Uplink interference protection and scheduling for energy efficient OFDMA networks

Abstract

One of the key challenges for future orthogonal frequency division multiple access-based networks is inter-cell interference coordination. With full frequency reuse and small inter-site distances, coping with co-channel interference (CCI) in such networks has become increasingly important. In this article, an uplink interference protection (ULIP) technique to combat CCI is introduced and investigated. The level of uplink interference originating from neighbouring cells (affecting co-channel mobile stations (MSs) in the cell of interest) can be effectively controlled by reducing the transmit power of the interfering MSs. This is done based on the target signal-to-noise-plus-interference ratio (SINR) and tolerable interference of the vulnerable link. Bands are prioritised in order to differentiate those (vulnerable/victim) MSs that are to be protected from interference and those (aggressor/interfering MSs) that are required to sacrifice transmission power to facilitate the protection. Furthermore, MSs are scheduled such that those users with poorer transmission conditions receive the highest interference protection, thus balancing the areal SINR distribution and creating a fairer allocation of the available resources. In addition to interference protection, the individual power reductions also serve to decrease the total system uplink power, resulting in a greener system. It is shown through analytic derivation that the introduction of ULIP guarantees an increase in energy efficiency for all MSs, with the added benefit that gains in overall system throughput are also achievable. Extensive system level simulations validate these findings.

Macrocells-User Protected Interference-Aware Transmit Power Control for LTE-A Heterogeneous Networks

“…During the recent years, many of researchers including 3GPP paid full attention to the interference that HetNets have brought as a by-product together with capacity enhancement [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. To combat the harmful interference in HetNets, different approaches have been studied in the literature.…”

“…Scheduling nonneighboring UEs in same time slots results in reduced interference from neighboring UEs and an acceptable outage ratio; however, this performance is achieved at the cost of reduced throughput, increased complexity, and extra signaling overhead. Besides, there are a few articles in the literature that have discussed power control to handle interference concerns [14][15][16][17][18][19][20][21][22]. The intercell interference coordination (ICIC), enhanced ICIC, and further enhanced ICIC proposed by the 3GPP focused on power control techniques to combat intertier interference [14,15].…”

A distributed virtual MIMO coalition formation framework for energy efficient wireless networks

“…where n RB k is the number of resource blocks assigned to the kth coalition, k sc is the number of subcarriers per resource block, s is the symbol rate per subcarrier, and ε(η k ) is the spectral efficiency for an LTE system [27]. Moreover, η k in Equation 25 must be replaced by Equation 11 when the user transmits in MIMO or by Equation 13 when the user transmits in SIMO mode.…”

“…Furthermore, path loss and shadowing are considered to attenuate the transmitted signal, thus, the received power P r at the BS side is given by [27]:…”

“…The achievable throughput on the link between the kth coalition and the BS when diversity is enhanced is calculated as [27]:…”