From c1db4510292b388c228d8d8dab18c6d09cc869ba Mon Sep 17 00:00:00 2001 From: Philipp Le Date: Tue, 30 Jun 2020 17:06:54 +0200 Subject: Note on relation of number of users and OVSF code length --- chapter07/content_ch07.tex | 14 ++++++++++++-- main/chapter07.tex | 4 ++-- 2 files changed, 14 insertions(+), 4 deletions(-) diff --git a/chapter07/content_ch07.tex b/chapter07/content_ch07.tex index 56871e7..82a4b01 100644 --- a/chapter07/content_ch07.tex +++ b/chapter07/content_ch07.tex @@ -1899,8 +1899,18 @@ The rules for creating the \acs{OVSF} code tree are (derived from the constructi The different code lengths have benefits and drawbacks. \begin{itemize} - \item Longer codes have lower data rates. But they have a higher processing gain and better noise immunity. Data decoding works in noisy environments with low \ac{SNR}. - \item Short codes give a higher data rate. However, the processing gain is less as well as the noise immunity. Data decoding may not work in noisy environments. A proper \ac{SNR} is required. + \item Long codes + \begin{itemize} + \item Long codes have lower data rates. + \item But they have a higher processing gain and better noise immunity. Data decoding works in noisy environments with low \ac{SNR}. + \item Furthermore, more users can use the transmission channel, because more orthogonal codes are available (see Figure \ref{fig:ch07:ovsf_code_tree}). + \end{itemize} + \item Short codes + \begin{itemize} + \item Short codes give a higher data rate. + \item However, the processing gain is less as well as the noise immunity. Data decoding may not work in noisy environments. A proper \ac{SNR} is required. + \item Less users can use the transmission channel, because less orthogonal codes are available (see Figure \ref{fig:ch07:ovsf_code_tree}). + \end{itemize} \end{itemize} \subsection{Asynchronous \acs{DS-CDMA}} diff --git a/main/chapter07.tex b/main/chapter07.tex index bfe7099..649e313 100644 --- a/main/chapter07.tex +++ b/main/chapter07.tex @@ -13,8 +13,8 @@ % Configuration \def\thekindofdocument{Lecture Notes} \def\thesubtitle{Chapter 7: Spread Spectrum and Multiple Access} -\def\therevision{1} -\def\therevisiondate{2020-06-06} +\def\therevision{2} +\def\therevisiondate{2020-06-30} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % Header -- cgit v1.1