On the joint usage of MIMO and Multiflow in evolved HSPA networks

Even though some mobile network operators are already ramping up Long Term Evolution (LTE) networks, the biggest portion of mobile network revenues will still be generated in HSPA networks for the coming years. Also, the current exponential increase in mobile data rate demand provides a strong motivation to further evolve HSPA networks in parallel to ramping up LTE. While dual-stream MIMO was already introduced in HSPA Rel. 7, Multiflow is currently debated as a promising technology for Rel. 11, allowing two adjacent base stations to have simultaneous data transmissions to the same terminal. In this paper, we go one step further and investigate how MIMO and Multiflow can be used in conjunction. We will see that the two technologies provide complementary gains or even facilitate each other, and should hence be activated jointly. For best performance, it seems highly beneficial to introduce a flexible adjusting of handover margins and smart switching between the technologies depending on terminal SINR, cell load and delay spread.