guī)劃：10M bandwidth is specified in the GSM planning. Please plan the frequencies in the following two ways: 1) 不采用跳頻的情況下，如果全部使用 43的復(fù)用方式，請問可以配置的最大站型是多少：Suppose frequency hopping is not used, and 4 X 3 reuse mode is used for all frequencies. Please calculate the maximum site that can be configured. 2) 采用13復(fù)用跳頻，跳頻負荷是50％。那么，通常情況下，請問可以配置的最大站型是多少？1 X 3 reuse mode is used for frequency hopping, and the load of frequency hopping is 50%. Please calculate the maximum site that can be configured generally. 通過上面兩種規(guī)劃，請談?wù)勀銓Ω邢耄縋lease discuss your opinion about the two planning methods. 答：10M帶寬共有10M/200K＝50個頻點可用，Answer: 10M bandwidth provides 10M/200K=50 frequencies. 1) 由于BCCH采用43復(fù)用，則4個基站12個小區(qū)所用的BCCH頻點數(shù)為：12個，剩余的50－12＝38個頻點，一個為隔離頻點，37個是TCH頻點。Because 4 X 3 reuse mode is used for BCCH, then 12 cells in four base stations use 12 BCCH frequencies, and there are 50 – 12 = 38 frequencies left, among which one is the isolation frequency, and 37 are TCH frequencies. TCH也采用43復(fù)用，則：37/4=9，總共剩一個頻點。所以一個基站的TCH可以配置為3，3，3。4 X 3 reuse mode is also used for TCH, and 37/4 = 9, with one frequency left. So TCHs of one base station can be configured as 3, 3, 3. 所以基站的最大站型為：S444（如果回答成：S544也可以，因為剩余的一個頻點可以配置到四個基站中的任何一個，配置就成為了：S544）Therefore, the maximum site of base station is S444 (S544 is also right, because the remaining one frequency can be configured to any of the four base stations to form S544)2) 由于BCCH不參加跳頻，而采用43復(fù)用，則4個基站12個小區(qū)所用的BCCH頻點數(shù)為：12個，剩余的50－12＝38個頻點，一個為隔離頻點，37個是TCH頻點。Because BCCH does not participate in the frequency hopping and 4 X 3 reuse mode is used for BCCH, then 12 cells in four base stations use 12 BCCH frequencies, and there are 50 – 12 = 38 frequencies left, among which one is the isolation frequency, and 37 are TCH frequencies. （37－1）/3=12，根據(jù)跳頻負荷是50％，所以，每個小區(qū)可使用的邏輯頻點為6個。(371)/3=12, and the load of frequency hopping is 50%. Therefore, each cell can use 6 logical frequencies. 由上面可知最大站型為S777。Thus, the maximum site is S777. 對于上述兩個規(guī)劃方案的比較，參考答案如下：The following answer can be obtained from parison of the above two planning schemes. 采用了跳頻技術(shù)，可以看到系統(tǒng)容量有了較大幅度的提高。跳頻技術(shù)主要帶來的好處就是所謂頻率分集(Frequency Diversity)和干擾分集(Interference Diversity)的效果。第一是頻率分集，跳頻可以保證各個突發(fā)在不同的頻率上發(fā)射，這樣就可以對抗由于瑞利衰落等引起的影響，因為這些影響是因頻率而異的。第二是干擾分集，在高業(yè)務(wù)地區(qū)，由頻率復(fù)用帶來的干擾顯得較為突出。引入跳頻后，我們可以對使用相同頻率組的遠地蜂窩小區(qū)配置不同的跳頻序列，這樣就可以分散使用相同頻率集的信道之間的干擾，從中得到收益The system capacity increases substantially when the frequency hopping technology is used. This technology brings the benefit of effect of frequency diversity and interference diversity. One is the frequency diversity. Frequency hopping can ensure various bursts are transmitted on different frequencies. This will prevent the influences from Raileigh Fading because such influences vary with the frequencies. The second is the interference diversity. Frequency reuse will result in serious interference in the areas with high traffic. After the frequency hopping technology is employed, we can configure different frequency hopping sequences for the remote cells with the same frequency group. This way, the interferences between channels using the same frequency set can be distributed. 