在這篇論文中，我們探討在第三代無線通訊寬頻分碼多工存取系統中的即時干擾訊號估測技術。寬頻分碼多工存取系統提供了許多不同的服務，而這些服務分別需要不同的傳輸速率，對應到不同的通道品質。我們可以很明顯的看到，即時通道品質估測技術是能否成功及有效率的在寬頻分碼多工存取系統中提供各種無線多媒體服務的關鍵所在。
最基本的干擾訊號量測的概念源自於「訊號干擾比」估測的問題。在此之前，已有一些在分時多工存取及分碼多工存取系統中估測訊號干擾比的方法被提出來。在這篇論文中，我們將其中一種低複雜度，原被提出來在分時多工存取系統中估測訊號干擾比的方法，稱做「干擾投射」，推廣至分碼多工存取系統，並且考慮頻率選擇性衰減通道之環境。然而，這個方法有一項要求，就是不同的使用者必須使用不同的「訓練資料」。在分碼多工存取系統中，並沒有很明顯的所謂的訓練資料，唯一可能的解決方法是利用分碼多工存取系統中本來已有的「引導訊號」來取代訓練資料。但是在寬頻分碼多工存取系統中，不同引導訊號的組合有限，因此這個方法在很多使用者的情況之下無法運作。此外，利用引導訊號來估測干擾訊號並無法達到「即時估測」的要求，因為這個方法是對記號層次的訊號作處理。

為了使干擾訊號的估測更加實際可行，並且達到在系統運作服務當中可即時估測的要求，我們提出了一個創新的概念，利用分碼多工存取系統中的展頻碼「基片訊號」來估測干擾訊號。這個方法的關鍵在於利用各個不同使用者的不同的展頻碼基片來取代干擾投射方法中的訓練資料。這個方法有兩個主要的優點：第一，所有使用者的展頻碼皆不同，且在接收端是已知的；第二，因為我們現在是在處理基片層次的訊號，所以估測值可以在數個基片訊號時間之內收斂，而達到即時估測的目標。

我們在考慮多重路徑頻率選擇性衰減通道的寬頻分碼多工存取系統中評估這個碎片層次干擾訊號量測的方法。我們將這個方法應用在上行鏈路和下行鏈路的情況，並且考慮不同展頻碼和擾亂碼的組合，來觀察它的表現。我們將會在接下來的論文中看到，我們所提出的方法可以在0.1千分之一秒之內，得到估測百分誤差在5％之內的干擾訊號估測值。因此，利用這個方法，我們可以輕易的達到寬頻分碼多工存取系統中每0.667秒估測一次訊號干擾比的要求。

除此之外，我們還可以將這個方法應用在傳輸速率調變、傳送能量控制等無線資源管理的問題上，藉由比較快速且準確的通道品質資訊，達到可以讓這些演算法在一個接一個時槽之間不斷更新結果的目的。因此，我們可以預期，這個基片層次干擾訊號估測的技術，在未來完成高速無線多媒體通訊的過程中，將可能扮演一個相當關鍵的角色。

In this thesis, we investigate real-time interference measurement techniques for the 3rd generation wireless communication Wideband CDMA networks. The WCDMA system has versatile services with different data rates corresponding to different channel qualities. Obviously, a real-time channel quality measurement technique is the key to the success of effectively providing the wireless multimedia services in the WCDMA system.
The basic idea of interference measurement comes from solving the signal-to-interference ratio (SIR) estimation problem. Several SIR estimation methods have been proposed for TDMA and CDMA cellular systems. We extend a low complexity method called interference projection, which was originally proposed for TDMA system, to CDMA system under a frequency-selective fading channel environment. However, the method requires different training sequences for different users. Since there is no obvious so-called training sequence in CDMA system, a possible solution is to use different patterns of pilot bits to replace the training sequences. Nevertheless, there are only very few pilot patterns in the WCDMA system, this solution may not be feasible to support a large number of users. Besides, using pilot bits for measuring the interference is difficult to achieve the goal of real-time measurement because signals are processed at the symbol level.

To make it more practically and meet the demand of in-service real-time measuring, we proposed an innovative chip-based interference measurement technique. The key concept of this proposed method is to use the different subscribers’different spreading codes to replace the training sequences in the interference projection method. There are two major advantages for this solution. First, all the users’spreading codes are different and known only to the receiver for the user of interest. Second, since the signals are processed at chip-level, it is possible for the measurement to converge within a certain number of chip durations thereby achieving the goal of real-time measurement.

We evaluate the chip-based interference measurement technique in the frequency-selective fading channel for the Wideband CDMA system. For both uplink and downlink cases, we apply our algorithms under different combination of spreading and scrambling codes. It will be demonstrated that the proposed methods can obtain the interference measurement within 0.1 msec with an average percentage error less than 5%. Therefore, we can easily achieve the requirement of estimating the SIR for every 0.667 msec time slot specified in the Wideband CDMA system.

As a result, by employing the proposed chip-based interference measurement, many radio resource management algorithms, such as rate adaptation, power control, handover, and so on, can be enhanced to the slot-by-slot based adaptation algorithms to take advantage of better knowledge of channel quality. Hence, it can be expected that the proposed chip-based interference measurement technique will be possible to play a key role to fulfill the dream of high speed wireless multimedia communications in the future.

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