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Future-generation radio access networks (RAN) are projected to fulfill the diverse requirements of user equipment (UE) by adopting a heterogeneous network (HetNet) environment. Necessary integration of different radio access technologies (RAT), such as 2G, 3G, 4G, wireless local area network (WLAN), and visible light communication (VLC) is inevitable. Moreover, UEs equipped with diverse requirements will be capable of accessing some or all the RATs. The complex HetNet environment with diverse requirements of UEs will present many challenges. The HetNet is likely to suffer severely from load imbalance among the base stations (BSs) from inheriting the traditional user association scheme such as max-SINR (signal-to-interference-plus-noise ratio)/max-RSSI (received signal strength indicator), unless some sophisticated schemes are invented. In this paper, a novel scheme is devised for a joint-user association for load balancing, where BSs are densely deployed and UEs typically have a certain degree of mobility. Unlike most of the present works, a dynamic network is considered where the position and channel condition of the UEs are not fixed. We develop two complex and distributed association schemes based on probability and d-choices, while carefully considering both loads of the BSs and SINR experienced by the UEs. Numerical results validate the efficiency of the proposed schemes by showing a received data-rate fairness among UEs and an improvement in the UE’s minimum received data rate.

Wireless communication plays an important role in today's environment. To have an effective communication there must be interaction between different layers of OSI model. In this paper we propose a cross layer design for combining queuing and Adaptive Modulation and Coding(AMC) which includes a new modulation technique Gaussian Minimum Shift keying (GMSK). Gaussian Minimum Shift Keying (GMSK) modulation is widely used in cellular and PCS applications. One of the important considerations in the use of modulation is the average power spectral density and especially the spectral density characteristics on the tails. Already proposed AMC module for Cross-layer design has included the modulations like BPSK, QPSK, QAM etc. In order to maximize spectral efficiency under prescribed delay and performance constraints, GMSK is proposed in this paper. I. INTRODUCTIONTo enhance the spectral efficiency while adhering to a target error performance over wireless channels, adaptive modulation and coding (AMC) have been widely used to match transmission mode to time-varying channel state information. Nevertheless queuing systems are practically very important because of the typical trade-off between the various costs of providing service and the costs associated with waiting for the service (or leaving the system without being served). High quality fast service is expensive and long queues may cost a lot including time delay. So a typical problem is to find an optimum system configuration. The solution may be found by applying queuing theory.FIFO (First In First Out) is a very common queuing technique. For FIFO, the first packet in the queue is the first one to be processed, and the buffer size in the router is finite. When the buffer is full there is a possibility for congestion and packets can be dropped and a delay can occur. The effect of buffer overflow also needs to be taken into account while analyzing the overall system performance.The combination of queuing with AMC creates some interesting problems. For instance consider the packet loss rate of a system, which is defined as the ratio of the number of packets received incorrectly at the destination over those transmitted from the source. The packet loss rate is affected by both the queuing overflow, and the packet reception rate. In practical communication systems with randomly arriving packets, the queues may be empty from time to time, leads to a dynamic behavior of the queue.