Interference Avoidance In MC-DS-CDMA

Recent trends in wireless communication have led to the shift in attention towards multicarrier modulation. In this thesis, the multicarrier communication used is hybrid MC-DS-CDMA in which the information data is spread in both time and frequency domain. These types of spreading code are termed as two dimensional orthogonal variable spreading factor (2D-OVSF) codes. This hybrid CDMA is having the advantages of both MC-CDMA and MC-DS-CDMA. In this thesis, we are going to characterize another metric-MAI Coefficient which will anticipate the effect of MAI with the time and frequency domain spreading in a particular channel. With the assistance of this MAI coefficient, a novel interference avoidance code assignment strategy is proposed. By mutually considering the acquired MAI impact and the blocking probability in the code tree structure, the proposed strategy can successfully decreasing the MAI for the multi-rate MC-DSCDMA framework, while keeping up great call blocking rate execution

Implementation of a High-Performance Assignment Scheme for Orthogonal Variable-Spreading-Factor Codes in WCDMA Networks

[[abstract]]In WCDMA, channelization is achieved by assigning OVSF codes to different users. The codes in a Node-B are valuable and limited. Much research has been devoted to devising OVSF code-assignment strategies to support as many users as possible. A number of the strategies suffer from a “code-set fragmentation” problem, which increases the call blocking probability (CBP) on the Node-B. In order to resolve this issue some strategies have applied code-exchange and reassignment policies but increased the corresponding complexity. This paper proposes a Best-fit Least Recently Used (BLRU) code-assignment scheme without reassignment to approach an optimal method. Furthermore, we devise a revised version, Queue-assist BLRU (QBLRU), to improve system utilization and to obtain an even lower CBP than the optimal method does. Consequently, code-assignment simulation results present a QBLRU scheme that has a low CBP and the highest utilization, which is a high performance OVSF code-assignment scheme which should be useful for WCDMA networks

Laajakaistaisen CDMA solukkoverkon kapasiteetti makrosoluympäristössä

Tämän diplomityön tarkoitus on tutkia kuormitetun laajakaistaiseen koodijakomenetelmään perustuvan makrosoluverkon kapasiteettia. Työn tavoitteena on selvittää simulointien avulla, miten solukkoverkon palvelemien matkaviestinten käyttäjien eri tiedonsiirtonopeudet ja liikkumisnopeudet vaikuttavat järjestelmän kokonaiskapasiteettiin. Tehonsäädön ja samalla taajuudella olevien solujen välisen kanavananvaihdon toiminnallisuuksien ja parametrien vaikutuksia tutkitaan verkon kapasiteetin kannalta Tutkimus alkaa hajaspektriteknologian perusteiden ja UMTS:n (Universal Mobile Telecommunications System) FDD (Frequency Division Duplex) osan esittelyillä. Laajakaistaisen koodijakoon perustuvan verkon kapasiteetin ominaisuudet esitellään. Makrosoluympäristö määritellään ja sen perusominaisuudet esitellään. Laajakaistaista koodijakoon perustuvaa UMTS-järjestelmää mallintava simulointiohjelmisto kuvaillaan ennen tämän diplomityön simulointien ja tulosten esittelyä ja analysointia. Tämän tutkimuksen simuloinnit suoritetaan yksinkertaisessa esikaupunkityyppisessä makrosoluympäristössä. Laajakaistaisen koodijakoon perustuvan järjestelmän kapasiteetti käyttäytyy hyvin dynaamisesti. Kapasiteetti riippuu käyttäjien jakaumasta verkossa, tiedonsiirtonopeuksista, liikkumisnopeudesta, häiriön määrästä ja tehonsäädön ja samalla taajuudella olevien solujen kanavanvaihdon parametrien valinnasta. Puhekäyttäjien lisäys vaikuttaa enemmän suuria tiedonsiirtonopeuksia kuin alhaisia tiedonsiirtonopeuksia käyttävien tilaajien palvelun laatuun. Solujen väliset häiriöt vaikuttavat merkittävästi verkon kapasiteettiin. Alhaiset tehonsäädön virheet eivät vaikuta merkittävästi hitaasti liikkuvien käyttäjien saamaan palvelun laatuun. Samalla taajuudella olevien solujen kanavanvaihdon kynnysarvo tulisi optimoida, jotta voitaisiin saavuttaa verkon suurin mahdollinen kapasiteetti ja minimoida häiriöt

Multicodes for improved range resolution in radar

Third generation (3G) wireless systems are required to support a variety of communication services like voice, image, motion picture transmission, etc, each of which requires different transmission rates. Multi-code modulation has been introduced therefore as a means of supporting multi-rate services and operating in multi-cell environments [8, 9, 10]. This multi-rate multi-function capability may be used in Radar related applications, too. For example, a single transmitted waveform consisting of two orthogonal codes can be used to simultaneously track a target and obtain high range resolution. Tracking requires low bandwidth and high resolution needs a high bandwidth signal. Orthogonal codes like Walsh codes can be used to provide multiple rates if the codes are chosen from the same matrix, because certain Walsh codes of the same length have very different bandwidths. Therefore, as an extension to its use in communication, multi-codes can be used to enable multi-function operations in a Radar system. The first criterion for choosing a Radar waveform, whether single or multi-code, is its resolving capability in range and Doppler. A measure of range resolution or sensitivity to delay commonly used in Radar literature is the Peak to Sidelobe Level Ratio (PSLR) of the code\u27s autocorrelation function. The multi-codes proposed in this work are found to have better (lower) PSLRs than existing radar codes when the number of simultaneously transmitted codes is large. In the special case of using an entire set of orthogonal codes of any length, the resulting multi-code consists of just a single pulse of thickness equal to the chip width of the code used. This pulse will have a \u27perfect\u27 autocorrelation function with only a single peak at the main lobe and zero sidelobes. This gives the ideal PSLR for radar purposes. An important aspect of using multi-codes in Radar is the need for multiple transmitters to avoid the high peak factor that would result if only a single antenna 15 used. This requires the Radar system to have multiple transmitters as in phased array radar. The best example is a multi-function digital array radar that transmits a unique orthogonal code from each of its antenna elements as described by Rabideau and Parker in [13]. The system described in this publication makes use of the array mode of operation of the Radar to transmit orthogonal codes from each antenna element which are then phased and combined at the receiver. The phase (or angle) of the signal at each receive antenna element can be used to better resolve targets that are spatially separated. This thesis introduces the concept of multicodes in Radar. Further, the advantages of using multiple coded waveforms over the known Radar polyphase codes are demonstrated by simulations

Final report on the evaluation of RRM/CRRM algorithms

Deliverable public del projecte EVERESTThis deliverable provides a definition and a complete evaluation of the RRM/CRRM algorithms selected in D11 and D15, and evolved and refined on an iterative process. The evaluation will be carried out by means of simulations using the simulators provided at D07, and D14.Preprin