Research On Key Technologies Of Utra Fdd HSPA+System

With the commercial extension of HSPA, HSPA system needs a further improvement to achieve a comparable level of performance with LTE-A in order to realize a smooth transition from3G to4Q which makes HSPA+a research hotspot. HSPA+adopts some enhanced technology like MIMO, higher order modulation, advanced receiver and multi-carrier to increase data rate, shorten transmission delay and improve system capacity. Furthermore, HSPA+can better support VoIP (Voice over Internet Protocol).In practical deployment, tens of thousands of cells still work on a single band instead of deploying multiple carrier frequencies owing to the constraints of spectrum resources, so these cell cannot benefit from using current multiple antenna technology. HSDPA multi-flow technology, which allowing different cells to serve the same target UE (User Equipment), was proposed to improve the performance of multi-carrier reception UE in these single frequency cells and to enhance the cell edge coverage. Obiviously HSDPA multi-flow has a significant improvement for the performance of the edge UEs. In this paper, HSDPA multi-flow technology was discussed in details, and also was verified its significant impact for current UEs, especially for the edge UEs, through a system-level simulation.Although HSDPA+plays a significant role on the performance improvement for the edge coverage, UEs who are in the room or in the hotspot places where densily populated still experience poor services. Thus, co-channel heterogeneous network (HetNet) where the conventional macro cells are underlaid with some co-channel low power node (LPN) cells has been recently introduced into HSPA+to satisfy the rapidly growing demands for improving system coverage and capacity. However, the severe cross-tier uplink interference caused by applying the heterogeneous deployment will inevitably limit the uplink performance in HSPA+. Thus, the uplink interference issues have become a critical topic in this area. In this paper, we propose a quasi-distributed uplink interference coordination (QDUIC) scheme based on non-cooperative game with local restriction to reduce the uplink interference in HSPA+HetNet. The existence and uniqueness of Nash equilibrium for our proposed game are justified in detail. Furthermore, to achieve our scheme in practice, we develop a feasible implementation for practical HSPA+HetNet system. System-level simulation results show that our scheme can not only mitigate the uplink interference level, but also save the uplink power consumption and enhance the throughput performance of HSPA+HetNet.