Syllabus academic year 2008/2009
(Created 2008-07-17.)

Higher education credits: 7,5. Grading scale: TH. Level: A (Second level). Language of instruction: The course might be given in English. Optional for: C4, C4ks, D4, D4ks, E4, E4ks, MWIR2. Course coordinator: Göran Lindell,, Inst för elektro- och informationsteknik. Recommended prerequisits: ETT051 Digital Communications. Assessment: Written examination (5 h) normally consists of five problems. Approved project is a requirement to be allowed to enter the examination. Home page:

Spread spectrum techniques means that a much larger bandwidth is used for communication than what normally is required with conventional digital communication methods. With this technique high-performing schemes can be obtained, and it is very interesting in special applications. This course considers multi-user digital communication systems based on spread spectrum techniques. The aim of this course is to give very good knowledge concerning principles, concepts, functioning, performance and limitations for such communication systems.

Knowledge and understanding
For a passing grade the student must

Skills and abilities
For a passing grade the student must

Judgement and approach
For a passing grade the student must

Introduction: Several applications are illustrated where spread spectrum techniques give significant performance gains. Limitations with conventional methods are described, as well as basic cell-planning concepts.

Spread spectrum methods: The parameter "processing gain" (alternatively spreading factor) is introduced as a measure of spectrum spreading. Principles for spread spectrum are presented. Several methods are introduced and compared, such as, direct sequence CDMA technique (e.g., 3G, GPS), frequency hopping technique (e.g., Bluetooth), and methods that use very short high-frequency puls shapes (e.g., Ultra-Wide-Band systems, Impulse Radio). Generation of PN-sequences (pseudo-noise), and maximal-length PN-sequences are described.

Multi-user communication based on CDMA technique: Multi-user communication based on CDMA techniqe is explained, including the definition and properties of Hadamard-sequences. The consequences of multi-path propagation in the down-link (to the mobile), as well as in the up-link (to the base-station) are investigated. Communication conditions in the down-link and up-link are described. The properties of the RAKE receiver are presented, and multi-user detection is briefly discussed. Disturbances from other users (multi-user interference), as a consequence of loss of orthogonality, is explained. The selection of codes to users with different bit rates (Orthogonal Variable Spreading Factor Codes) is described. Multi-user communication based on CDMA in combination with OFDM is presented. How to adaptively choose coding-, modulation-, and spreading-parameters depending on the requirements of the users and on the quality of the communication link, is discussed and illustrated.

Some of the applications below are considered in the course: Mobile digital telephony (GSM, EDGE, 3G, 4G), WLAN, GPS, Bluetooth, UWB-systems (impulse radio).

Lecture notes and articles.