We present a scheme for reducing the part of the downlink signaling  traffic in wireless multiple access systems that contains scheduling  information.  The theoretical basis of the scheme is that the  scheduling decisions made by the base station are correlated with  the CSI reports from the mobiles.  This correlation can be exploited  by the source coding scheme that is used to compress the scheduling  maps before they are sent to the mobiles. In the proposed scheme,  this idea is implemented by letting the mobiles make tentative  scheduling decisions themselves, and then letting the base station  transmit "agreement maps" instead of raw scheduling maps to the  mobiles.  The agreement maps have lower entropy and they require  less resources to be transmitted than the original scheduling maps  do. The improvement can be substantial.  We also model the task of  finding the optimal scheduling assignments according to the proposed  scheme as a combinatorial optimization problem and present an  efficient algorithm to find the optimal solution.

This paper considers transmission of scheduling information in  OFDMA-based cellular communication systems such as 3GPP long-term  evolution (LTE). These systems provide efficient usage of radio  resources by allowing users to be scheduled dynamically in both  frequency and time. This requires considerable amounts of scheduling  information to be sent to the users.  The paper compares two basic transmission strategies: transmitting a  separate scheduling message to each user versus broadcasting a joint  scheduling message to all users. Different scheduling granularities  are considered, as well as different scheduling algorithms. The  schemes are evaluated in the context of the LTE downlink using  multiuser system simulations, assuming a full-buffer situation.  The results show that separate transmission of the scheduling  information requires a slightly lower overhead than joint  broadcasting, when proportional fair scheduling is employed and the  users are spread out over the cell area. The results also indicate  that the scheduling granularity standardized for LTE provides a good  trade-off between scheduling granularity and overhead.

Blind decoding of control information is used in some wireless  multiple access systems such as LTE to achieve adaptive modulation  and coding, as well as to address the multiple access problem on the  control channel. Blind decoding incurs high computational complexity in mobile terminals. In this paper, we describe a scheme to reduce  the computational complexity associated with the blind decoding. The  main idea is to broadcast a "please-decode-blindly" message to all  terminals that are eligible for scheduling, to instruct a subset of  the terminals to perform the blind search. We propose two schemes to  implement our idea and we investigate their performances via system  simulations.

We present a fast mechanism for determining which channel code that was used on a communication link. In the proposed scheme, the receiver does not need to receive the entire data to determine the actual code. Moreover, the proposed scheme can also be used to determine the interleaving/scrambling sequence that was used at the transmitter. We investigate the performance of the scheme for some standard convolutional codes.

From its first appearance, wireless communications has changed thelife for many people worldwide. Currently, more than half of the world's population are using wireless devices for various purposes on a daily basis. While the early wireless systems could provide simple and specific low-rate services, today's systems can support a variety of more advanced services some of which require high data rate communications. This includes for example web-browsing and streaming multimedia applications. To meet the high demands on the current systems, many technical solutions have been proposed. Many of these solutions are powerful in the sense of boosting the system performance, but on the other hand, they impose a substantial control signaling overhead on the system. The control signaling refers to sending the control information that is necessary to establish and/or maintain the connection as opposed to the payload data that is transmitted during the connection.

In this thesis, we are interested in evaluating the relations between the gain of deploying new techniques and the amount of control signaling overhead they incur. Moreover we are interested in finding efficient algorithms that can potentially reduce the control signaling overhead. More specifically, we first focus on the part of the control signaling overhead that concerns sending the scheduling assignments that describe how the channel resources are allocated among the users. We compare two ways for the signaling of scheduling assignments and we will study how different parameters such as scheduling granularity impact the control signaling overhead. We also provide two schemes that reduce the control signaling overhead substantially. We then provide an algorithm for fast blind identification of channel codes. This algorithm is very useful in improving the so-called blind decoding performance. This is essential since blind decoding is used to achieve adaptive modulation and coding in the control channel of some of the wireless communication systems such as 3GPP Long Term Evolution.