8. 一個DCS1800基站，無塔放安裝。假設(shè)其上、下行路徑損耗相同，基站接收靈敏度為109dBm，手機靈敏度為102dBm，采用13dBd的定向天線，合路器損耗為8dB，7/8饋線長度為50米（），其他接頭損耗忽略不計。 在上述前提下，手機滿功率發(fā)射時，根據(jù)上下行平衡原則，理論上基站輸出功率應(yīng)為多少dBmThe DCS1800 base station has no tower amplifier installed. Suppose its uplink and downlink losses are the same, the antenna diversity gain is , the receiver sensitivity of base station is 109dBm, the sensitivity of cell phone is 102dBm, the 13dBd directional antenna is used, the loss of biner is 8dB, the 7/8 feeder is 50m long (wit the loss as ), and the losses of other connectors are ignored. Please calculate the output power (dBm) of the base station in theory according to the uplink/downlink balance principle when the mobile phone transmits at full power. 答：先計算上行路徑允許的最大傳播損耗，設(shè)為Lu，題中說明是1800手機，因此，根據(jù)協(xié)議，手機的最大物理發(fā)射功率為1W，即30dBm，按照上行信號傳輸路徑，有下式：Answer: First calculate the allowed maximum propagation loss Lu of the uplink. Because the 1800 mobile phone is used, its maximum physical transmitter power is 1W, namely 30dBm according to the protocol. According to the transmission path for the uplink signal, 30Lu++13+設(shè)基站輸出功率應(yīng)為Tx，下行路徑損耗為Ld，對于下行有：Suppose the output power of base station is Tx, the path loss of the downlink is Ld, then for the downlink: +13+=102在上下行平衡的情況下，Lu=Ld，When the uplink and downlink are balanced, Lu=Ld, 解出：Tx=The result is: Tx=1 SCCP有幾類業(yè)務(wù)？在GSM系統(tǒng)中，使用了哪幾類業(yè)務(wù)？Which services does SCCP provide? Which of them are used in the GSM system? 答案：SCCP共有四類業(yè)務(wù)。GSM中，A接口用到了大量面向連接和部分無連接的業(yè)務(wù)；NSS系統(tǒng)只用到了無連接業(yè)務(wù)。Answer: SCCP has four types of services. In GSM, the A interface uses lost of connectionoriented services and some of the connectionless services. The NSS system only uses the connectionless services. 2. BSSMAP與DTAP在消息結(jié)構(gòu)上有什么不同？What is the difference between BSSMAP and DTAP in the message structure? 答案：鑒別參數(shù)不同，DTAP是01，BSSMAP為00； DTAP有數(shù)據(jù)鏈路識別（DLCI），而BSSMAP則沒有Answer: They have different values of authentication parameter, which is 01 for DTAP, and 00 for SSMAP. DTAP has Data Link Connection Identifier (DLCI), but BSSMAP hasn’t. 3. 在呼叫流程中，請解釋早指配、晚指配、及早指配的區(qū)別。我們一般使用哪一種方式？簡要分析優(yōu)缺點。Please explain the differences among early assignment, late assignment and very early assignment in the call flow. 答案：Answer:及早指配流程在立即指配階段就指配TCH信道，首先將TCH用作信令信道，后使用模式修改流程將其修改為傳話音的模式。早指配是先在立即指配時指配SDCCH信道，后在回鈴音之前指配TCH。晚指配則在回鈴音之后指配TCH。In the very early assignment flow, the TCH is assigned at the immediate assignment phase. First TCH is used as a signaling channel, and then it is changed to voice transmission mode using the mode change flow. In early assignment, S